1 | # engine/base.py |
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2 | # Copyright (C) 2005, 2006, 2007, 2008, 2009 Michael Bayer mike_mp@zzzcomputing.com |
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3 | # |
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4 | # This module is part of SQLAlchemy and is released under |
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5 | # the MIT License: http://www.opensource.org/licenses/mit-license.php |
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6 | |
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7 | |
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8 | """Basic components for SQL execution and interfacing with DB-API. |
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9 | |
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10 | Defines the basic components used to interface DB-API modules with |
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11 | higher-level statement-construction, connection-management, execution |
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12 | and result contexts. |
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13 | |
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14 | """ |
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15 | |
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16 | __all__ = ['BufferedColumnResultProxy', 'BufferedColumnRow', 'BufferedRowResultProxy', 'Compiled', 'Connectable', |
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17 | 'Connection', 'DefaultRunner', 'Dialect', 'Engine', 'ExecutionContext', 'NestedTransaction', 'ResultProxy', |
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18 | 'RootTransaction', 'RowProxy', 'SchemaIterator', 'StringIO', 'Transaction', 'TwoPhaseTransaction', 'connection_memoize'] |
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19 | |
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20 | import inspect, StringIO |
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21 | from sqlalchemy import exc, schema, util, types, log |
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22 | from sqlalchemy.sql import expression |
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23 | |
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24 | class Dialect(object): |
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25 | """Define the behavior of a specific database and DB-API combination. |
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26 | |
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27 | Any aspect of metadata definition, SQL query generation, |
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28 | execution, result-set handling, or anything else which varies |
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29 | between databases is defined under the general category of the |
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30 | Dialect. The Dialect acts as a factory for other |
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31 | database-specific object implementations including |
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32 | ExecutionContext, Compiled, DefaultGenerator, and TypeEngine. |
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33 | |
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34 | All Dialects implement the following attributes: |
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35 | |
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36 | name |
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37 | identifying name for the dialect (i.e. 'sqlite') |
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38 | |
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39 | positional |
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40 | True if the paramstyle for this Dialect is positional. |
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41 | |
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42 | paramstyle |
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43 | the paramstyle to be used (some DB-APIs support multiple |
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44 | paramstyles). |
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45 | |
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46 | convert_unicode |
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47 | True if Unicode conversion should be applied to all ``str`` |
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48 | types. |
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49 | |
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50 | encoding |
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51 | type of encoding to use for unicode, usually defaults to |
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52 | 'utf-8'. |
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53 | |
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54 | schemagenerator |
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55 | a :class:`~sqlalchemy.schema.SchemaVisitor` class which generates |
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56 | schemas. |
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57 | |
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58 | schemadropper |
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59 | a :class:`~sqlalchemy.schema.SchemaVisitor` class which drops schemas. |
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60 | |
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61 | defaultrunner |
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62 | a :class:`~sqlalchemy.schema.SchemaVisitor` class which executes |
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63 | defaults. |
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64 | |
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65 | statement_compiler |
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66 | a :class:`~sqlalchemy.engine.base.Compiled` class used to compile SQL |
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67 | statements |
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68 | |
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69 | preparer |
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70 | a :class:`~sqlalchemy.sql.compiler.IdentifierPreparer` class used to |
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71 | quote identifiers. |
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72 | |
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73 | supports_alter |
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74 | ``True`` if the database supports ``ALTER TABLE``. |
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75 | |
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76 | max_identifier_length |
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77 | The maximum length of identifier names. |
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78 | |
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79 | supports_unicode_statements |
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80 | Indicate whether the DB-API can receive SQL statements as Python unicode strings |
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81 | |
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82 | supports_sane_rowcount |
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83 | Indicate whether the dialect properly implements rowcount for ``UPDATE`` and ``DELETE`` statements. |
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84 | |
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85 | supports_sane_multi_rowcount |
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86 | Indicate whether the dialect properly implements rowcount for ``UPDATE`` and ``DELETE`` statements |
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87 | when executed via executemany. |
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88 | |
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89 | preexecute_pk_sequences |
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90 | Indicate if the dialect should pre-execute sequences on primary key |
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91 | columns during an INSERT, if it's desired that the new row's primary key |
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92 | be available after execution. |
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93 | |
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94 | supports_pk_autoincrement |
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95 | Indicates if the dialect should allow the database to passively assign |
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96 | a primary key column value. |
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97 | |
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98 | dbapi_type_map |
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99 | A mapping of DB-API type objects present in this Dialect's |
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100 | DB-API implmentation mapped to TypeEngine implementations used |
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101 | by the dialect. |
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102 | |
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103 | This is used to apply types to result sets based on the DB-API |
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104 | types present in cursor.description; it only takes effect for |
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105 | result sets against textual statements where no explicit |
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106 | typemap was present. |
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107 | |
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108 | supports_default_values |
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109 | Indicates if the construct ``INSERT INTO tablename DEFAULT VALUES`` is supported |
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110 | |
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111 | description_encoding |
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112 | type of encoding to use for unicode when working with metadata |
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113 | descriptions. If set to ``None`` no encoding will be done. |
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114 | This usually defaults to 'utf-8'. |
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115 | """ |
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116 | |
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117 | def create_connect_args(self, url): |
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118 | """Build DB-API compatible connection arguments. |
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119 | |
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120 | Given a :class:`~sqlalchemy.engine.url.URL` object, returns a tuple |
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121 | consisting of a `*args`/`**kwargs` suitable to send directly |
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122 | to the dbapi's connect function. |
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123 | """ |
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124 | |
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125 | raise NotImplementedError() |
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126 | |
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127 | |
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128 | def type_descriptor(self, typeobj): |
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129 | """Transform a generic type to a database-specific type. |
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130 | |
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131 | Transforms the given :class:`~sqlalchemy.types.TypeEngine` instance |
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132 | from generic to database-specific. |
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133 | |
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134 | Subclasses will usually use the |
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135 | :func:`~sqlalchemy.types.adapt_type` method in the types module to |
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136 | make this job easy. |
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137 | """ |
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138 | |
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139 | raise NotImplementedError() |
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140 | |
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141 | |
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142 | def server_version_info(self, connection): |
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143 | """Return a tuple of the database's version number.""" |
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144 | |
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145 | raise NotImplementedError() |
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146 | |
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147 | def reflecttable(self, connection, table, include_columns=None): |
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148 | """Load table description from the database. |
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149 | |
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150 | Given a :class:`~sqlalchemy.engine.Connection` and a |
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151 | :class:`~sqlalchemy.schema.Table` object, reflect its columns and |
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152 | properties from the database. If include_columns (a list or |
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153 | set) is specified, limit the autoload to the given column |
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154 | names. |
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155 | """ |
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156 | |
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157 | raise NotImplementedError() |
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158 | |
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159 | def has_table(self, connection, table_name, schema=None): |
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160 | """Check the existence of a particular table in the database. |
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161 | |
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162 | Given a :class:`~sqlalchemy.engine.Connection` object and a string |
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163 | `table_name`, return True if the given table (possibly within |
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164 | the specified `schema`) exists in the database, False |
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165 | otherwise. |
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166 | """ |
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167 | |
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168 | raise NotImplementedError() |
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169 | |
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170 | def has_sequence(self, connection, sequence_name, schema=None): |
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171 | """Check the existence of a particular sequence in the database. |
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172 | |
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173 | Given a :class:`~sqlalchemy.engine.Connection` object and a string |
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174 | `sequence_name`, return True if the given sequence exists in |
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175 | the database, False otherwise. |
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176 | """ |
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177 | |
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178 | raise NotImplementedError() |
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179 | |
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180 | def get_default_schema_name(self, connection): |
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181 | """Return the string name of the currently selected schema given a :class:`~sqlalchemy.engine.Connection`.""" |
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182 | |
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183 | raise NotImplementedError() |
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184 | |
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185 | def do_begin(self, connection): |
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186 | """Provide an implementation of *connection.begin()*, given a DB-API connection.""" |
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187 | |
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188 | raise NotImplementedError() |
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189 | |
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190 | def do_rollback(self, connection): |
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191 | """Provide an implementation of *connection.rollback()*, given a DB-API connection.""" |
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192 | |
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193 | raise NotImplementedError() |
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194 | |
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195 | def create_xid(self): |
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196 | """Create a two-phase transaction ID. |
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197 | |
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198 | This id will be passed to do_begin_twophase(), |
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199 | do_rollback_twophase(), do_commit_twophase(). Its format is |
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200 | unspecified. |
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201 | """ |
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202 | |
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203 | raise NotImplementedError() |
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204 | |
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205 | def do_commit(self, connection): |
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206 | """Provide an implementation of *connection.commit()*, given a DB-API connection.""" |
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207 | |
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208 | raise NotImplementedError() |
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209 | |
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210 | def do_savepoint(self, connection, name): |
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211 | """Create a savepoint with the given name on a SQLAlchemy connection.""" |
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212 | |
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213 | raise NotImplementedError() |
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214 | |
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215 | def do_rollback_to_savepoint(self, connection, name): |
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216 | """Rollback a SQL Alchemy connection to the named savepoint.""" |
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217 | |
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218 | raise NotImplementedError() |
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219 | |
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220 | def do_release_savepoint(self, connection, name): |
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221 | """Release the named savepoint on a SQL Alchemy connection.""" |
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222 | |
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223 | raise NotImplementedError() |
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224 | |
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225 | def do_begin_twophase(self, connection, xid): |
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226 | """Begin a two phase transaction on the given connection.""" |
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227 | |
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228 | raise NotImplementedError() |
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229 | |
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230 | def do_prepare_twophase(self, connection, xid): |
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231 | """Prepare a two phase transaction on the given connection.""" |
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232 | |
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233 | raise NotImplementedError() |
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234 | |
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235 | def do_rollback_twophase(self, connection, xid, is_prepared=True, recover=False): |
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236 | """Rollback a two phase transaction on the given connection.""" |
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237 | |
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238 | raise NotImplementedError() |
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239 | |
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240 | def do_commit_twophase(self, connection, xid, is_prepared=True, recover=False): |
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241 | """Commit a two phase transaction on the given connection.""" |
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242 | |
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243 | raise NotImplementedError() |
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244 | |
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245 | def do_recover_twophase(self, connection): |
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246 | """Recover list of uncommited prepared two phase transaction identifiers on the given connection.""" |
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247 | |
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248 | raise NotImplementedError() |
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249 | |
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250 | def do_executemany(self, cursor, statement, parameters, context=None): |
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251 | """Provide an implementation of *cursor.executemany(statement, parameters)*.""" |
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252 | |
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253 | raise NotImplementedError() |
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254 | |
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255 | def do_execute(self, cursor, statement, parameters, context=None): |
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256 | """Provide an implementation of *cursor.execute(statement, parameters)*.""" |
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257 | |
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258 | raise NotImplementedError() |
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259 | |
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260 | def is_disconnect(self, e): |
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261 | """Return True if the given DB-API error indicates an invalid connection""" |
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262 | |
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263 | raise NotImplementedError() |
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264 | |
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265 | |
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266 | class ExecutionContext(object): |
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267 | """A messenger object for a Dialect that corresponds to a single execution. |
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268 | |
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269 | ExecutionContext should have these datamembers: |
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270 | |
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271 | connection |
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272 | Connection object which can be freely used by default value |
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273 | generators to execute SQL. This Connection should reference the |
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274 | same underlying connection/transactional resources of |
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275 | root_connection. |
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276 | |
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277 | root_connection |
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278 | Connection object which is the source of this ExecutionContext. This |
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279 | Connection may have close_with_result=True set, in which case it can |
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280 | only be used once. |
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281 | |
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282 | dialect |
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283 | dialect which created this ExecutionContext. |
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284 | |
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285 | cursor |
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286 | DB-API cursor procured from the connection, |
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287 | |
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288 | compiled |
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289 | if passed to constructor, sqlalchemy.engine.base.Compiled object |
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290 | being executed, |
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291 | |
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292 | statement |
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293 | string version of the statement to be executed. Is either |
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294 | passed to the constructor, or must be created from the |
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295 | sql.Compiled object by the time pre_exec() has completed. |
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296 | |
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297 | parameters |
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298 | bind parameters passed to the execute() method. For compiled |
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299 | statements, this is a dictionary or list of dictionaries. For |
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300 | textual statements, it should be in a format suitable for the |
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301 | dialect's paramstyle (i.e. dict or list of dicts for non |
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302 | positional, list or list of lists/tuples for positional). |
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303 | |
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304 | isinsert |
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305 | True if the statement is an INSERT. |
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306 | |
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307 | isupdate |
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308 | True if the statement is an UPDATE. |
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309 | |
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310 | should_autocommit |
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311 | True if the statement is a "committable" statement |
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312 | |
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313 | postfetch_cols |
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314 | a list of Column objects for which a server-side default |
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315 | or inline SQL expression value was fired off. applies to inserts and updates. |
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316 | |
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317 | |
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318 | """ |
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319 | |
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320 | def create_cursor(self): |
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321 | """Return a new cursor generated from this ExecutionContext's connection. |
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322 | |
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323 | Some dialects may wish to change the behavior of |
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324 | connection.cursor(), such as postgres which may return a PG |
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325 | "server side" cursor. |
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326 | """ |
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327 | |
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328 | raise NotImplementedError() |
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329 | |
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330 | def pre_exec(self): |
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331 | """Called before an execution of a compiled statement. |
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332 | |
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333 | If a compiled statement was passed to this ExecutionContext, |
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334 | the `statement` and `parameters` datamembers must be |
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335 | initialized after this statement is complete. |
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336 | """ |
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337 | |
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338 | raise NotImplementedError() |
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339 | |
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340 | def post_exec(self): |
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341 | """Called after the execution of a compiled statement. |
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342 | |
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343 | If a compiled statement was passed to this ExecutionContext, |
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344 | the `last_insert_ids`, `last_inserted_params`, etc. |
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345 | datamembers should be available after this method completes. |
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346 | """ |
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347 | |
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348 | raise NotImplementedError() |
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349 | |
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350 | def result(self): |
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351 | """Return a result object corresponding to this ExecutionContext. |
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352 | |
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353 | Returns a ResultProxy. |
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354 | """ |
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355 | |
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356 | raise NotImplementedError() |
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357 | |
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358 | def handle_dbapi_exception(self, e): |
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359 | """Receive a DBAPI exception which occured upon execute, result fetch, etc.""" |
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360 | |
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361 | raise NotImplementedError() |
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362 | |
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363 | def should_autocommit_text(self, statement): |
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364 | """Parse the given textual statement and return True if it refers to a "committable" statement""" |
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365 | |
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366 | raise NotImplementedError() |
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367 | |
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368 | def last_inserted_ids(self): |
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369 | """Return the list of the primary key values for the last insert statement executed. |
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370 | |
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371 | This does not apply to straight textual clauses; only to |
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372 | ``sql.Insert`` objects compiled against a ``schema.Table`` |
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373 | object. The order of items in the list is the same as that of |
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374 | the Table's 'primary_key' attribute. |
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375 | """ |
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376 | |
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377 | raise NotImplementedError() |
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378 | |
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379 | def last_inserted_params(self): |
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380 | """Return a dictionary of the full parameter dictionary for the last compiled INSERT statement. |
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381 | |
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382 | Includes any ColumnDefaults or Sequences that were pre-executed. |
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383 | """ |
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384 | |
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385 | raise NotImplementedError() |
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386 | |
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387 | def last_updated_params(self): |
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388 | """Return a dictionary of the full parameter dictionary for the last compiled UPDATE statement. |
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389 | |
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390 | Includes any ColumnDefaults that were pre-executed. |
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391 | """ |
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392 | |
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393 | raise NotImplementedError() |
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394 | |
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395 | def lastrow_has_defaults(self): |
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396 | """Return True if the last INSERT or UPDATE row contained |
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397 | inlined or database-side defaults. |
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398 | """ |
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399 | |
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400 | raise NotImplementedError() |
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401 | |
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402 | |
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403 | class Compiled(object): |
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404 | """Represent a compiled SQL expression. |
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405 | |
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406 | The ``__str__`` method of the ``Compiled`` object should produce |
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407 | the actual text of the statement. ``Compiled`` objects are |
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408 | specific to their underlying database dialect, and also may |
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409 | or may not be specific to the columns referenced within a |
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410 | particular set of bind parameters. In no case should the |
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411 | ``Compiled`` object be dependent on the actual values of those |
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412 | bind parameters, even though it may reference those values as |
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413 | defaults. |
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414 | """ |
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415 | |
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416 | def __init__(self, dialect, statement, column_keys=None, bind=None): |
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417 | """Construct a new ``Compiled`` object. |
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418 | |
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419 | dialect |
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420 | ``Dialect`` to compile against. |
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421 | |
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422 | statement |
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423 | ``ClauseElement`` to be compiled. |
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424 | |
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425 | column_keys |
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426 | a list of column names to be compiled into an INSERT or UPDATE |
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427 | statement. |
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428 | |
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429 | bind |
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430 | Optional Engine or Connection to compile this statement against. |
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431 | |
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432 | """ |
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433 | self.dialect = dialect |
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434 | self.statement = statement |
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435 | self.column_keys = column_keys |
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436 | self.bind = bind |
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437 | self.can_execute = statement.supports_execution |
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438 | |
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439 | def compile(self): |
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440 | """Produce the internal string representation of this element.""" |
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441 | |
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442 | raise NotImplementedError() |
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443 | |
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444 | def __str__(self): |
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445 | """Return the string text of the generated SQL statement.""" |
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446 | |
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447 | raise NotImplementedError() |
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448 | |
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449 | @util.deprecated('Deprecated. Use construct_params(). ' |
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450 | '(supports Unicode key names.)') |
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451 | def get_params(self, **params): |
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452 | return self.construct_params(params) |
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453 | |
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454 | def construct_params(self, params): |
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455 | """Return the bind params for this compiled object. |
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456 | |
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457 | `params` is a dict of string/object pairs whos |
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458 | values will override bind values compiled in |
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459 | to the statement. |
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460 | """ |
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461 | raise NotImplementedError() |
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462 | |
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463 | def execute(self, *multiparams, **params): |
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464 | """Execute this compiled object.""" |
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465 | |
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466 | e = self.bind |
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467 | if e is None: |
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468 | raise exc.UnboundExecutionError("This Compiled object is not bound to any Engine or Connection.") |
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469 | return e._execute_compiled(self, multiparams, params) |
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470 | |
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471 | def scalar(self, *multiparams, **params): |
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472 | """Execute this compiled object and return the result's scalar value.""" |
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473 | |
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474 | return self.execute(*multiparams, **params).scalar() |
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475 | |
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476 | |
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477 | class Connectable(object): |
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478 | """Interface for an object which supports execution of SQL constructs. |
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479 | |
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480 | The two implementations of ``Connectable`` are :class:`Connection` and |
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481 | :class:`Engine`. |
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482 | |
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483 | """ |
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484 | |
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485 | def contextual_connect(self): |
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486 | """Return a Connection object which may be part of an ongoing context.""" |
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487 | |
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488 | raise NotImplementedError() |
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489 | |
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490 | def create(self, entity, **kwargs): |
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491 | """Create a table or index given an appropriate schema object.""" |
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492 | |
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493 | raise NotImplementedError() |
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494 | |
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495 | def drop(self, entity, **kwargs): |
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496 | """Drop a table or index given an appropriate schema object.""" |
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497 | |
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498 | raise NotImplementedError() |
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499 | |
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500 | def execute(self, object, *multiparams, **params): |
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501 | raise NotImplementedError() |
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502 | |
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503 | def _execute_clauseelement(self, elem, multiparams=None, params=None): |
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504 | raise NotImplementedError() |
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505 | |
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506 | class Connection(Connectable): |
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507 | """Provides high-level functionality for a wrapped DB-API connection. |
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508 | |
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509 | Provides execution support for string-based SQL statements as well |
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510 | as ClauseElement, Compiled and DefaultGenerator objects. Provides |
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511 | a begin method to return Transaction objects. |
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512 | |
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513 | The Connection object is **not** thread-safe. |
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514 | |
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515 | .. index:: |
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516 | single: thread safety; Connection |
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517 | |
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518 | """ |
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519 | |
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520 | def __init__(self, engine, connection=None, close_with_result=False, |
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521 | _branch=False): |
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522 | """Construct a new Connection. |
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523 | |
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524 | Connection objects are typically constructed by an |
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525 | :class:`~sqlalchemy.engine.Engine`, see the ``connect()`` and |
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526 | ``contextual_connect()`` methods of Engine. |
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527 | |
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528 | """ |
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529 | |
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530 | self.engine = engine |
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531 | self.__connection = connection or engine.raw_connection() |
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532 | self.__transaction = None |
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533 | self.__close_with_result = close_with_result |
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534 | self.__savepoint_seq = 0 |
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535 | self.__branch = _branch |
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536 | self.__invalid = False |
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537 | |
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538 | def _branch(self): |
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539 | """Return a new Connection which references this Connection's |
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540 | engine and connection; but does not have close_with_result enabled, |
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541 | and also whose close() method does nothing. |
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542 | |
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543 | This is used to execute "sub" statements within a single execution, |
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544 | usually an INSERT statement. |
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545 | |
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546 | """ |
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547 | return self.engine.Connection(self.engine, self.__connection, _branch=True) |
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548 | |
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549 | @property |
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550 | def dialect(self): |
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551 | "Dialect used by this Connection." |
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552 | |
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553 | return self.engine.dialect |
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554 | |
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555 | @property |
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556 | def closed(self): |
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557 | """return True if this connection is closed.""" |
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558 | |
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559 | return not self.__invalid and '_Connection__connection' not in self.__dict__ |
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560 | |
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561 | @property |
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562 | def invalidated(self): |
---|
563 | """return True if this connection was invalidated.""" |
---|
564 | |
---|
565 | return self.__invalid |
---|
566 | |
---|
567 | @property |
---|
568 | def connection(self): |
---|
569 | "The underlying DB-API connection managed by this Connection." |
---|
570 | |
---|
571 | try: |
---|
572 | return self.__connection |
---|
573 | except AttributeError: |
---|
574 | if self.__invalid: |
---|
575 | if self.__transaction is not None: |
---|
576 | raise exc.InvalidRequestError("Can't reconnect until invalid transaction is rolled back") |
---|
577 | self.__connection = self.engine.raw_connection() |
---|
578 | self.__invalid = False |
---|
579 | return self.__connection |
---|
580 | raise exc.InvalidRequestError("This Connection is closed") |
---|
581 | |
---|
582 | @property |
---|
583 | def should_close_with_result(self): |
---|
584 | """Indicates if this Connection should be closed when a corresponding |
---|
585 | ResultProxy is closed; this is essentially an auto-release mode. |
---|
586 | |
---|
587 | """ |
---|
588 | return self.__close_with_result |
---|
589 | |
---|
590 | @property |
---|
591 | def info(self): |
---|
592 | """A collection of per-DB-API connection instance properties.""" |
---|
593 | return self.connection.info |
---|
594 | |
---|
595 | def connect(self): |
---|
596 | """Returns self. |
---|
597 | |
---|
598 | This ``Connectable`` interface method returns self, allowing |
---|
599 | Connections to be used interchangably with Engines in most |
---|
600 | situations that require a bind. |
---|
601 | |
---|
602 | """ |
---|
603 | return self |
---|
604 | |
---|
605 | def contextual_connect(self, **kwargs): |
---|
606 | """Returns self. |
---|
607 | |
---|
608 | This ``Connectable`` interface method returns self, allowing |
---|
609 | Connections to be used interchangably with Engines in most |
---|
610 | situations that require a bind. |
---|
611 | |
---|
612 | """ |
---|
613 | return self |
---|
614 | |
---|
615 | def invalidate(self, exception=None): |
---|
616 | """Invalidate the underlying DBAPI connection associated with this Connection. |
---|
617 | |
---|
618 | The underlying DB-API connection is literally closed (if |
---|
619 | possible), and is discarded. Its source connection pool will |
---|
620 | typically lazily create a new connection to replace it. |
---|
621 | |
---|
622 | Upon the next usage, this Connection will attempt to reconnect |
---|
623 | to the pool with a new connection. |
---|
624 | |
---|
625 | Transactions in progress remain in an "opened" state (even though |
---|
626 | the actual transaction is gone); these must be explicitly |
---|
627 | rolled back before a reconnect on this Connection can proceed. This |
---|
628 | is to prevent applications from accidentally continuing their transactional |
---|
629 | operations in a non-transactional state. |
---|
630 | |
---|
631 | """ |
---|
632 | if self.closed: |
---|
633 | raise exc.InvalidRequestError("This Connection is closed") |
---|
634 | |
---|
635 | if self.__connection.is_valid: |
---|
636 | self.__connection.invalidate(exception) |
---|
637 | del self.__connection |
---|
638 | self.__invalid = True |
---|
639 | |
---|
640 | def detach(self): |
---|
641 | """Detach the underlying DB-API connection from its connection pool. |
---|
642 | |
---|
643 | This Connection instance will remain useable. When closed, |
---|
644 | the DB-API connection will be literally closed and not |
---|
645 | returned to its pool. The pool will typically lazily create a |
---|
646 | new connection to replace the detached connection. |
---|
647 | |
---|
648 | This method can be used to insulate the rest of an application |
---|
649 | from a modified state on a connection (such as a transaction |
---|
650 | isolation level or similar). Also see |
---|
651 | :class:`~sqlalchemy.interfaces.PoolListener` for a mechanism to modify |
---|
652 | connection state when connections leave and return to their |
---|
653 | connection pool. |
---|
654 | |
---|
655 | """ |
---|
656 | self.__connection.detach() |
---|
657 | |
---|
658 | def begin(self): |
---|
659 | """Begin a transaction and return a Transaction handle. |
---|
660 | |
---|
661 | Repeated calls to ``begin`` on the same Connection will create |
---|
662 | a lightweight, emulated nested transaction. Only the |
---|
663 | outermost transaction may ``commit``. Calls to ``commit`` on |
---|
664 | inner transactions are ignored. Any transaction in the |
---|
665 | hierarchy may ``rollback``, however. |
---|
666 | |
---|
667 | """ |
---|
668 | if self.__transaction is None: |
---|
669 | self.__transaction = RootTransaction(self) |
---|
670 | else: |
---|
671 | return Transaction(self, self.__transaction) |
---|
672 | return self.__transaction |
---|
673 | |
---|
674 | def begin_nested(self): |
---|
675 | """Begin a nested transaction and return a Transaction handle. |
---|
676 | |
---|
677 | Nested transactions require SAVEPOINT support in the |
---|
678 | underlying database. Any transaction in the hierarchy may |
---|
679 | ``commit`` and ``rollback``, however the outermost transaction |
---|
680 | still controls the overall ``commit`` or ``rollback`` of the |
---|
681 | transaction of a whole. |
---|
682 | """ |
---|
683 | |
---|
684 | if self.__transaction is None: |
---|
685 | self.__transaction = RootTransaction(self) |
---|
686 | else: |
---|
687 | self.__transaction = NestedTransaction(self, self.__transaction) |
---|
688 | return self.__transaction |
---|
689 | |
---|
690 | def begin_twophase(self, xid=None): |
---|
691 | """Begin a two-phase or XA transaction and return a Transaction handle. |
---|
692 | |
---|
693 | xid |
---|
694 | the two phase transaction id. If not supplied, a random id |
---|
695 | will be generated. |
---|
696 | """ |
---|
697 | |
---|
698 | if self.__transaction is not None: |
---|
699 | raise exc.InvalidRequestError( |
---|
700 | "Cannot start a two phase transaction when a transaction " |
---|
701 | "is already in progress.") |
---|
702 | if xid is None: |
---|
703 | xid = self.engine.dialect.create_xid(); |
---|
704 | self.__transaction = TwoPhaseTransaction(self, xid) |
---|
705 | return self.__transaction |
---|
706 | |
---|
707 | def recover_twophase(self): |
---|
708 | return self.engine.dialect.do_recover_twophase(self) |
---|
709 | |
---|
710 | def rollback_prepared(self, xid, recover=False): |
---|
711 | self.engine.dialect.do_rollback_twophase(self, xid, recover=recover) |
---|
712 | |
---|
713 | def commit_prepared(self, xid, recover=False): |
---|
714 | self.engine.dialect.do_commit_twophase(self, xid, recover=recover) |
---|
715 | |
---|
716 | def in_transaction(self): |
---|
717 | """Return True if a transaction is in progress.""" |
---|
718 | |
---|
719 | return self.__transaction is not None |
---|
720 | |
---|
721 | def _begin_impl(self): |
---|
722 | if self.engine._should_log_info: |
---|
723 | self.engine.logger.info("BEGIN") |
---|
724 | try: |
---|
725 | self.engine.dialect.do_begin(self.connection) |
---|
726 | except Exception, e: |
---|
727 | self._handle_dbapi_exception(e, None, None, None, None) |
---|
728 | raise |
---|
729 | |
---|
730 | def _rollback_impl(self): |
---|
731 | if not self.closed and not self.invalidated and self.__connection.is_valid: |
---|
732 | if self.engine._should_log_info: |
---|
733 | self.engine.logger.info("ROLLBACK") |
---|
734 | try: |
---|
735 | self.engine.dialect.do_rollback(self.connection) |
---|
736 | self.__transaction = None |
---|
737 | except Exception, e: |
---|
738 | self._handle_dbapi_exception(e, None, None, None, None) |
---|
739 | raise |
---|
740 | else: |
---|
741 | self.__transaction = None |
---|
742 | |
---|
743 | def _commit_impl(self): |
---|
744 | if self.engine._should_log_info: |
---|
745 | self.engine.logger.info("COMMIT") |
---|
746 | try: |
---|
747 | self.engine.dialect.do_commit(self.connection) |
---|
748 | self.__transaction = None |
---|
749 | except Exception, e: |
---|
750 | self._handle_dbapi_exception(e, None, None, None, None) |
---|
751 | raise |
---|
752 | |
---|
753 | def _savepoint_impl(self, name=None): |
---|
754 | if name is None: |
---|
755 | self.__savepoint_seq += 1 |
---|
756 | name = 'sa_savepoint_%s' % self.__savepoint_seq |
---|
757 | if self.__connection.is_valid: |
---|
758 | self.engine.dialect.do_savepoint(self, name) |
---|
759 | return name |
---|
760 | |
---|
761 | def _rollback_to_savepoint_impl(self, name, context): |
---|
762 | if self.__connection.is_valid: |
---|
763 | self.engine.dialect.do_rollback_to_savepoint(self, name) |
---|
764 | self.__transaction = context |
---|
765 | |
---|
766 | def _release_savepoint_impl(self, name, context): |
---|
767 | if self.__connection.is_valid: |
---|
768 | self.engine.dialect.do_release_savepoint(self, name) |
---|
769 | self.__transaction = context |
---|
770 | |
---|
771 | def _begin_twophase_impl(self, xid): |
---|
772 | if self.__connection.is_valid: |
---|
773 | self.engine.dialect.do_begin_twophase(self, xid) |
---|
774 | |
---|
775 | def _prepare_twophase_impl(self, xid): |
---|
776 | if self.__connection.is_valid: |
---|
777 | assert isinstance(self.__transaction, TwoPhaseTransaction) |
---|
778 | self.engine.dialect.do_prepare_twophase(self, xid) |
---|
779 | |
---|
780 | def _rollback_twophase_impl(self, xid, is_prepared): |
---|
781 | if self.__connection.is_valid: |
---|
782 | assert isinstance(self.__transaction, TwoPhaseTransaction) |
---|
783 | self.engine.dialect.do_rollback_twophase(self, xid, is_prepared) |
---|
784 | self.__transaction = None |
---|
785 | |
---|
786 | def _commit_twophase_impl(self, xid, is_prepared): |
---|
787 | if self.__connection.is_valid: |
---|
788 | assert isinstance(self.__transaction, TwoPhaseTransaction) |
---|
789 | self.engine.dialect.do_commit_twophase(self, xid, is_prepared) |
---|
790 | self.__transaction = None |
---|
791 | |
---|
792 | def _autorollback(self): |
---|
793 | if not self.in_transaction(): |
---|
794 | self._rollback_impl() |
---|
795 | |
---|
796 | def close(self): |
---|
797 | """Close this Connection.""" |
---|
798 | |
---|
799 | try: |
---|
800 | conn = self.__connection |
---|
801 | except AttributeError: |
---|
802 | return |
---|
803 | if not self.__branch: |
---|
804 | conn.close() |
---|
805 | self.__invalid = False |
---|
806 | del self.__connection |
---|
807 | |
---|
808 | def scalar(self, object, *multiparams, **params): |
---|
809 | """Executes and returns the first column of the first row. |
---|
810 | |
---|
811 | The underlying result/cursor is closed after execution. |
---|
812 | """ |
---|
813 | |
---|
814 | return self.execute(object, *multiparams, **params).scalar() |
---|
815 | |
---|
816 | def statement_compiler(self, statement, **kwargs): |
---|
817 | return self.dialect.statement_compiler(self.dialect, statement, bind=self, **kwargs) |
---|
818 | |
---|
819 | def execute(self, object, *multiparams, **params): |
---|
820 | """Executes and returns a ResultProxy.""" |
---|
821 | |
---|
822 | for c in type(object).__mro__: |
---|
823 | if c in Connection.executors: |
---|
824 | return Connection.executors[c](self, object, multiparams, params) |
---|
825 | else: |
---|
826 | raise exc.InvalidRequestError("Unexecutable object type: " + str(type(object))) |
---|
827 | |
---|
828 | def __distill_params(self, multiparams, params): |
---|
829 | """given arguments from the calling form *multiparams, **params, return a list |
---|
830 | of bind parameter structures, usually a list of dictionaries. |
---|
831 | |
---|
832 | in the case of 'raw' execution which accepts positional parameters, |
---|
833 | it may be a list of tuples or lists.""" |
---|
834 | |
---|
835 | if not multiparams: |
---|
836 | if params: |
---|
837 | return [params] |
---|
838 | else: |
---|
839 | return [] |
---|
840 | elif len(multiparams) == 1: |
---|
841 | zero = multiparams[0] |
---|
842 | if isinstance(zero, (list, tuple)): |
---|
843 | if not zero or hasattr(zero[0], '__iter__'): |
---|
844 | return zero |
---|
845 | else: |
---|
846 | return [zero] |
---|
847 | elif hasattr(zero, 'keys'): |
---|
848 | return [zero] |
---|
849 | else: |
---|
850 | return [[zero]] |
---|
851 | else: |
---|
852 | if hasattr(multiparams[0], '__iter__'): |
---|
853 | return multiparams |
---|
854 | else: |
---|
855 | return [multiparams] |
---|
856 | |
---|
857 | def _execute_function(self, func, multiparams, params): |
---|
858 | return self._execute_clauseelement(func.select(), multiparams, params) |
---|
859 | |
---|
860 | def _execute_default(self, default, multiparams, params): |
---|
861 | return self.engine.dialect.defaultrunner(self.__create_execution_context()).traverse_single(default) |
---|
862 | |
---|
863 | def _execute_clauseelement(self, elem, multiparams, params): |
---|
864 | params = self.__distill_params(multiparams, params) |
---|
865 | if params: |
---|
866 | keys = params[0].keys() |
---|
867 | else: |
---|
868 | keys = [] |
---|
869 | |
---|
870 | context = self.__create_execution_context( |
---|
871 | compiled=elem.compile(dialect=self.dialect, column_keys=keys, inline=len(params) > 1), |
---|
872 | parameters=params |
---|
873 | ) |
---|
874 | return self.__execute_context(context) |
---|
875 | |
---|
876 | def _execute_compiled(self, compiled, multiparams, params): |
---|
877 | """Execute a sql.Compiled object.""" |
---|
878 | |
---|
879 | context = self.__create_execution_context( |
---|
880 | compiled=compiled, |
---|
881 | parameters=self.__distill_params(multiparams, params) |
---|
882 | ) |
---|
883 | return self.__execute_context(context) |
---|
884 | |
---|
885 | def _execute_text(self, statement, multiparams, params): |
---|
886 | parameters = self.__distill_params(multiparams, params) |
---|
887 | context = self.__create_execution_context(statement=statement, parameters=parameters) |
---|
888 | return self.__execute_context(context) |
---|
889 | |
---|
890 | def __execute_context(self, context): |
---|
891 | if context.compiled: |
---|
892 | context.pre_exec() |
---|
893 | if context.executemany: |
---|
894 | self._cursor_executemany(context.cursor, context.statement, context.parameters, context=context) |
---|
895 | else: |
---|
896 | self._cursor_execute(context.cursor, context.statement, context.parameters[0], context=context) |
---|
897 | if context.compiled: |
---|
898 | context.post_exec() |
---|
899 | if context.should_autocommit and not self.in_transaction(): |
---|
900 | self._commit_impl() |
---|
901 | return context.get_result_proxy() |
---|
902 | |
---|
903 | def _execute_ddl(self, ddl, params, multiparams): |
---|
904 | if params: |
---|
905 | schema_item, params = params[0], params[1:] |
---|
906 | else: |
---|
907 | schema_item = None |
---|
908 | return ddl(None, schema_item, self, *params, **multiparams) |
---|
909 | |
---|
910 | def _handle_dbapi_exception(self, e, statement, parameters, cursor, context): |
---|
911 | if getattr(self, '_reentrant_error', False): |
---|
912 | raise exc.DBAPIError.instance(None, None, e) |
---|
913 | self._reentrant_error = True |
---|
914 | try: |
---|
915 | if not isinstance(e, self.dialect.dbapi.Error): |
---|
916 | return |
---|
917 | |
---|
918 | if context: |
---|
919 | context.handle_dbapi_exception(e) |
---|
920 | |
---|
921 | is_disconnect = self.dialect.is_disconnect(e) |
---|
922 | if is_disconnect: |
---|
923 | self.invalidate(e) |
---|
924 | self.engine.dispose() |
---|
925 | else: |
---|
926 | if cursor: |
---|
927 | cursor.close() |
---|
928 | self._autorollback() |
---|
929 | if self.__close_with_result: |
---|
930 | self.close() |
---|
931 | raise exc.DBAPIError.instance(statement, parameters, e, connection_invalidated=is_disconnect) |
---|
932 | finally: |
---|
933 | del self._reentrant_error |
---|
934 | |
---|
935 | def __create_execution_context(self, **kwargs): |
---|
936 | try: |
---|
937 | dialect = self.engine.dialect |
---|
938 | return dialect.execution_ctx_cls(dialect, connection=self, **kwargs) |
---|
939 | except Exception, e: |
---|
940 | self._handle_dbapi_exception(e, kwargs.get('statement', None), kwargs.get('parameters', None), None, None) |
---|
941 | raise |
---|
942 | |
---|
943 | def _cursor_execute(self, cursor, statement, parameters, context=None): |
---|
944 | if self.engine._should_log_info: |
---|
945 | self.engine.logger.info(statement) |
---|
946 | self.engine.logger.info(repr(parameters)) |
---|
947 | try: |
---|
948 | self.dialect.do_execute(cursor, statement, parameters, context=context) |
---|
949 | except Exception, e: |
---|
950 | self._handle_dbapi_exception(e, statement, parameters, cursor, context) |
---|
951 | raise |
---|
952 | |
---|
953 | def _cursor_executemany(self, cursor, statement, parameters, context=None): |
---|
954 | if self.engine._should_log_info: |
---|
955 | self.engine.logger.info(statement) |
---|
956 | self.engine.logger.info(repr(parameters)) |
---|
957 | try: |
---|
958 | self.dialect.do_executemany(cursor, statement, parameters, context=context) |
---|
959 | except Exception, e: |
---|
960 | self._handle_dbapi_exception(e, statement, parameters, cursor, context) |
---|
961 | raise |
---|
962 | |
---|
963 | # poor man's multimethod/generic function thingy |
---|
964 | executors = { |
---|
965 | expression.Function: _execute_function, |
---|
966 | expression.ClauseElement: _execute_clauseelement, |
---|
967 | Compiled: _execute_compiled, |
---|
968 | schema.SchemaItem: _execute_default, |
---|
969 | schema.DDL: _execute_ddl, |
---|
970 | basestring: _execute_text |
---|
971 | } |
---|
972 | |
---|
973 | def create(self, entity, **kwargs): |
---|
974 | """Create a Table or Index given an appropriate Schema object.""" |
---|
975 | |
---|
976 | return self.engine.create(entity, connection=self, **kwargs) |
---|
977 | |
---|
978 | def drop(self, entity, **kwargs): |
---|
979 | """Drop a Table or Index given an appropriate Schema object.""" |
---|
980 | |
---|
981 | return self.engine.drop(entity, connection=self, **kwargs) |
---|
982 | |
---|
983 | def reflecttable(self, table, include_columns=None): |
---|
984 | """Reflect the columns in the given string table name from the database.""" |
---|
985 | |
---|
986 | return self.engine.reflecttable(table, self, include_columns) |
---|
987 | |
---|
988 | def default_schema_name(self): |
---|
989 | return self.engine.dialect.get_default_schema_name(self) |
---|
990 | |
---|
991 | def run_callable(self, callable_): |
---|
992 | return callable_(self) |
---|
993 | |
---|
994 | class Transaction(object): |
---|
995 | """Represent a Transaction in progress. |
---|
996 | |
---|
997 | The Transaction object is **not** threadsafe. |
---|
998 | |
---|
999 | .. index:: |
---|
1000 | single: thread safety; Transaction |
---|
1001 | |
---|
1002 | """ |
---|
1003 | |
---|
1004 | def __init__(self, connection, parent): |
---|
1005 | self.connection = connection |
---|
1006 | self._parent = parent or self |
---|
1007 | self.is_active = True |
---|
1008 | |
---|
1009 | def close(self): |
---|
1010 | """Close this transaction. |
---|
1011 | |
---|
1012 | If this transaction is the base transaction in a begin/commit |
---|
1013 | nesting, the transaction will rollback(). Otherwise, the |
---|
1014 | method returns. |
---|
1015 | |
---|
1016 | This is used to cancel a Transaction without affecting the scope of |
---|
1017 | an enclosing transaction. |
---|
1018 | """ |
---|
1019 | if not self._parent.is_active: |
---|
1020 | return |
---|
1021 | if self._parent is self: |
---|
1022 | self.rollback() |
---|
1023 | |
---|
1024 | def rollback(self): |
---|
1025 | if not self._parent.is_active: |
---|
1026 | return |
---|
1027 | self.is_active = False |
---|
1028 | self._do_rollback() |
---|
1029 | |
---|
1030 | def _do_rollback(self): |
---|
1031 | self._parent.rollback() |
---|
1032 | |
---|
1033 | def commit(self): |
---|
1034 | if not self._parent.is_active: |
---|
1035 | raise exc.InvalidRequestError("This transaction is inactive") |
---|
1036 | self._do_commit() |
---|
1037 | self.is_active = False |
---|
1038 | |
---|
1039 | def _do_commit(self): |
---|
1040 | pass |
---|
1041 | |
---|
1042 | def __enter__(self): |
---|
1043 | return self |
---|
1044 | |
---|
1045 | def __exit__(self, type, value, traceback): |
---|
1046 | if type is None and self.is_active: |
---|
1047 | self.commit() |
---|
1048 | else: |
---|
1049 | self.rollback() |
---|
1050 | |
---|
1051 | class RootTransaction(Transaction): |
---|
1052 | def __init__(self, connection): |
---|
1053 | super(RootTransaction, self).__init__(connection, None) |
---|
1054 | self.connection._begin_impl() |
---|
1055 | |
---|
1056 | def _do_rollback(self): |
---|
1057 | self.connection._rollback_impl() |
---|
1058 | |
---|
1059 | def _do_commit(self): |
---|
1060 | self.connection._commit_impl() |
---|
1061 | |
---|
1062 | class NestedTransaction(Transaction): |
---|
1063 | def __init__(self, connection, parent): |
---|
1064 | super(NestedTransaction, self).__init__(connection, parent) |
---|
1065 | self._savepoint = self.connection._savepoint_impl() |
---|
1066 | |
---|
1067 | def _do_rollback(self): |
---|
1068 | self.connection._rollback_to_savepoint_impl(self._savepoint, self._parent) |
---|
1069 | |
---|
1070 | def _do_commit(self): |
---|
1071 | self.connection._release_savepoint_impl(self._savepoint, self._parent) |
---|
1072 | |
---|
1073 | class TwoPhaseTransaction(Transaction): |
---|
1074 | def __init__(self, connection, xid): |
---|
1075 | super(TwoPhaseTransaction, self).__init__(connection, None) |
---|
1076 | self._is_prepared = False |
---|
1077 | self.xid = xid |
---|
1078 | self.connection._begin_twophase_impl(self.xid) |
---|
1079 | |
---|
1080 | def prepare(self): |
---|
1081 | if not self._parent.is_active: |
---|
1082 | raise exc.InvalidRequestError("This transaction is inactive") |
---|
1083 | self.connection._prepare_twophase_impl(self.xid) |
---|
1084 | self._is_prepared = True |
---|
1085 | |
---|
1086 | def _do_rollback(self): |
---|
1087 | self.connection._rollback_twophase_impl(self.xid, self._is_prepared) |
---|
1088 | |
---|
1089 | def _do_commit(self): |
---|
1090 | self.connection._commit_twophase_impl(self.xid, self._is_prepared) |
---|
1091 | |
---|
1092 | class Engine(Connectable): |
---|
1093 | """ |
---|
1094 | Connects a :class:`~sqlalchemy.pool.Pool` and :class:`~sqlalchemy.engine.base.Dialect` |
---|
1095 | together to provide a source of database connectivity and behavior. |
---|
1096 | |
---|
1097 | """ |
---|
1098 | |
---|
1099 | def __init__(self, pool, dialect, url, echo=None, proxy=None): |
---|
1100 | self.pool = pool |
---|
1101 | self.url = url |
---|
1102 | self.dialect = dialect |
---|
1103 | self.echo = echo |
---|
1104 | self.engine = self |
---|
1105 | self.logger = log.instance_logger(self, echoflag=echo) |
---|
1106 | if proxy: |
---|
1107 | self.Connection = _proxy_connection_cls(Connection, proxy) |
---|
1108 | else: |
---|
1109 | self.Connection = Connection |
---|
1110 | |
---|
1111 | @property |
---|
1112 | def name(self): |
---|
1113 | "String name of the :class:`~sqlalchemy.engine.Dialect` in use by this ``Engine``." |
---|
1114 | |
---|
1115 | return self.dialect.name |
---|
1116 | |
---|
1117 | echo = log.echo_property() |
---|
1118 | |
---|
1119 | def __repr__(self): |
---|
1120 | return 'Engine(%s)' % str(self.url) |
---|
1121 | |
---|
1122 | def dispose(self): |
---|
1123 | self.pool.dispose() |
---|
1124 | self.pool = self.pool.recreate() |
---|
1125 | |
---|
1126 | def create(self, entity, connection=None, **kwargs): |
---|
1127 | """Create a table or index within this engine's database connection given a schema.Table object.""" |
---|
1128 | |
---|
1129 | self._run_visitor(self.dialect.schemagenerator, entity, connection=connection, **kwargs) |
---|
1130 | |
---|
1131 | def drop(self, entity, connection=None, **kwargs): |
---|
1132 | """Drop a table or index within this engine's database connection given a schema.Table object.""" |
---|
1133 | |
---|
1134 | self._run_visitor(self.dialect.schemadropper, entity, connection=connection, **kwargs) |
---|
1135 | |
---|
1136 | def _execute_default(self, default): |
---|
1137 | connection = self.contextual_connect() |
---|
1138 | try: |
---|
1139 | return connection._execute_default(default, (), {}) |
---|
1140 | finally: |
---|
1141 | connection.close() |
---|
1142 | |
---|
1143 | @property |
---|
1144 | def func(self): |
---|
1145 | return expression._FunctionGenerator(bind=self) |
---|
1146 | |
---|
1147 | def text(self, text, *args, **kwargs): |
---|
1148 | """Return a sql.text() object for performing literal queries.""" |
---|
1149 | |
---|
1150 | return expression.text(text, bind=self, *args, **kwargs) |
---|
1151 | |
---|
1152 | def _run_visitor(self, visitorcallable, element, connection=None, **kwargs): |
---|
1153 | if connection is None: |
---|
1154 | conn = self.contextual_connect(close_with_result=False) |
---|
1155 | else: |
---|
1156 | conn = connection |
---|
1157 | try: |
---|
1158 | visitorcallable(self.dialect, conn, **kwargs).traverse(element) |
---|
1159 | finally: |
---|
1160 | if connection is None: |
---|
1161 | conn.close() |
---|
1162 | |
---|
1163 | def transaction(self, callable_, connection=None, *args, **kwargs): |
---|
1164 | """Execute the given function within a transaction boundary. |
---|
1165 | |
---|
1166 | This is a shortcut for explicitly calling `begin()` and `commit()` |
---|
1167 | and optionally `rollback()` when exceptions are raised. The |
---|
1168 | given `*args` and `**kwargs` will be passed to the function, as |
---|
1169 | well as the Connection used in the transaction. |
---|
1170 | """ |
---|
1171 | |
---|
1172 | if connection is None: |
---|
1173 | conn = self.contextual_connect() |
---|
1174 | else: |
---|
1175 | conn = connection |
---|
1176 | try: |
---|
1177 | trans = conn.begin() |
---|
1178 | try: |
---|
1179 | ret = callable_(conn, *args, **kwargs) |
---|
1180 | trans.commit() |
---|
1181 | return ret |
---|
1182 | except: |
---|
1183 | trans.rollback() |
---|
1184 | raise |
---|
1185 | finally: |
---|
1186 | if connection is None: |
---|
1187 | conn.close() |
---|
1188 | |
---|
1189 | def run_callable(self, callable_, connection=None, *args, **kwargs): |
---|
1190 | if connection is None: |
---|
1191 | conn = self.contextual_connect() |
---|
1192 | else: |
---|
1193 | conn = connection |
---|
1194 | try: |
---|
1195 | return callable_(conn, *args, **kwargs) |
---|
1196 | finally: |
---|
1197 | if connection is None: |
---|
1198 | conn.close() |
---|
1199 | |
---|
1200 | def execute(self, statement, *multiparams, **params): |
---|
1201 | connection = self.contextual_connect(close_with_result=True) |
---|
1202 | return connection.execute(statement, *multiparams, **params) |
---|
1203 | |
---|
1204 | def scalar(self, statement, *multiparams, **params): |
---|
1205 | return self.execute(statement, *multiparams, **params).scalar() |
---|
1206 | |
---|
1207 | def _execute_clauseelement(self, elem, multiparams=None, params=None): |
---|
1208 | connection = self.contextual_connect(close_with_result=True) |
---|
1209 | return connection._execute_clauseelement(elem, multiparams, params) |
---|
1210 | |
---|
1211 | def _execute_compiled(self, compiled, multiparams, params): |
---|
1212 | connection = self.contextual_connect(close_with_result=True) |
---|
1213 | return connection._execute_compiled(compiled, multiparams, params) |
---|
1214 | |
---|
1215 | def statement_compiler(self, statement, **kwargs): |
---|
1216 | return self.dialect.statement_compiler(self.dialect, statement, bind=self, **kwargs) |
---|
1217 | |
---|
1218 | def connect(self, **kwargs): |
---|
1219 | """Return a newly allocated Connection object.""" |
---|
1220 | |
---|
1221 | return self.Connection(self, **kwargs) |
---|
1222 | |
---|
1223 | def contextual_connect(self, close_with_result=False, **kwargs): |
---|
1224 | """Return a Connection object which may be newly allocated, or may be part of some ongoing context. |
---|
1225 | |
---|
1226 | This Connection is meant to be used by the various "auto-connecting" operations. |
---|
1227 | """ |
---|
1228 | |
---|
1229 | return self.Connection(self, self.pool.connect(), close_with_result=close_with_result, **kwargs) |
---|
1230 | |
---|
1231 | def table_names(self, schema=None, connection=None): |
---|
1232 | """Return a list of all table names available in the database. |
---|
1233 | |
---|
1234 | schema: |
---|
1235 | Optional, retrieve names from a non-default schema. |
---|
1236 | |
---|
1237 | connection: |
---|
1238 | Optional, use a specified connection. Default is the |
---|
1239 | ``contextual_connect`` for this ``Engine``. |
---|
1240 | """ |
---|
1241 | |
---|
1242 | if connection is None: |
---|
1243 | conn = self.contextual_connect() |
---|
1244 | else: |
---|
1245 | conn = connection |
---|
1246 | if not schema: |
---|
1247 | try: |
---|
1248 | schema = self.dialect.get_default_schema_name(conn) |
---|
1249 | except NotImplementedError: |
---|
1250 | pass |
---|
1251 | try: |
---|
1252 | return self.dialect.table_names(conn, schema) |
---|
1253 | finally: |
---|
1254 | if connection is None: |
---|
1255 | conn.close() |
---|
1256 | |
---|
1257 | def reflecttable(self, table, connection=None, include_columns=None): |
---|
1258 | """Given a Table object, reflects its columns and properties from the database.""" |
---|
1259 | |
---|
1260 | if connection is None: |
---|
1261 | conn = self.contextual_connect() |
---|
1262 | else: |
---|
1263 | conn = connection |
---|
1264 | try: |
---|
1265 | self.dialect.reflecttable(conn, table, include_columns) |
---|
1266 | finally: |
---|
1267 | if connection is None: |
---|
1268 | conn.close() |
---|
1269 | |
---|
1270 | def has_table(self, table_name, schema=None): |
---|
1271 | return self.run_callable(lambda c: self.dialect.has_table(c, table_name, schema=schema)) |
---|
1272 | |
---|
1273 | def raw_connection(self): |
---|
1274 | """Return a DB-API connection.""" |
---|
1275 | |
---|
1276 | return self.pool.unique_connection() |
---|
1277 | |
---|
1278 | def _proxy_connection_cls(cls, proxy): |
---|
1279 | class ProxyConnection(cls): |
---|
1280 | def execute(self, object, *multiparams, **params): |
---|
1281 | return proxy.execute(self, super(ProxyConnection, self).execute, object, *multiparams, **params) |
---|
1282 | |
---|
1283 | def _execute_clauseelement(self, elem, multiparams=None, params=None): |
---|
1284 | return proxy.execute(self, super(ProxyConnection, self).execute, elem, *(multiparams or []), **(params or {})) |
---|
1285 | |
---|
1286 | def _cursor_execute(self, cursor, statement, parameters, context=None): |
---|
1287 | return proxy.cursor_execute(super(ProxyConnection, self)._cursor_execute, cursor, statement, parameters, context, False) |
---|
1288 | |
---|
1289 | def _cursor_executemany(self, cursor, statement, parameters, context=None): |
---|
1290 | return proxy.cursor_execute(super(ProxyConnection, self)._cursor_executemany, cursor, statement, parameters, context, True) |
---|
1291 | |
---|
1292 | return ProxyConnection |
---|
1293 | |
---|
1294 | class RowProxy(object): |
---|
1295 | """Proxy a single cursor row for a parent ResultProxy. |
---|
1296 | |
---|
1297 | Mostly follows "ordered dictionary" behavior, mapping result |
---|
1298 | values to the string-based column name, the integer position of |
---|
1299 | the result in the row, as well as Column instances which can be |
---|
1300 | mapped to the original Columns that produced this result set (for |
---|
1301 | results that correspond to constructed SQL expressions). |
---|
1302 | """ |
---|
1303 | |
---|
1304 | __slots__ = ['__parent', '__row'] |
---|
1305 | |
---|
1306 | def __init__(self, parent, row): |
---|
1307 | """RowProxy objects are constructed by ResultProxy objects.""" |
---|
1308 | |
---|
1309 | self.__parent = parent |
---|
1310 | self.__row = row |
---|
1311 | if self.__parent._echo: |
---|
1312 | self.__parent.context.engine.logger.debug("Row " + repr(row)) |
---|
1313 | |
---|
1314 | def close(self): |
---|
1315 | """Close the parent ResultProxy.""" |
---|
1316 | |
---|
1317 | self.__parent.close() |
---|
1318 | |
---|
1319 | def __contains__(self, key): |
---|
1320 | return self.__parent._has_key(self.__row, key) |
---|
1321 | |
---|
1322 | def __len__(self): |
---|
1323 | return len(self.__row) |
---|
1324 | |
---|
1325 | def __iter__(self): |
---|
1326 | for i in xrange(len(self.__row)): |
---|
1327 | yield self.__parent._get_col(self.__row, i) |
---|
1328 | |
---|
1329 | __hash__ = None |
---|
1330 | |
---|
1331 | def __eq__(self, other): |
---|
1332 | return ((other is self) or |
---|
1333 | (other == tuple(self.__parent._get_col(self.__row, key) |
---|
1334 | for key in xrange(len(self.__row))))) |
---|
1335 | |
---|
1336 | def __ne__(self, other): |
---|
1337 | return not self.__eq__(other) |
---|
1338 | |
---|
1339 | def __repr__(self): |
---|
1340 | return repr(tuple(self)) |
---|
1341 | |
---|
1342 | def has_key(self, key): |
---|
1343 | """Return True if this RowProxy contains the given key.""" |
---|
1344 | |
---|
1345 | return self.__parent._has_key(self.__row, key) |
---|
1346 | |
---|
1347 | def __getitem__(self, key): |
---|
1348 | return self.__parent._get_col(self.__row, key) |
---|
1349 | |
---|
1350 | def __getattr__(self, name): |
---|
1351 | try: |
---|
1352 | return self.__parent._get_col(self.__row, name) |
---|
1353 | except KeyError, e: |
---|
1354 | raise AttributeError(e.args[0]) |
---|
1355 | |
---|
1356 | def items(self): |
---|
1357 | """Return a list of tuples, each tuple containing a key/value pair.""" |
---|
1358 | |
---|
1359 | return [(key, getattr(self, key)) for key in self.iterkeys()] |
---|
1360 | |
---|
1361 | def keys(self): |
---|
1362 | """Return the list of keys as strings represented by this RowProxy.""" |
---|
1363 | |
---|
1364 | return self.__parent.keys |
---|
1365 | |
---|
1366 | def iterkeys(self): |
---|
1367 | return iter(self.__parent.keys) |
---|
1368 | |
---|
1369 | def values(self): |
---|
1370 | """Return the values represented by this RowProxy as a list.""" |
---|
1371 | |
---|
1372 | return list(self) |
---|
1373 | |
---|
1374 | def itervalues(self): |
---|
1375 | return iter(self) |
---|
1376 | |
---|
1377 | class BufferedColumnRow(RowProxy): |
---|
1378 | def __init__(self, parent, row): |
---|
1379 | row = [ResultProxy._get_col(parent, row, i) for i in xrange(len(row))] |
---|
1380 | super(BufferedColumnRow, self).__init__(parent, row) |
---|
1381 | |
---|
1382 | |
---|
1383 | class ResultProxy(object): |
---|
1384 | """Wraps a DB-API cursor object to provide easier access to row columns. |
---|
1385 | |
---|
1386 | Individual columns may be accessed by their integer position, |
---|
1387 | case-insensitive column name, or by ``schema.Column`` |
---|
1388 | object. e.g.:: |
---|
1389 | |
---|
1390 | row = fetchone() |
---|
1391 | |
---|
1392 | col1 = row[0] # access via integer position |
---|
1393 | |
---|
1394 | col2 = row['col2'] # access via name |
---|
1395 | |
---|
1396 | col3 = row[mytable.c.mycol] # access via Column object. |
---|
1397 | |
---|
1398 | ResultProxy also contains a map of TypeEngine objects and will |
---|
1399 | invoke the appropriate ``result_processor()`` method before |
---|
1400 | returning columns, as well as the ExecutionContext corresponding |
---|
1401 | to the statement execution. It provides several methods for which |
---|
1402 | to obtain information from the underlying ExecutionContext. |
---|
1403 | """ |
---|
1404 | |
---|
1405 | _process_row = RowProxy |
---|
1406 | |
---|
1407 | def __init__(self, context): |
---|
1408 | """ResultProxy objects are constructed via the execute() method on SQLEngine.""" |
---|
1409 | self.context = context |
---|
1410 | self.dialect = context.dialect |
---|
1411 | self.closed = False |
---|
1412 | self.cursor = context.cursor |
---|
1413 | self.connection = context.root_connection |
---|
1414 | self._echo = context.engine._should_log_info |
---|
1415 | self._init_metadata() |
---|
1416 | |
---|
1417 | @property |
---|
1418 | def rowcount(self): |
---|
1419 | if self._rowcount is None: |
---|
1420 | return self.context.get_rowcount() |
---|
1421 | else: |
---|
1422 | return self._rowcount |
---|
1423 | |
---|
1424 | @property |
---|
1425 | def lastrowid(self): |
---|
1426 | return self.cursor.lastrowid |
---|
1427 | |
---|
1428 | @property |
---|
1429 | def out_parameters(self): |
---|
1430 | return self.context.out_parameters |
---|
1431 | |
---|
1432 | def _init_metadata(self): |
---|
1433 | metadata = self.cursor.description |
---|
1434 | if metadata is None: |
---|
1435 | # no results, get rowcount (which requires open cursor on some DB's such as firebird), |
---|
1436 | # then close |
---|
1437 | self._rowcount = self.context.get_rowcount() |
---|
1438 | self.close() |
---|
1439 | return |
---|
1440 | |
---|
1441 | self._rowcount = None |
---|
1442 | self._props = util.populate_column_dict(None) |
---|
1443 | self._props.creator = self.__key_fallback() |
---|
1444 | self.keys = [] |
---|
1445 | |
---|
1446 | typemap = self.dialect.dbapi_type_map |
---|
1447 | |
---|
1448 | for i, item in enumerate(metadata): |
---|
1449 | colname = item[0] |
---|
1450 | if self.dialect.description_encoding: |
---|
1451 | colname = colname.decode(self.dialect.description_encoding) |
---|
1452 | |
---|
1453 | if '.' in colname: |
---|
1454 | # sqlite will in some circumstances prepend table name to colnames, so strip |
---|
1455 | origname = colname |
---|
1456 | colname = colname.split('.')[-1] |
---|
1457 | else: |
---|
1458 | origname = None |
---|
1459 | |
---|
1460 | if self.context.result_map: |
---|
1461 | try: |
---|
1462 | (name, obj, type_) = self.context.result_map[colname.lower()] |
---|
1463 | except KeyError: |
---|
1464 | (name, obj, type_) = (colname, None, typemap.get(item[1], types.NULLTYPE)) |
---|
1465 | else: |
---|
1466 | (name, obj, type_) = (colname, None, typemap.get(item[1], types.NULLTYPE)) |
---|
1467 | |
---|
1468 | rec = (type_, type_.dialect_impl(self.dialect).result_processor(self.dialect), i) |
---|
1469 | |
---|
1470 | if self._props.setdefault(name.lower(), rec) is not rec: |
---|
1471 | self._props[name.lower()] = (type_, self.__ambiguous_processor(name), 0) |
---|
1472 | |
---|
1473 | # store the "origname" if we truncated (sqlite only) |
---|
1474 | if origname: |
---|
1475 | if self._props.setdefault(origname.lower(), rec) is not rec: |
---|
1476 | self._props[origname.lower()] = (type_, self.__ambiguous_processor(origname), 0) |
---|
1477 | |
---|
1478 | self.keys.append(colname) |
---|
1479 | self._props[i] = rec |
---|
1480 | if obj: |
---|
1481 | for o in obj: |
---|
1482 | self._props[o] = rec |
---|
1483 | |
---|
1484 | if self._echo: |
---|
1485 | self.context.engine.logger.debug( |
---|
1486 | "Col " + repr(tuple(x[0] for x in metadata))) |
---|
1487 | |
---|
1488 | def __key_fallback(self): |
---|
1489 | # create a closure without 'self' to avoid circular references |
---|
1490 | props = self._props |
---|
1491 | |
---|
1492 | def fallback(key): |
---|
1493 | if isinstance(key, basestring): |
---|
1494 | key = key.lower() |
---|
1495 | if key in props: |
---|
1496 | return props[key] |
---|
1497 | |
---|
1498 | # fallback for targeting a ColumnElement to a textual expression |
---|
1499 | # this is a rare use case which only occurs when matching text() |
---|
1500 | # constructs to ColumnElements |
---|
1501 | if isinstance(key, expression.ColumnElement): |
---|
1502 | if key._label and key._label.lower() in props: |
---|
1503 | return props[key._label.lower()] |
---|
1504 | elif hasattr(key, 'name') and key.name.lower() in props: |
---|
1505 | return props[key.name.lower()] |
---|
1506 | |
---|
1507 | raise exc.NoSuchColumnError("Could not locate column in row for column '%s'" % (str(key))) |
---|
1508 | return fallback |
---|
1509 | |
---|
1510 | def __ambiguous_processor(self, colname): |
---|
1511 | def process(value): |
---|
1512 | raise exc.InvalidRequestError("Ambiguous column name '%s' in result set! " |
---|
1513 | "try 'use_labels' option on select statement." % colname) |
---|
1514 | return process |
---|
1515 | |
---|
1516 | def close(self): |
---|
1517 | """Close this ResultProxy. |
---|
1518 | |
---|
1519 | Closes the underlying DBAPI cursor corresponding to the execution. |
---|
1520 | |
---|
1521 | If this ResultProxy was generated from an implicit execution, |
---|
1522 | the underlying Connection will also be closed (returns the |
---|
1523 | underlying DBAPI connection to the connection pool.) |
---|
1524 | |
---|
1525 | This method is called automatically when: |
---|
1526 | |
---|
1527 | * all result rows are exhausted using the fetchXXX() methods. |
---|
1528 | * cursor.description is None. |
---|
1529 | |
---|
1530 | """ |
---|
1531 | if not self.closed: |
---|
1532 | self.closed = True |
---|
1533 | self.cursor.close() |
---|
1534 | if self.connection.should_close_with_result: |
---|
1535 | self.connection.close() |
---|
1536 | |
---|
1537 | def _has_key(self, row, key): |
---|
1538 | try: |
---|
1539 | # _key_cache uses __missing__ in 2.5, so not much alternative |
---|
1540 | # to catching KeyError |
---|
1541 | self._props[key] |
---|
1542 | return True |
---|
1543 | except KeyError: |
---|
1544 | return False |
---|
1545 | |
---|
1546 | def __iter__(self): |
---|
1547 | while True: |
---|
1548 | row = self.fetchone() |
---|
1549 | if row is None: |
---|
1550 | raise StopIteration |
---|
1551 | else: |
---|
1552 | yield row |
---|
1553 | |
---|
1554 | def last_inserted_ids(self): |
---|
1555 | """Return ``last_inserted_ids()`` from the underlying ExecutionContext. |
---|
1556 | |
---|
1557 | See ExecutionContext for details. |
---|
1558 | |
---|
1559 | """ |
---|
1560 | return self.context.last_inserted_ids() |
---|
1561 | |
---|
1562 | def last_updated_params(self): |
---|
1563 | """Return ``last_updated_params()`` from the underlying ExecutionContext. |
---|
1564 | |
---|
1565 | See ExecutionContext for details. |
---|
1566 | |
---|
1567 | """ |
---|
1568 | return self.context.last_updated_params() |
---|
1569 | |
---|
1570 | def last_inserted_params(self): |
---|
1571 | """Return ``last_inserted_params()`` from the underlying ExecutionContext. |
---|
1572 | |
---|
1573 | See ExecutionContext for details. |
---|
1574 | |
---|
1575 | """ |
---|
1576 | return self.context.last_inserted_params() |
---|
1577 | |
---|
1578 | def lastrow_has_defaults(self): |
---|
1579 | """Return ``lastrow_has_defaults()`` from the underlying ExecutionContext. |
---|
1580 | |
---|
1581 | See ExecutionContext for details. |
---|
1582 | |
---|
1583 | """ |
---|
1584 | return self.context.lastrow_has_defaults() |
---|
1585 | |
---|
1586 | def postfetch_cols(self): |
---|
1587 | """Return ``postfetch_cols()`` from the underlying ExecutionContext. |
---|
1588 | |
---|
1589 | See ExecutionContext for details. |
---|
1590 | |
---|
1591 | """ |
---|
1592 | return self.context.postfetch_cols |
---|
1593 | |
---|
1594 | def prefetch_cols(self): |
---|
1595 | return self.context.prefetch_cols |
---|
1596 | |
---|
1597 | def supports_sane_rowcount(self): |
---|
1598 | """Return ``supports_sane_rowcount`` from the dialect.""" |
---|
1599 | |
---|
1600 | return self.dialect.supports_sane_rowcount |
---|
1601 | |
---|
1602 | def supports_sane_multi_rowcount(self): |
---|
1603 | """Return ``supports_sane_multi_rowcount`` from the dialect.""" |
---|
1604 | |
---|
1605 | return self.dialect.supports_sane_multi_rowcount |
---|
1606 | |
---|
1607 | def _get_col(self, row, key): |
---|
1608 | try: |
---|
1609 | type_, processor, index = self._props[key] |
---|
1610 | except TypeError: |
---|
1611 | # the 'slice' use case is very infrequent, |
---|
1612 | # so we use an exception catch to reduce conditionals in _get_col |
---|
1613 | if isinstance(key, slice): |
---|
1614 | indices = key.indices(len(row)) |
---|
1615 | return tuple(self._get_col(row, i) for i in xrange(*indices)) |
---|
1616 | else: |
---|
1617 | raise |
---|
1618 | |
---|
1619 | if processor: |
---|
1620 | return processor(row[index]) |
---|
1621 | else: |
---|
1622 | return row[index] |
---|
1623 | |
---|
1624 | def _fetchone_impl(self): |
---|
1625 | return self.cursor.fetchone() |
---|
1626 | |
---|
1627 | def _fetchmany_impl(self, size=None): |
---|
1628 | return self.cursor.fetchmany(size) |
---|
1629 | |
---|
1630 | def _fetchall_impl(self): |
---|
1631 | return self.cursor.fetchall() |
---|
1632 | |
---|
1633 | def fetchall(self): |
---|
1634 | """Fetch all rows, just like DB-API ``cursor.fetchall()``.""" |
---|
1635 | |
---|
1636 | try: |
---|
1637 | process_row = self._process_row |
---|
1638 | l = [process_row(self, row) for row in self._fetchall_impl()] |
---|
1639 | self.close() |
---|
1640 | return l |
---|
1641 | except Exception, e: |
---|
1642 | self.connection._handle_dbapi_exception(e, None, None, self.cursor, self.context) |
---|
1643 | raise |
---|
1644 | |
---|
1645 | def fetchmany(self, size=None): |
---|
1646 | """Fetch many rows, just like DB-API ``cursor.fetchmany(size=cursor.arraysize)``.""" |
---|
1647 | |
---|
1648 | try: |
---|
1649 | process_row = self._process_row |
---|
1650 | l = [process_row(self, row) for row in self._fetchmany_impl(size)] |
---|
1651 | if len(l) == 0: |
---|
1652 | self.close() |
---|
1653 | return l |
---|
1654 | except Exception, e: |
---|
1655 | self.connection._handle_dbapi_exception(e, None, None, self.cursor, self.context) |
---|
1656 | raise |
---|
1657 | |
---|
1658 | def fetchone(self): |
---|
1659 | """Fetch one row, just like DB-API ``cursor.fetchone()``.""" |
---|
1660 | try: |
---|
1661 | row = self._fetchone_impl() |
---|
1662 | if row is not None: |
---|
1663 | return self._process_row(self, row) |
---|
1664 | else: |
---|
1665 | self.close() |
---|
1666 | return None |
---|
1667 | except Exception, e: |
---|
1668 | self.connection._handle_dbapi_exception(e, None, None, self.cursor, self.context) |
---|
1669 | raise |
---|
1670 | |
---|
1671 | def scalar(self): |
---|
1672 | """Fetch the first column of the first row, and close the result set.""" |
---|
1673 | try: |
---|
1674 | row = self._fetchone_impl() |
---|
1675 | except Exception, e: |
---|
1676 | self.connection._handle_dbapi_exception(e, None, None, self.cursor, self.context) |
---|
1677 | raise |
---|
1678 | |
---|
1679 | try: |
---|
1680 | if row is not None: |
---|
1681 | return self._process_row(self, row)[0] |
---|
1682 | else: |
---|
1683 | return None |
---|
1684 | finally: |
---|
1685 | self.close() |
---|
1686 | |
---|
1687 | class BufferedRowResultProxy(ResultProxy): |
---|
1688 | """A ResultProxy with row buffering behavior. |
---|
1689 | |
---|
1690 | ``ResultProxy`` that buffers the contents of a selection of rows |
---|
1691 | before ``fetchone()`` is called. This is to allow the results of |
---|
1692 | ``cursor.description`` to be available immediately, when |
---|
1693 | interfacing with a DB-API that requires rows to be consumed before |
---|
1694 | this information is available (currently psycopg2, when used with |
---|
1695 | server-side cursors). |
---|
1696 | |
---|
1697 | The pre-fetching behavior fetches only one row initially, and then |
---|
1698 | grows its buffer size by a fixed amount with each successive need |
---|
1699 | for additional rows up to a size of 100. |
---|
1700 | |
---|
1701 | """ |
---|
1702 | |
---|
1703 | def _init_metadata(self): |
---|
1704 | self.__buffer_rows() |
---|
1705 | super(BufferedRowResultProxy, self)._init_metadata() |
---|
1706 | |
---|
1707 | # this is a "growth chart" for the buffering of rows. |
---|
1708 | # each successive __buffer_rows call will use the next |
---|
1709 | # value in the list for the buffer size until the max |
---|
1710 | # is reached |
---|
1711 | size_growth = { |
---|
1712 | 1 : 5, |
---|
1713 | 5 : 10, |
---|
1714 | 10 : 20, |
---|
1715 | 20 : 50, |
---|
1716 | 50 : 100 |
---|
1717 | } |
---|
1718 | |
---|
1719 | def __buffer_rows(self): |
---|
1720 | size = getattr(self, '_bufsize', 1) |
---|
1721 | self.__rowbuffer = self.cursor.fetchmany(size) |
---|
1722 | self._bufsize = self.size_growth.get(size, size) |
---|
1723 | |
---|
1724 | def _fetchone_impl(self): |
---|
1725 | if self.closed: |
---|
1726 | return None |
---|
1727 | if len(self.__rowbuffer) == 0: |
---|
1728 | self.__buffer_rows() |
---|
1729 | if len(self.__rowbuffer) == 0: |
---|
1730 | return None |
---|
1731 | return self.__rowbuffer.pop(0) |
---|
1732 | |
---|
1733 | def _fetchmany_impl(self, size=None): |
---|
1734 | result = [] |
---|
1735 | for x in range(0, size): |
---|
1736 | row = self._fetchone_impl() |
---|
1737 | if row is None: |
---|
1738 | break |
---|
1739 | result.append(row) |
---|
1740 | return result |
---|
1741 | |
---|
1742 | def _fetchall_impl(self): |
---|
1743 | return self.__rowbuffer + list(self.cursor.fetchall()) |
---|
1744 | |
---|
1745 | class BufferedColumnResultProxy(ResultProxy): |
---|
1746 | """A ResultProxy with column buffering behavior. |
---|
1747 | |
---|
1748 | ``ResultProxy`` that loads all columns into memory each time |
---|
1749 | fetchone() is called. If fetchmany() or fetchall() are called, |
---|
1750 | the full grid of results is fetched. This is to operate with |
---|
1751 | databases where result rows contain "live" results that fall out |
---|
1752 | of scope unless explicitly fetched. Currently this includes just |
---|
1753 | cx_Oracle LOB objects, but this behavior is known to exist in |
---|
1754 | other DB-APIs as well (Pygresql, currently unsupported). |
---|
1755 | |
---|
1756 | """ |
---|
1757 | |
---|
1758 | _process_row = BufferedColumnRow |
---|
1759 | |
---|
1760 | def _get_col(self, row, key): |
---|
1761 | try: |
---|
1762 | rec = self._props[key] |
---|
1763 | return row[rec[2]] |
---|
1764 | except TypeError: |
---|
1765 | # the 'slice' use case is very infrequent, |
---|
1766 | # so we use an exception catch to reduce conditionals in _get_col |
---|
1767 | if isinstance(key, slice): |
---|
1768 | indices = key.indices(len(row)) |
---|
1769 | return tuple(self._get_col(row, i) for i in xrange(*indices)) |
---|
1770 | else: |
---|
1771 | raise |
---|
1772 | |
---|
1773 | def fetchall(self): |
---|
1774 | l = [] |
---|
1775 | while True: |
---|
1776 | row = self.fetchone() |
---|
1777 | if row is None: |
---|
1778 | break |
---|
1779 | l.append(row) |
---|
1780 | return l |
---|
1781 | |
---|
1782 | def fetchmany(self, size=None): |
---|
1783 | if size is None: |
---|
1784 | return self.fetchall() |
---|
1785 | l = [] |
---|
1786 | for i in xrange(size): |
---|
1787 | row = self.fetchone() |
---|
1788 | if row is None: |
---|
1789 | break |
---|
1790 | l.append(row) |
---|
1791 | return l |
---|
1792 | |
---|
1793 | |
---|
1794 | class SchemaIterator(schema.SchemaVisitor): |
---|
1795 | """A visitor that can gather text into a buffer and execute the contents of the buffer.""" |
---|
1796 | |
---|
1797 | def __init__(self, connection): |
---|
1798 | """Construct a new SchemaIterator.""" |
---|
1799 | |
---|
1800 | self.connection = connection |
---|
1801 | self.buffer = StringIO.StringIO() |
---|
1802 | |
---|
1803 | def append(self, s): |
---|
1804 | """Append content to the SchemaIterator's query buffer.""" |
---|
1805 | |
---|
1806 | self.buffer.write(s) |
---|
1807 | |
---|
1808 | def execute(self): |
---|
1809 | """Execute the contents of the SchemaIterator's buffer.""" |
---|
1810 | |
---|
1811 | try: |
---|
1812 | return self.connection.execute(self.buffer.getvalue()) |
---|
1813 | finally: |
---|
1814 | self.buffer.truncate(0) |
---|
1815 | |
---|
1816 | class DefaultRunner(schema.SchemaVisitor): |
---|
1817 | """A visitor which accepts ColumnDefault objects, produces the |
---|
1818 | dialect-specific SQL corresponding to their execution, and |
---|
1819 | executes the SQL, returning the result value. |
---|
1820 | |
---|
1821 | DefaultRunners are used internally by Engines and Dialects. |
---|
1822 | Specific database modules should provide their own subclasses of |
---|
1823 | DefaultRunner to allow database-specific behavior. |
---|
1824 | |
---|
1825 | """ |
---|
1826 | |
---|
1827 | def __init__(self, context): |
---|
1828 | self.context = context |
---|
1829 | self.dialect = context.dialect |
---|
1830 | self.cursor = context.cursor |
---|
1831 | |
---|
1832 | def get_column_default(self, column): |
---|
1833 | if column.default is not None: |
---|
1834 | return self.traverse_single(column.default) |
---|
1835 | else: |
---|
1836 | return None |
---|
1837 | |
---|
1838 | def get_column_onupdate(self, column): |
---|
1839 | if column.onupdate is not None: |
---|
1840 | return self.traverse_single(column.onupdate) |
---|
1841 | else: |
---|
1842 | return None |
---|
1843 | |
---|
1844 | def visit_passive_default(self, default): |
---|
1845 | return None |
---|
1846 | |
---|
1847 | def visit_sequence(self, seq): |
---|
1848 | return None |
---|
1849 | |
---|
1850 | def exec_default_sql(self, default): |
---|
1851 | conn = self.context.connection |
---|
1852 | c = expression.select([default.arg]).compile(bind=conn) |
---|
1853 | return conn._execute_compiled(c, (), {}).scalar() |
---|
1854 | |
---|
1855 | def execute_string(self, stmt, params=None): |
---|
1856 | """execute a string statement, using the raw cursor, and return a scalar result.""" |
---|
1857 | |
---|
1858 | conn = self.context._connection |
---|
1859 | if isinstance(stmt, unicode) and not self.dialect.supports_unicode_statements: |
---|
1860 | stmt = stmt.encode(self.dialect.encoding) |
---|
1861 | conn._cursor_execute(self.cursor, stmt, params) |
---|
1862 | return self.cursor.fetchone()[0] |
---|
1863 | |
---|
1864 | def visit_column_onupdate(self, onupdate): |
---|
1865 | if isinstance(onupdate.arg, expression.ClauseElement): |
---|
1866 | return self.exec_default_sql(onupdate) |
---|
1867 | elif util.callable(onupdate.arg): |
---|
1868 | return onupdate.arg(self.context) |
---|
1869 | else: |
---|
1870 | return onupdate.arg |
---|
1871 | |
---|
1872 | def visit_column_default(self, default): |
---|
1873 | if isinstance(default.arg, expression.ClauseElement): |
---|
1874 | return self.exec_default_sql(default) |
---|
1875 | elif util.callable(default.arg): |
---|
1876 | return default.arg(self.context) |
---|
1877 | else: |
---|
1878 | return default.arg |
---|
1879 | |
---|
1880 | |
---|
1881 | def connection_memoize(key): |
---|
1882 | """Decorator, memoize a function in a connection.info stash. |
---|
1883 | |
---|
1884 | Only applicable to functions which take no arguments other than a |
---|
1885 | connection. The memo will be stored in ``connection.info[key]``. |
---|
1886 | |
---|
1887 | """ |
---|
1888 | @util.decorator |
---|
1889 | def decorated(fn, self, connection): |
---|
1890 | connection = connection.connect() |
---|
1891 | try: |
---|
1892 | return connection.info[key] |
---|
1893 | except KeyError: |
---|
1894 | connection.info[key] = val = fn(self, connection) |
---|
1895 | return val |
---|
1896 | |
---|
1897 | return decorated |
---|