1 | # dynamic.py |
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2 | # Copyright (C) the SQLAlchemy authors and contributors |
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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 | """Dynamic collection API. |
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8 | |
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9 | Dynamic collections act like Query() objects for read operations and support |
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10 | basic add/delete mutation. |
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11 | |
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12 | """ |
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13 | |
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14 | from sqlalchemy import log, util |
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15 | import sqlalchemy.exceptions as sa_exc |
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16 | |
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17 | from sqlalchemy.orm import ( |
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18 | attributes, object_session, util as mapperutil, strategies, |
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19 | ) |
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20 | from sqlalchemy.orm.query import Query |
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21 | from sqlalchemy.orm.util import _state_has_identity, has_identity |
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22 | from sqlalchemy.orm import attributes, collections |
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23 | |
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24 | class DynaLoader(strategies.AbstractRelationLoader): |
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25 | def init_class_attribute(self, mapper): |
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26 | self.is_class_level = True |
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27 | |
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28 | strategies._register_attribute(self, |
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29 | mapper, |
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30 | useobject=True, |
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31 | impl_class=DynamicAttributeImpl, |
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32 | target_mapper=self.parent_property.mapper, |
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33 | order_by=self.parent_property.order_by, |
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34 | query_class=self.parent_property.query_class |
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35 | ) |
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36 | |
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37 | def create_row_processor(self, selectcontext, path, mapper, row, adapter): |
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38 | return (None, None) |
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39 | |
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40 | log.class_logger(DynaLoader) |
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41 | |
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42 | class DynamicAttributeImpl(attributes.AttributeImpl): |
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43 | uses_objects = True |
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44 | accepts_scalar_loader = False |
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45 | |
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46 | def __init__(self, class_, key, typecallable, |
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47 | target_mapper, order_by, query_class=None, **kwargs): |
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48 | super(DynamicAttributeImpl, self).__init__(class_, key, typecallable, **kwargs) |
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49 | self.target_mapper = target_mapper |
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50 | self.order_by = order_by |
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51 | if not query_class: |
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52 | self.query_class = AppenderQuery |
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53 | elif AppenderMixin in query_class.mro(): |
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54 | self.query_class = query_class |
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55 | else: |
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56 | self.query_class = mixin_user_query(query_class) |
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57 | |
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58 | def get(self, state, dict_, passive=False): |
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59 | if passive: |
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60 | return self._get_collection_history(state, passive=True).added_items |
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61 | else: |
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62 | return self.query_class(self, state) |
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63 | |
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64 | def get_collection(self, state, dict_, user_data=None, passive=True): |
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65 | if passive: |
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66 | return self._get_collection_history(state, passive=passive).added_items |
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67 | else: |
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68 | history = self._get_collection_history(state, passive=passive) |
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69 | return history.added_items + history.unchanged_items |
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70 | |
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71 | def fire_append_event(self, state, dict_, value, initiator): |
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72 | collection_history = self._modified_event(state, dict_) |
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73 | collection_history.added_items.append(value) |
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74 | |
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75 | for ext in self.extensions: |
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76 | ext.append(state, value, initiator or self) |
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77 | |
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78 | if self.trackparent and value is not None: |
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79 | self.sethasparent(attributes.instance_state(value), True) |
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80 | |
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81 | def fire_remove_event(self, state, dict_, value, initiator): |
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82 | collection_history = self._modified_event(state, dict_) |
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83 | collection_history.deleted_items.append(value) |
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84 | |
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85 | if self.trackparent and value is not None: |
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86 | self.sethasparent(attributes.instance_state(value), False) |
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87 | |
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88 | for ext in self.extensions: |
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89 | ext.remove(state, value, initiator or self) |
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90 | |
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91 | def _modified_event(self, state, dict_): |
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92 | |
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93 | if self.key not in state.committed_state: |
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94 | state.committed_state[self.key] = CollectionHistory(self, state) |
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95 | |
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96 | state.modified_event(dict_, self, False, attributes.NEVER_SET, passive=attributes.PASSIVE_NO_INITIALIZE) |
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97 | |
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98 | # this is a hack to allow the _base.ComparableEntity fixture |
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99 | # to work |
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100 | dict_[self.key] = True |
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101 | return state.committed_state[self.key] |
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102 | |
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103 | def set(self, state, dict_, value, initiator, passive=attributes.PASSIVE_OFF): |
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104 | if initiator is self: |
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105 | return |
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106 | |
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107 | self._set_iterable(state, dict_, value) |
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108 | |
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109 | def _set_iterable(self, state, dict_, iterable, adapter=None): |
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110 | |
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111 | collection_history = self._modified_event(state, dict_) |
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112 | new_values = list(iterable) |
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113 | |
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114 | if _state_has_identity(state): |
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115 | old_collection = list(self.get(state, dict_)) |
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116 | else: |
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117 | old_collection = [] |
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118 | |
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119 | collections.bulk_replace(new_values, DynCollectionAdapter(self, state, old_collection), DynCollectionAdapter(self, state, new_values)) |
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120 | |
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121 | def delete(self, *args, **kwargs): |
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122 | raise NotImplementedError() |
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123 | |
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124 | def get_history(self, state, dict_, passive=False): |
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125 | c = self._get_collection_history(state, passive) |
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126 | return attributes.History(c.added_items, c.unchanged_items, c.deleted_items) |
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127 | |
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128 | def _get_collection_history(self, state, passive=False): |
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129 | if self.key in state.committed_state: |
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130 | c = state.committed_state[self.key] |
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131 | else: |
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132 | c = CollectionHistory(self, state) |
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133 | |
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134 | if not passive: |
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135 | return CollectionHistory(self, state, apply_to=c) |
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136 | else: |
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137 | return c |
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138 | |
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139 | def append(self, state, dict_, value, initiator, passive=False): |
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140 | if initiator is not self: |
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141 | self.fire_append_event(state, dict_, value, initiator) |
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142 | |
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143 | def remove(self, state, dict_, value, initiator, passive=False): |
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144 | if initiator is not self: |
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145 | self.fire_remove_event(state, dict_, value, initiator) |
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146 | |
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147 | class DynCollectionAdapter(object): |
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148 | """the dynamic analogue to orm.collections.CollectionAdapter""" |
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149 | |
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150 | def __init__(self, attr, owner_state, data): |
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151 | self.attr = attr |
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152 | self.state = owner_state |
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153 | self.data = data |
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154 | |
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155 | def __iter__(self): |
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156 | return iter(self.data) |
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157 | |
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158 | def append_with_event(self, item, initiator=None): |
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159 | self.attr.append(self.state, self.state.dict, item, initiator) |
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160 | |
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161 | def remove_with_event(self, item, initiator=None): |
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162 | self.attr.remove(self.state, self.state.dict, item, initiator) |
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163 | |
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164 | def append_without_event(self, item): |
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165 | pass |
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166 | |
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167 | def remove_without_event(self, item): |
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168 | pass |
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169 | |
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170 | class AppenderMixin(object): |
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171 | query_class = None |
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172 | |
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173 | def __init__(self, attr, state): |
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174 | Query.__init__(self, attr.target_mapper, None) |
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175 | self.instance = state.obj() |
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176 | self.attr = attr |
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177 | |
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178 | def __session(self): |
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179 | sess = object_session(self.instance) |
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180 | if sess is not None and self.autoflush and sess.autoflush and self.instance in sess: |
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181 | sess.flush() |
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182 | if not has_identity(self.instance): |
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183 | return None |
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184 | else: |
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185 | return sess |
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186 | |
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187 | def session(self): |
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188 | return self.__session() |
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189 | session = property(session, lambda s, x:None) |
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190 | |
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191 | def __iter__(self): |
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192 | sess = self.__session() |
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193 | if sess is None: |
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194 | return iter(self.attr._get_collection_history( |
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195 | attributes.instance_state(self.instance), |
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196 | passive=True).added_items) |
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197 | else: |
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198 | return iter(self._clone(sess)) |
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199 | |
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200 | def __getitem__(self, index): |
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201 | sess = self.__session() |
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202 | if sess is None: |
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203 | return self.attr._get_collection_history( |
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204 | attributes.instance_state(self.instance), |
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205 | passive=True).added_items.__getitem__(index) |
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206 | else: |
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207 | return self._clone(sess).__getitem__(index) |
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208 | |
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209 | def count(self): |
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210 | sess = self.__session() |
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211 | if sess is None: |
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212 | return len(self.attr._get_collection_history( |
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213 | attributes.instance_state(self.instance), |
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214 | passive=True).added_items) |
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215 | else: |
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216 | return self._clone(sess).count() |
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217 | |
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218 | def _clone(self, sess=None): |
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219 | # note we're returning an entirely new Query class instance |
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220 | # here without any assignment capabilities; the class of this |
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221 | # query is determined by the session. |
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222 | instance = self.instance |
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223 | if sess is None: |
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224 | sess = object_session(instance) |
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225 | if sess is None: |
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226 | raise sa_exc.UnboundExecutionError( |
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227 | "Parent instance %s is not bound to a Session, and no " |
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228 | "contextual session is established; lazy load operation " |
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229 | "of attribute '%s' cannot proceed" % ( |
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230 | mapperutil.instance_str(instance), self.attr.key)) |
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231 | |
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232 | if self.query_class: |
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233 | query = self.query_class(self.attr.target_mapper, session=sess) |
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234 | else: |
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235 | query = sess.query(self.attr.target_mapper) |
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236 | query = query.with_parent(instance, self.attr.key) |
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237 | |
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238 | if self.attr.order_by: |
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239 | query = query.order_by(self.attr.order_by) |
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240 | return query |
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241 | |
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242 | def append(self, item): |
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243 | self.attr.append(attributes.instance_state(self.instance), attributes.instance_dict(self.instance), item, None) |
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244 | |
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245 | def remove(self, item): |
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246 | self.attr.remove(attributes.instance_state(self.instance), attributes.instance_dict(self.instance), item, None) |
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247 | |
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248 | |
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249 | class AppenderQuery(AppenderMixin, Query): |
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250 | """A dynamic query that supports basic collection storage operations.""" |
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251 | |
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252 | |
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253 | def mixin_user_query(cls): |
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254 | """Return a new class with AppenderQuery functionality layered over.""" |
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255 | name = 'Appender' + cls.__name__ |
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256 | return type(name, (AppenderMixin, cls), {'query_class': cls}) |
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257 | |
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258 | class CollectionHistory(object): |
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259 | """Overrides AttributeHistory to receive append/remove events directly.""" |
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260 | |
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261 | def __init__(self, attr, state, apply_to=None): |
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262 | if apply_to: |
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263 | deleted = util.IdentitySet(apply_to.deleted_items) |
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264 | added = apply_to.added_items |
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265 | coll = AppenderQuery(attr, state).autoflush(False) |
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266 | self.unchanged_items = [o for o in util.IdentitySet(coll) if o not in deleted] |
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267 | self.added_items = apply_to.added_items |
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268 | self.deleted_items = apply_to.deleted_items |
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269 | else: |
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270 | self.deleted_items = [] |
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271 | self.added_items = [] |
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272 | self.unchanged_items = [] |
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273 | |
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