[3] | 1 | """ |
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| 2 | Schema module providing common schema operations. |
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| 3 | """ |
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| 4 | import re |
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| 5 | import sqlalchemy |
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| 6 | from migrate.changeset.databases.visitor import get_engine_visitor |
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| 7 | |
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| 8 | __all__ = [ |
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| 9 | 'create_column', |
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| 10 | 'drop_column', |
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| 11 | 'alter_column', |
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| 12 | 'rename_table', |
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| 13 | 'rename_index', |
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| 14 | ] |
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| 15 | |
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| 16 | |
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| 17 | def create_column(column, table=None, *p, **k): |
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| 18 | if table is not None: |
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| 19 | return table.create_column(column, *p, **k) |
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| 20 | return column.create(*p, **k) |
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| 21 | |
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| 22 | |
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| 23 | def drop_column(column, table=None, *p, **k): |
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| 24 | if table is not None: |
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| 25 | return table.drop_column(column, *p, **k) |
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| 26 | return column.drop(*p, **k) |
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| 27 | |
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| 28 | |
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| 29 | def _to_table(table, engine=None): |
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| 30 | if isinstance(table, sqlalchemy.Table): |
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| 31 | return table |
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| 32 | # Given: table name, maybe an engine |
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| 33 | meta = sqlalchemy.MetaData() |
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| 34 | if engine is not None: |
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| 35 | meta.bind = engine |
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| 36 | return sqlalchemy.Table(table, meta) |
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| 37 | |
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| 38 | |
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| 39 | def _to_index(index, table=None, engine=None): |
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| 40 | if isinstance(index, sqlalchemy.Index): |
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| 41 | return index |
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| 42 | # Given: index name; table name required |
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| 43 | table = _to_table(table, engine) |
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| 44 | ret = sqlalchemy.Index(index) |
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| 45 | ret.table = table |
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| 46 | return ret |
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| 47 | |
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| 48 | |
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| 49 | def rename_table(table, name, engine=None): |
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| 50 | """Rename a table, given the table's current name and the new |
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| 51 | name.""" |
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| 52 | table = _to_table(table, engine) |
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| 53 | table.rename(name) |
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| 54 | |
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| 55 | |
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| 56 | def rename_index(index, name, table=None, engine=None): |
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| 57 | """Rename an index. |
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| 58 | |
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| 59 | Takes an index name/object, a table name/object, and an |
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| 60 | engine. Engine and table aren't required if an index object is |
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| 61 | given. |
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| 62 | """ |
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| 63 | index = _to_index(index, table, engine) |
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| 64 | index.rename(name) |
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| 65 | |
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| 66 | |
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| 67 | def _engine_run_visitor(engine, visitorcallable, element, **kwargs): |
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| 68 | conn = engine.connect() |
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| 69 | try: |
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| 70 | element.accept_schema_visitor(visitorcallable(engine.dialect, |
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| 71 | connection=conn)) |
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| 72 | finally: |
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| 73 | conn.close() |
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| 74 | |
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| 75 | |
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| 76 | def alter_column(*p, **k): |
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| 77 | """Alter a column. |
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| 78 | |
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| 79 | Parameters: column name, table name, an engine, and the properties |
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| 80 | of that column to change |
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| 81 | """ |
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| 82 | if len(p) and isinstance(p[0], sqlalchemy.Column): |
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| 83 | col = p[0] |
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| 84 | else: |
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| 85 | col = None |
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| 86 | if 'table' not in k: |
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| 87 | k['table'] = col.table |
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| 88 | if 'engine' not in k: |
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| 89 | k['engine'] = k['table'].bind |
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| 90 | engine = k['engine'] |
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| 91 | delta = _ColumnDelta(*p, **k) |
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| 92 | visitorcallable = get_engine_visitor(engine, 'schemachanger') |
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| 93 | _engine_run_visitor(engine, visitorcallable, delta) |
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| 94 | |
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| 95 | # Update column |
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| 96 | if col is not None: |
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| 97 | # Special case: change column key on rename, if key not |
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| 98 | # explicit |
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| 99 | # |
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| 100 | # Used by SA : table.c.[key] |
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| 101 | # |
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| 102 | # This fails if the key was explit AND equal to the column |
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| 103 | # name. (It changes the key name when it shouldn't.) |
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| 104 | # |
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| 105 | # Not much we can do about it. |
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| 106 | if 'name' in delta.keys(): |
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| 107 | if (col.name == col.key): |
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| 108 | newname = delta['name'] |
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| 109 | del col.table.c[col.key] |
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| 110 | setattr(col, 'key', newname) |
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| 111 | col.table.c[col.key] = col |
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| 112 | # Change all other attrs |
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| 113 | for key, val in delta.iteritems(): |
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| 114 | setattr(col, key, val) |
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| 115 | |
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| 116 | |
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| 117 | def _normalize_table(column, table): |
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| 118 | if table is not None: |
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| 119 | if table is not column.table: |
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| 120 | # This is a bit of a hack: we end up with dupe PK columns here |
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| 121 | pk_names = map(lambda c: c.name, table.primary_key) |
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| 122 | if column.primary_key and pk_names.count(column.name): |
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| 123 | index = pk_names.index(column_name) |
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| 124 | del table.primary_key[index] |
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| 125 | table.append_column(column) |
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| 126 | return column.table |
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| 127 | |
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| 128 | |
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| 129 | class _WrapRename(object): |
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| 130 | |
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| 131 | def __init__(self, item, name): |
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| 132 | self.item = item |
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| 133 | self.name = name |
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| 134 | |
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| 135 | def accept_schema_visitor(self, visitor): |
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| 136 | if isinstance(self.item, sqlalchemy.Table): |
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| 137 | suffix = 'table' |
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| 138 | elif isinstance(self.item, sqlalchemy.Column): |
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| 139 | suffix = 'column' |
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| 140 | elif isinstance(self.item, sqlalchemy.Index): |
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| 141 | suffix = 'index' |
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| 142 | funcname = 'visit_%s' % suffix |
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| 143 | func = getattr(visitor, funcname) |
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| 144 | param = self.item, self.name |
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| 145 | return func(param) |
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| 146 | |
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| 147 | |
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| 148 | class _ColumnDelta(dict): |
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| 149 | """Extracts the differences between two columns/column-parameters""" |
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| 150 | |
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| 151 | def __init__(self, *p, **k): |
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| 152 | """Extract ALTER-able differences from two columns. |
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| 153 | |
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| 154 | May receive parameters arranged in several different ways: |
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| 155 | * old_column_object,new_column_object,*parameters Identifies |
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| 156 | attributes that differ between the two columns. |
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| 157 | Parameters specified outside of either column are always |
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| 158 | executed and override column differences. |
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| 159 | * column_object,[current_name,]*parameters Parameters |
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| 160 | specified are changed; table name is extracted from column |
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| 161 | object. Name is changed to column_object.name from |
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| 162 | current_name, if current_name is specified. If not |
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| 163 | specified, name is unchanged. |
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| 164 | * current_name,table,*parameters 'table' may be either an |
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| 165 | object or a name |
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| 166 | """ |
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| 167 | # Things are initialized differently depending on how many column |
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| 168 | # parameters are given. Figure out how many and call the appropriate |
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| 169 | # method. |
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| 170 | if len(p) >= 1 and isinstance(p[0], sqlalchemy.Column): |
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| 171 | # At least one column specified |
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| 172 | if len(p) >= 2 and isinstance(p[1], sqlalchemy.Column): |
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| 173 | # Two columns specified |
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| 174 | func = self._init_2col |
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| 175 | else: |
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| 176 | # Exactly one column specified |
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| 177 | func = self._init_1col |
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| 178 | else: |
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| 179 | # Zero columns specified |
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| 180 | func = self._init_0col |
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| 181 | diffs = func(*p, **k) |
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| 182 | self._set_diffs(diffs) |
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| 183 | # Column attributes that can be altered |
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| 184 | diff_keys = ('name', 'type', 'nullable', 'default', 'server_default', |
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| 185 | 'primary_key', 'foreign_key') |
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| 186 | |
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| 187 | def _get_table_name(self): |
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| 188 | if isinstance(self._table, basestring): |
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| 189 | ret = self._table |
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| 190 | else: |
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| 191 | ret = self._table.name |
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| 192 | return ret |
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| 193 | table_name = property(_get_table_name) |
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| 194 | |
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| 195 | def _get_table(self): |
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| 196 | if isinstance(self._table, basestring): |
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| 197 | ret = None |
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| 198 | else: |
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| 199 | ret = self._table |
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| 200 | return ret |
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| 201 | table = property(_get_table) |
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| 202 | |
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| 203 | def _init_0col(self, current_name, *p, **k): |
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| 204 | p, k = self._init_normalize_params(p, k) |
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| 205 | table = k.pop('table') |
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| 206 | self.current_name = current_name |
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| 207 | self._table = table |
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| 208 | return k |
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| 209 | |
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| 210 | def _init_1col(self, col, *p, **k): |
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| 211 | p, k = self._init_normalize_params(p, k) |
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| 212 | self._table = k.pop('table', None) or col.table |
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| 213 | self.result_column = col.copy() |
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| 214 | if 'current_name' in k: |
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| 215 | # Renamed |
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| 216 | self.current_name = k.pop('current_name') |
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| 217 | k.setdefault('name', col.name) |
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| 218 | else: |
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| 219 | self.current_name = col.name |
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| 220 | return k |
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| 221 | |
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| 222 | def _init_2col(self, start_col, end_col, *p, **k): |
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| 223 | p, k = self._init_normalize_params(p, k) |
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| 224 | self.result_column = start_col.copy() |
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| 225 | self._table = k.pop('table', None) or start_col.table \ |
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| 226 | or end_col.table |
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| 227 | self.current_name = start_col.name |
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| 228 | for key in ('name', 'nullable', 'default', 'server_default', |
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| 229 | 'primary_key', 'foreign_key'): |
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| 230 | val = getattr(end_col, key, None) |
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| 231 | if getattr(start_col, key, None) != val: |
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| 232 | k.setdefault(key, val) |
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| 233 | if not self.column_types_eq(start_col.type, end_col.type): |
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| 234 | k.setdefault('type', end_col.type) |
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| 235 | return k |
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| 236 | |
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| 237 | def _init_normalize_params(self, p, k): |
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| 238 | p = list(p) |
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| 239 | if len(p): |
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| 240 | k.setdefault('name', p.pop(0)) |
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| 241 | if len(p): |
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| 242 | k.setdefault('type', p.pop(0)) |
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| 243 | # TODO: sequences? FKs? |
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| 244 | return p, k |
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| 245 | |
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| 246 | def _set_diffs(self, diffs): |
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| 247 | for key in self.diff_keys: |
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| 248 | if key in diffs: |
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| 249 | self[key] = diffs[key] |
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| 250 | if getattr(self, 'result_column', None) is not None: |
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| 251 | setattr(self.result_column, key, diffs[key]) |
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| 252 | |
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| 253 | def column_types_eq(self, this, that): |
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| 254 | ret = isinstance(this, that.__class__) |
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| 255 | ret = ret or isinstance(that, this.__class__) |
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| 256 | # String length is a special case |
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| 257 | if ret and isinstance(that, sqlalchemy.types.String): |
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| 258 | ret = (getattr(this, 'length', None) == \ |
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| 259 | getattr(that, 'length', None)) |
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| 260 | return ret |
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| 261 | |
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| 262 | def accept_schema_visitor(self, visitor): |
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| 263 | return visitor.visit_column(self) |
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| 264 | |
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| 265 | |
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| 266 | class ChangesetTable(object): |
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| 267 | """Changeset extensions to SQLAlchemy tables.""" |
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| 268 | |
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| 269 | def create_column(self, column): |
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| 270 | """Creates a column. |
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| 271 | |
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| 272 | The column parameter may be a column definition or the name of |
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| 273 | a column in this table. |
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| 274 | """ |
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| 275 | if not isinstance(column, sqlalchemy.Column): |
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| 276 | # It's a column name |
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| 277 | column = getattr(self.c, str(column)) |
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| 278 | column.create(table=self) |
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| 279 | |
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| 280 | def drop_column(self, column): |
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| 281 | """Drop a column, given its name or definition.""" |
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| 282 | if not isinstance(column, sqlalchemy.Column): |
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| 283 | # It's a column name |
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| 284 | try: |
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| 285 | column = getattr(self.c, str(column), None) |
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| 286 | except AttributeError: |
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| 287 | # That column isn't part of the table. We don't need |
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| 288 | # its entire definition to drop the column, just its |
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| 289 | # name, so create a dummy column with the same name. |
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| 290 | column = sqlalchemy.Column(str(column)) |
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| 291 | column.drop(table=self) |
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| 292 | |
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| 293 | def _meta_key(self): |
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| 294 | return sqlalchemy.schema._get_table_key(self.name, self.schema) |
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| 295 | |
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| 296 | def deregister(self): |
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| 297 | """Remove this table from its metadata""" |
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| 298 | key = self._meta_key() |
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| 299 | meta = self.metadata |
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| 300 | if key in meta.tables: |
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| 301 | del meta.tables[key] |
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| 302 | |
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| 303 | def rename(self, name, *args, **kwargs): |
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| 304 | """Rename this table. |
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| 305 | |
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| 306 | This changes both the database name and the name of this |
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| 307 | Python object |
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| 308 | """ |
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| 309 | engine = self.bind |
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| 310 | visitorcallable = get_engine_visitor(engine, 'schemachanger') |
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| 311 | param = _WrapRename(self, name) |
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| 312 | _engine_run_visitor(engine, visitorcallable, param, *args, **kwargs) |
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| 313 | |
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| 314 | # Fix metadata registration |
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| 315 | meta = self.metadata |
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| 316 | self.deregister() |
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| 317 | self.name = name |
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| 318 | self._set_parent(meta) |
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| 319 | |
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| 320 | def _get_fullname(self): |
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| 321 | """Fullname should always be up to date""" |
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| 322 | # Copied from Table constructor |
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| 323 | if self.schema is not None: |
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| 324 | ret = "%s.%s"%(self.schema, self.name) |
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| 325 | else: |
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| 326 | ret = self.name |
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| 327 | return ret |
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| 328 | |
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| 329 | fullname = property(_get_fullname, (lambda self, val: None)) |
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| 330 | |
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| 331 | |
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| 332 | class ChangesetColumn(object): |
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| 333 | """Changeset extensions to SQLAlchemy columns""" |
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| 334 | |
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| 335 | def alter(self, *p, **k): |
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| 336 | """Alter a column's definition: ``ALTER TABLE ALTER COLUMN``. |
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| 337 | |
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| 338 | May supply a new column object, or a list of properties to |
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| 339 | change. |
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| 340 | |
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| 341 | For example; the following are equivalent: |
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| 342 | col.alter(Column('myint', Integer, nullable=False)) |
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| 343 | col.alter('myint', Integer, nullable=False) |
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| 344 | col.alter(name='myint', type=Integer, nullable=False) |
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| 345 | |
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| 346 | Column name, type, default, and nullable may be changed |
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| 347 | here. Note that for column defaults, only PassiveDefaults are |
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| 348 | managed by the database - changing others doesn't make sense. |
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| 349 | """ |
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| 350 | if 'table' not in k: |
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| 351 | k['table'] = self.table |
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| 352 | if 'engine' not in k: |
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| 353 | k['engine'] = k['table'].bind |
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| 354 | return alter_column(self, *p, **k) |
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| 355 | |
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| 356 | def create(self, table=None, *args, **kwargs): |
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| 357 | """Create this column in the database. |
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| 358 | |
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| 359 | Assumes the given table exists. ``ALTER TABLE ADD COLUMN``, |
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| 360 | for most databases. |
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| 361 | """ |
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| 362 | table = _normalize_table(self, table) |
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| 363 | engine = table.bind |
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| 364 | visitorcallable = get_engine_visitor(engine, 'columngenerator') |
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| 365 | engine._run_visitor(visitorcallable, self, *args, **kwargs) |
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| 366 | |
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| 367 | #add in foreign keys |
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| 368 | if self.foreign_keys: |
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| 369 | for fk in self.foreign_keys: |
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| 370 | visitorcallable = get_engine_visitor(engine, |
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| 371 | 'columnfkgenerator') |
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| 372 | engine._run_visitor(visitorcallable, self, fk=fk) |
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| 373 | return self |
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| 374 | |
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| 375 | def drop(self, table=None, *args, **kwargs): |
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| 376 | """Drop this column from the database, leaving its table intact. |
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| 377 | |
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| 378 | ``ALTER TABLE DROP COLUMN``, for most databases. |
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| 379 | """ |
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| 380 | table = _normalize_table(self, table) |
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| 381 | engine = table.bind |
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| 382 | visitorcallable = get_engine_visitor(engine, 'columndropper') |
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| 383 | engine._run_visitor(lambda dialect, conn: visitorcallable(conn), |
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| 384 | self, *args, **kwargs) |
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| 385 | return self |
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| 386 | |
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| 387 | |
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| 388 | class ChangesetIndex(object): |
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| 389 | """Changeset extensions to SQLAlchemy Indexes.""" |
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| 390 | |
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| 391 | def rename(self, name, *args, **kwargs): |
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| 392 | """Change the name of an index. |
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| 393 | |
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| 394 | This changes both the Python object name and the database |
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| 395 | name. |
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| 396 | """ |
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| 397 | engine = self.table.bind |
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| 398 | visitorcallable = get_engine_visitor(engine, 'schemachanger') |
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| 399 | param = _WrapRename(self, name) |
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| 400 | _engine_run_visitor(engine, visitorcallable, param, *args, **kwargs) |
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| 401 | self.name = name |
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| 402 | |
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| 403 | |
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| 404 | def _patch(): |
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| 405 | """All the 'ugly' operations that patch SQLAlchemy's internals.""" |
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| 406 | sqlalchemy.schema.Table.__bases__ += (ChangesetTable, ) |
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| 407 | sqlalchemy.schema.Column.__bases__ += (ChangesetColumn, ) |
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| 408 | sqlalchemy.schema.Index.__bases__ += (ChangesetIndex, ) |
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| 409 | _patch() |
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