diff options
Diffstat (limited to 'lib/sqlalchemy/sql/schema.py')
| -rw-r--r-- | lib/sqlalchemy/sql/schema.py | 158 |
1 files changed, 115 insertions, 43 deletions
diff --git a/lib/sqlalchemy/sql/schema.py b/lib/sqlalchemy/sql/schema.py index a88203e84..25eb68f6f 100644 --- a/lib/sqlalchemy/sql/schema.py +++ b/lib/sqlalchemy/sql/schema.py @@ -572,18 +572,9 @@ class Table(DialectKWArgs, SchemaItem, TableClause): def _init_collections(self): pass - @util.memoized_property + @property def _autoincrement_column(self): - for col in self.primary_key: - if (col.autoincrement and col.type._type_affinity is not None and - issubclass(col.type._type_affinity, - type_api.INTEGERTYPE._type_affinity) and - (not col.foreign_keys or - col.autoincrement == 'ignore_fk') and - isinstance(col.default, (type(None), Sequence)) and - (col.server_default is None or - col.server_default.reflected)): - return col + return self.primary_key._autoincrement_column @property def key(self): @@ -913,17 +904,40 @@ class Column(SchemaItem, ColumnClause): argument is available such as ``server_default``, ``default`` and ``unique``. - :param autoincrement: This flag may be set to ``False`` to - indicate an integer primary key column that should not be - considered to be the "autoincrement" column, that is - the integer primary key column which generates values - implicitly upon INSERT and whose value is usually returned - via the DBAPI cursor.lastrowid attribute. It defaults - to ``True`` to satisfy the common use case of a table - with a single integer primary key column. If the table - has a composite primary key consisting of more than one - integer column, set this flag to True only on the - column that should be considered "autoincrement". + :param autoincrement: Set up "auto increment" semantics for an integer + primary key column. The default value is the string ``"auto"`` + which indicates that a single-column primary key that is of + an INTEGER type with no stated client-side or python-side defaults + should receive auto increment semantics automatically; + all other varieties of primary key columns will not. This + includes that :term:`DDL` such as Postgresql SERIAL or MySQL + AUTO_INCREMENT will be emitted for this column during a table + create, as well as that the column is assumed to generate new + integer primary key values when an INSERT statement invokes which + will be retrieved by the dialect. + + The flag may be set to ``True`` to indicate that a column which + is part of a composite (e.g. multi-column) primary key should + have autoincrement semantics, though note that only one column + within a primary key may have this setting. It can also + be set to ``True`` to indicate autoincrement semantics on a + column that has a client-side or server-side default configured, + however note that not all dialects can accommodate all styles + of default as an "autoincrement". It can also be + set to ``False`` on a single-column primary key that has a + datatype of INTEGER in order to disable auto increment semantics + for that column. + + .. versionchanged:: 1.1 The autoincrement flag now defaults to + ``"auto"`` which indicates autoincrement semantics by default + for single-column integer primary keys only; for composite + (multi-column) primary keys, autoincrement is never implicitly + enabled; as always, ``autoincrement=True`` will allow for + at most one of those columns to be an "autoincrement" column. + ``autoincrement=True`` may also be set on a :class:`.Column` + that has an explicit client-side or server-side default, + subject to limitations of the backend database and dialect. + The setting *only* has an effect for columns which are: @@ -940,11 +954,8 @@ class Column(SchemaItem, ColumnClause): primary_key=True, autoincrement='ignore_fk') It is typically not desirable to have "autoincrement" enabled - on such a column as its value intends to mirror that of a - primary key column elsewhere. - - * have no server side or client side defaults (with the exception - of Postgresql SERIAL). + on a column that refers to another via foreign key, as such a column + is required to refer to a value that originates from elsewhere. The setting has these two effects on columns that meet the above criteria: @@ -961,20 +972,15 @@ class Column(SchemaItem, ColumnClause): :ref:`sqlite_autoincrement` - * The column will be considered to be available as - cursor.lastrowid or equivalent, for those dialects which - "post fetch" newly inserted identifiers after a row has - been inserted (SQLite, MySQL, MS-SQL). It does not have - any effect in this regard for databases that use sequences - to generate primary key identifiers (i.e. Firebird, Postgresql, - Oracle). - - .. versionchanged:: 0.7.4 - ``autoincrement`` accepts a special value ``'ignore_fk'`` - to indicate that autoincrementing status regardless of foreign - key references. This applies to certain composite foreign key - setups, such as the one demonstrated in the ORM documentation - at :ref:`post_update`. + * The column will be considered to be available using an + "autoincrement" method specific to the backend database, such + as calling upon ``cursor.lastrowid``, using RETURNING in an + INSERT statement to get at a sequence-generated value, or using + special functions such as "SELECT scope_identity()". + These methods are highly specific to the DBAPIs and databases in + use and vary greatly, so care should be taken when associating + ``autoincrement=True`` with a custom default generation function. + :param default: A scalar, Python callable, or :class:`.ColumnElement` expression representing the @@ -1128,7 +1134,7 @@ class Column(SchemaItem, ColumnClause): self.system = kwargs.pop('system', False) self.doc = kwargs.pop('doc', None) self.onupdate = kwargs.pop('onupdate', None) - self.autoincrement = kwargs.pop('autoincrement', True) + self.autoincrement = kwargs.pop('autoincrement', "auto") self.constraints = set() self.foreign_keys = set() @@ -1263,12 +1269,12 @@ class Column(SchemaItem, ColumnClause): if self.primary_key: table.primary_key._replace(self) - Table._autoincrement_column._reset(table) elif self.key in table.primary_key: raise exc.ArgumentError( "Trying to redefine primary-key column '%s' as a " "non-primary-key column on table '%s'" % ( self.key, table.fullname)) + self.table = table if self.index: @@ -3026,11 +3032,77 @@ class PrimaryKeyConstraint(ColumnCollectionConstraint): self.columns.extend(columns) + PrimaryKeyConstraint._autoincrement_column._reset(self) self._set_parent_with_dispatch(self.table) def _replace(self, col): + PrimaryKeyConstraint._autoincrement_column._reset(self) self.columns.replace(col) + @property + def columns_autoinc_first(self): + autoinc = self._autoincrement_column + + if autoinc is not None: + return [autoinc] + [c for c in self.columns if c is not autoinc] + else: + return list(self.columns) + + @util.memoized_property + def _autoincrement_column(self): + + def _validate_autoinc(col, autoinc_true): + if col.type._type_affinity is None or not issubclass( + col.type._type_affinity, + type_api.INTEGERTYPE._type_affinity): + if autoinc_true: + raise exc.ArgumentError( + "Column type %s on column '%s' is not " + "compatible with autoincrement=True" % ( + col.type, + col + )) + else: + return False + elif not isinstance(col.default, (type(None), Sequence)) and \ + not autoinc_true: + return False + elif col.server_default is not None and not autoinc_true: + return False + elif ( + col.foreign_keys and col.autoincrement + not in (True, 'ignore_fk')): + return False + return True + + if len(self.columns) == 1: + col = list(self.columns)[0] + + if col.autoincrement is True: + _validate_autoinc(col, True) + return col + elif ( + col.autoincrement in ('auto', 'ignore_fk') and + _validate_autoinc(col, False) + ): + return col + + else: + autoinc = None + for col in self.columns: + if col.autoincrement is True: + _validate_autoinc(col, True) + if autoinc is not None: + raise exc.ArgumentError( + "Only one Column may be marked " + "autoincrement=True, found both %s and %s." % + (col.name, autoinc.name) + ) + else: + autoinc = col + + return autoinc + class UniqueConstraint(ColumnCollectionConstraint): """A table-level UNIQUE constraint. |