diff options
Diffstat (limited to 'lib/sqlalchemy/schema.py')
| -rw-r--r-- | lib/sqlalchemy/schema.py | 49 |
1 files changed, 26 insertions, 23 deletions
diff --git a/lib/sqlalchemy/schema.py b/lib/sqlalchemy/schema.py index aeb7d61af..c96d8adf4 100644 --- a/lib/sqlalchemy/schema.py +++ b/lib/sqlalchemy/schema.py @@ -749,51 +749,51 @@ class Column(SchemaItem, expression.ColumnClause): class ForeignKey(SchemaItem): """Defines a column-level FOREIGN KEY constraint between two columns. - ``ForeignKey`` is specified as an argument to a ``Column`` object. + ``ForeignKey`` is specified as an argument to a :class:`Column` object, e.g.:: + + t = Table("remote_table", metadata, + Column("remote_id", ForeignKey("main_table.id")) + ) - For a composite (multiple column) FOREIGN KEY, use a ForeignKeyConstraint - within the Table definition. + For a composite (multiple column) FOREIGN KEY, use a :class:`ForeignKeyConstraint` + object specified at the level of the :class:`Table`. + + Further examples of foreign key configuration are in :ref:`metadata_foreignkeys`. """ def __init__(self, column, constraint=None, use_alter=False, name=None, onupdate=None, ondelete=None, deferrable=None, initially=None): - """Construct a column-level FOREIGN KEY. + """ + Construct a column-level FOREIGN KEY. - column - A single target column for the key relationship. A ``Column`` + :param column: A single target column for the key relationship. A :class:`Column` object or a column name as a string: ``tablename.columnname`` or ``schema.tablename.columnname``. - constraint - Optional. A parent ``ForeignKeyConstraint`` object. If not - supplied, a ``ForeignKeyConstraint`` will be automatically created + :param constraint: Optional. A parent :class:`ForeignKeyConstraint` object. If not + supplied, a :class:`ForeignKeyConstraint` will be automatically created and added to the parent table. - name - Optional string. An in-database name for the key if `constraint` is + :param name: Optional string. An in-database name for the key if `constraint` is not provided. - onupdate - Optional string. If set, emit ON UPDATE <value> when issuing DDL + :param onupdate: Optional string. If set, emit ON UPDATE <value> when issuing DDL for this constraint. Typical values include CASCADE, DELETE and RESTRICT. - ondelete - Optional string. If set, emit ON DELETE <value> when issuing DDL + :param ondelete: Optional string. If set, emit ON DELETE <value> when issuing DDL for this constraint. Typical values include CASCADE, DELETE and RESTRICT. - deferrable - Optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when + :param deferrable: Optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when issuing DDL for this constraint. - initially - Optional string. If set, emit INITIALLY <value> when issuing DDL + :param initially: Optional string. If set, emit INITIALLY <value> when issuing DDL for this constraint. - use_alter - If True, do not emit this key as part of the CREATE TABLE + :param use_alter: If True, do not emit this key as part of the CREATE TABLE definition. Instead, use ALTER TABLE after table creation to add the key. Useful for circular dependencies. + """ self._colspec = column @@ -1169,8 +1169,11 @@ class ForeignKeyConstraint(Constraint): Defines a single column or composite FOREIGN KEY ... REFERENCES constraint. For a no-frills, single column foreign key, adding a - ``ForeignKey`` to the definition of a ``Column`` is a shorthand equivalent - for an unnamed, single column ``ForeignKeyConstraint``. + :class:`ForeignKey` to the definition of a :class:`Column` is a shorthand equivalent + for an unnamed, single column :class:`ForeignKeyConstraint`. + + Examples of foreign key configuration are in :ref:`metadata_foreignkeys`. + """ def __init__(self, columns, refcolumns, name=None, onupdate=None, ondelete=None, use_alter=False, deferrable=None, initially=None): |