schematype support for typedecorator / PG ENUM

[Mike Bayer]

figure out how users would know to follow this pattern, or how this can be transparent:

import sqlalchemy as sa
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.dialects import postgresql


Base = declarative_base()

class MyEnum(sa.types.TypeDecorator, sa.types.SchemaType):
    impl = postgresql.ENUM

    def _set_parent(self, column):
        self.impl._set_parent(column)

class Test(Base):
    __tablename__ = 'test'

    id = sa.Column(sa.Integer, primary_key=True)
    enum_column = sa.Column(MyEnum('1', '2', '3', name='my_enum_type'))

engine = sa.create_engine('postgresql://scott:tiger@localhost/test', echo=True)
Base.metadata.create_all(engine)

[Mike Bayer]

diff --git a/lib/sqlalchemy/sql/type_api.py b/lib/sqlalchemy/sql/type_api.py
index b9826e5..9bfd6dc 100644
--- a/lib/sqlalchemy/sql/type_api.py
+++ b/lib/sqlalchemy/sql/type_api.py
@@ -772,6 +772,11 @@ class TypeDecorator(TypeEngine):
         """
         return self.impl._type_affinity

+    def _set_parent(self, column):
+        """Support SchemaType"""
+
+        self.impl._set_parent(column)
+
     def type_engine(self, dialect):
         """Return a dialect-specific :class:`.TypeEngine` instance
         for this :class:`.TypeDecorator`.

[Mike Bayer]

• The :class:.TypeDecorator type extender will now work in conjunction with a :class:.SchemaType implementation, typically :class:.Enum or :class:.Boolean with regards to ensuring that the per-table events are propagated from the implementation type to the outer type. These events are used to ensure that the constraints or Postgresql types (e.g. ENUM) are correctly created (and possibly dropped) along with the parent table. fixes #2919

→ <<cset ed535649d423>>

[Mike Bayer]

• fix missing argument in TypeDecorator.copy(), fixes #3584, references #2919

→ <<cset 37565d2ce2b4>>