The Enum's `name` property is lost within an autogenerated migration

[mberdyshev]

Describe the bug A migration doesn't provide the name property of Enum if sqlalchemy.Enum is augmented with sqlalchemy.types.Decorator. Even if the name property is explicitly given.

Expected behavior The property has to be provided in Enum's definition inside a migration.

To Reproduce sql_types.py

from typing import Any
from sqlalchemy import Enum, TypeDecorator

class Enum1(Enum):
    def __init__(self, *enums: object, **kw: Any):
        validate_strings = kw.pop("validate_strings", True)
        super().__init__(*enums, **kw, validate_strings=validate_strings)

class Enum2(TypeDecorator):
    impl = Enum
    cache_ok = True

    def __init__(self, *enums: object, **kw: Any):
        validate_strings = kw.pop("validate_strings", True)
        super().__init__(*enums, **kw, validate_strings=validate_strings)

tables.py

import enum
from sqlalchemy import Column, MetaData, Table
from sql_types import Enum1, Enum2

class TestEnum(str, enum.Enum):
    FIRST = enum.auto()
    SECOND = enum.auto()

metadata = MetaData()

test_table = Table(
    "test",
    metadata,
    Column("col1", Enum1(TestEnum), nullable=False),
    Column("col2", Enum2(TestEnum, name="enum2"), nullable=False),
)

alembic revision --autogenerate -m "Enums" provides (shortened):

def upgrade() -> None:
    # ### commands auto generated by Alembic - please adjust! ###
    op.create_table('test',
    sa.Column('col1', db.sql_types.Enum1('FIRST', 'SECOND', name='testenum'), nullable=False),
    sa.Column('col2', db.sql_types.Enum2('FIRST', 'SECOND'), nullable=False)
    )
    # ### end Alembic commands ###

def downgrade() -> None:
    # ### commands auto generated by Alembic - please adjust! ###
    op.drop_table('test')
    # ### end Alembic commands ###

Error As you can see from the migration enums are defined differently - the second one misses its name property. If I try to run it on PostgreSQL I get the error:

Stacktrace

INFO  [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO  [alembic.runtime.migration] Generating static SQL
INFO  [alembic.runtime.migration] Will assume transactional DDL.
BEGIN;

CREATE TABLE alembic_version (
    version_num VARCHAR(32) NOT NULL,
    CONSTRAINT alembic_version_pkc PRIMARY KEY (version_num)
);

INFO  [alembic.runtime.migration] Running upgrade  -> 264b6f57ae76, Enums
-- Running upgrade  -> 264b6f57ae76

CREATE TYPE testenum AS ENUM ('FIRST', 'SECOND');

Traceback (most recent call last):
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.10_3.10.3056.0_x64__qbz5n2kfra8p0\lib\runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.10_3.10.3056.0_x64__qbz5n2kfra8p0\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\__main__.py", line 4, in <module>
    main(prog="alembic")
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\config.py", line 636, in main
    CommandLine(prog=prog).main(argv=argv)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\config.py", line 626, in main
    self.run_cmd(cfg, options)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\config.py", line 603, in run_cmd
    fn(
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\command.py", line 406, in upgrade
    script.run_env()
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\script\base.py", line 586, in run_env
    util.load_python_file(self.dir, "env.py")
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\util\pyfiles.py", line 95, in load_python_file
    module = load_module_py(module_id, path)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\util\pyfiles.py", line 113, in load_module_py
    spec.loader.exec_module(module)  # type: ignore
  File "<frozen importlib._bootstrap_external>", line 883, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "c:\Users\Михаил\PycharmProjects\Example Project\db\alembic\env.py", line 78, in <module>
    run_migrations_offline()
  File "c:\Users\Михаил\PycharmProjects\Example Project\db\alembic\env.py", line 52, in run_migrations_offline
    context.run_migrations()
  File "<string>", line 8, in run_migrations
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\runtime\environment.py", line 946, in run_migrations
    self.get_context().run_migrations(**kw)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\runtime\migration.py", line 628, in run_migrations
    step.migration_fn(**kw)
  File "C:\Users\Михаил\PycharmProjects\Example Project\db\alembic\versions\264b6f57ae76_enums.py", line 24, in upgrade
    op.create_table('test',
  File "<string>", line 8, in create_table
  File "<string>", line 3, in create_table
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\operations\ops.py", line 1318, in create_table
    return operations.invoke(op)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\operations\base.py", line 442, in invoke
    return fn(self, operation)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\operations\toimpl.py", line 143, in create_table
    operations.impl.create_table(table, **kw)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\ddl\impl.py", line 366, in create_table
    table.dispatch.before_create(
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\event\attr.py", line 497, in __call__
    fn(*args, **kw)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\util\langhelpers.py", line 852, in __call__
    return getattr(self.target, self.name)(*arg, **kw)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\sql\sqltypes.py", line 1130, in _on_table_create
    t._on_table_create(target, bind, **kw)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\dialects\postgresql\named_types.py", line 98, in _on_table_create
    self.create(bind=bind, checkfirst=checkfirst)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\dialects\postgresql\named_types.py", line 338, in create
    super().create(bind, checkfirst=checkfirst)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\dialects\postgresql\named_types.py", line 51, in create
    bind._run_ddl_visitor(self.DDLGenerator, self, checkfirst=checkfirst)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\engine\mock.py", line 61, in _run_ddl_visitor
    visitorcallable(self.dialect, self, **kwargs).traverse_single(element)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\sql\visitors.py", line 664, in traverse_single
    return meth(obj, **kw)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\dialects\postgresql\named_types.py", line 153, in visit_enum
    self.connection.execute(CreateEnumType(enum))
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\engine\mock.py", line 69, in execute
    return self._execute_impl(obj, parameters)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\runtime\migration.py", line 675, in dump
    self.impl._exec(construct)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\alembic\ddl\impl.py", line 190, in _exec
    compiled = construct.compile(dialect=self.dialect, **compile_kw)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\sql\elements.py", line 308, in compile
    return self._compiler(dialect, **kw)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\sql\ddl.py", line 69, in _compiler
    return dialect.ddl_compiler(dialect, self, **kw)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\sql\compiler.py", line 870, in __init__
    self.string = self.process(self.statement, **compile_kwargs)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\sql\compiler.py", line 915, in process
    return obj._compiler_dispatch(self, **kwargs)
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\sql\visitors.py", line 141, in _compiler_dispatch
    return meth(self, **kw)  # type: ignore  # noqa: E501
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\dialects\postgresql\base.py", line 2236, in visit_create_enum_type
    self.preparer.format_type(type_),
  File "C:\Users\Михаил\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\sqlalchemy\dialects\postgresql\base.py", line 2728, in format_type
    raise exc.CompileError(
sqlalchemy.exc.CompileError: PostgreSQL ENUM type requires a name.

Versions.

• OS: Windows 11 23H2
• Python: 3.10.11
• Alembic: 1.13.3
• SQLAlchemy: 2.0.35
• Database: PostgreSQL 17.0.1
• DBAPI: psycopg2 2.9.9

Additional context The docs state that subclassing from TypeDecorator should be preferred:

This method is preferred to direct subclassing of SQLAlchemy’s built-in types as it ensures that all required functionality of the underlying type is kept in place.

Have a nice day!