Add ``omit_aliases`` in ``Enum``.

Introduce a new parameter :paramref:`_types.Enum.omit_aliases` in
:class:`_types.Enum` type allow filtering aliases when using a pep435 Enum.
Previous versions of SQLAlchemy kept aliases in all cases, creating
database enum type with additional states, meaning that they were treated
as different values in the db. For backward compatibility this flag
defaults to ``False`` in the 1.4 series, but will be switched to ``True``
in a future version. A deprecation warning is raise if this flag is not
specified and the passed enum contains aliases.

Fixes: #6146
Change-Id: I547322ffa90d0273d91bb3bf8bfea6ec934d48b9

1 files changed, 29 insertions, 1 deletions

diff --git a/lib/sqlalchemy/sql/sqltypes.py b/lib/sqlalchemy/sql/sqltypes.py
index 367b2e203..59ba7c391 100644
--- a/lib/sqlalchemy/sql/sqltypes.py
+++ b/lib/sqlalchemy/sql/sqltypes.py
@@ -41,6 +41,7 @@ from .. import processors
 from .. import util
 from ..util import compat
 from ..util import langhelpers
+from ..util import OrderedDict
 from ..util import pickle
 
 
@@ -1425,7 +1426,15 @@ class Enum(Emulated, String, SchemaType):
 
            .. versionadded:: 1.3.8
 
+        :param omit_aliases: A boolean that when true will remove aliases from
+           pep 435 enums. For backward compatibility it defaults to ``False``.
+           A deprecation warning is raised if the enum has aliases and this
+           flag was not set.
 
+           .. versionadded:: 1.4.4
+
+           .. deprecated:: 1.4  The default will be changed to ``True`` in
+              SQLAlchemy 2.0.
 
         """
         self._enum_init(enums, kw)
@@ -1450,6 +1459,7 @@ class Enum(Emulated, String, SchemaType):
         self.values_callable = kw.pop("values_callable", None)
         self._sort_key_function = kw.pop("sort_key_function", NO_ARG)
         length_arg = kw.pop("length", NO_ARG)
+        self._omit_aliases = kw.pop("omit_aliases", NO_ARG)
 
         values, objects = self._parse_into_values(enums, kw)
         self._setup_for_values(values, objects, kw)
@@ -1506,7 +1516,24 @@ class Enum(Emulated, String, SchemaType):
 
         if len(enums) == 1 and hasattr(enums[0], "__members__"):
             self.enum_class = enums[0]
-            members = self.enum_class.__members__
+
+            _members = self.enum_class.__members__
+
+            aliases = [n for n, v in _members.items() if v.name != n]
+            if self._omit_aliases is NO_ARG and aliases:
+                util.warn_deprecated_20(
+                    "The provided enum %s contains the aliases %s. The "
+                    "``omit_aliases`` will default to ``True`` in SQLAlchemy "
+                    "2.0. Specify a value to silence this warning."
+                    % (self.enum_class.__name__, aliases)
+                )
+            if self._omit_aliases is True:
+                # remove aliases
+                members = OrderedDict(
+                    (n, v) for n, v in _members.items() if v.name == n
+                )
+            else:
+                members = _members
             if self.values_callable:
                 values = self.values_callable(self.enum_class)
             else:
@@ -1633,6 +1660,7 @@ class Enum(Emulated, String, SchemaType):
         kw.setdefault("values_callable", self.values_callable)
         kw.setdefault("create_constraint", self.create_constraint)
         kw.setdefault("length", self.length)
+        kw.setdefault("omit_aliases", self._omit_aliases)
         assert "_enums" in kw
         return impltype(**kw)