Add values_callable feature to Enum

Added support for :class:`.Enum` to persist the values of the enumeration,
rather than the keys, when using a Python pep-435 style enumerated object.
The user supplies a callable function that will return the string values to
be persisted.  This allows enumerations against non-string values to be
value-persistable as well.  Pull request courtesy Jon Snyder.

Pull-request: https://github.com/zzzeek/sqlalchemy/pull/410
Fixes: #3906
Change-Id: Id385465d215d1e5baaad68368b168afdd846b82c

1 files changed, 51 insertions, 1 deletions

diff --git a/test/sql/test_types.py b/test/sql/test_types.py
index fa917c466..002094f7b 100644
--- a/test/sql/test_types.py
+++ b/test/sql/test_types.py
@@ -1170,9 +1170,24 @@ class EnumTest(AssertsCompiledSQL, fixtures.TablesTest):
                 self.__members__[alias] = self
                 setattr(self.__class__, alias, self)
 
+    class SomeOtherEnum(SomeEnum):
+        __members__ = OrderedDict()
+
     one = SomeEnum('one', 1)
     two = SomeEnum('two', 2)
     three = SomeEnum('three', 3, 'four')
+    a_member = SomeEnum('AMember', 'a')
+    b_member = SomeEnum('BMember', 'b')
+
+    other_one = SomeOtherEnum('one', 1)
+    other_two = SomeOtherEnum('two', 2)
+    other_three = SomeOtherEnum('three', 3)
+    other_a_member = SomeOtherEnum('AMember', 'a')
+    other_b_member = SomeOtherEnum('BMember', 'b')
+
+    @staticmethod
+    def get_enum_string_values(some_enum):
+        return [str(v.value) for v in some_enum.__members__.values()]
 
     @classmethod
     def define_tables(cls, metadata):
@@ -1197,6 +1212,14 @@ class EnumTest(AssertsCompiledSQL, fixtures.TablesTest):
             Column('someenum', Enum(cls.SomeEnum))
         )
 
+        Table(
+            'stdlib_enum_table2', metadata,
+            Column("id", Integer, primary_key=True),
+            Column('someotherenum',
+                   Enum(cls.SomeOtherEnum,
+                        values_callable=EnumTest.get_enum_string_values))
+        )
+
     def test_python_type(self):
         eq_(types.Enum(self.SomeEnum).python_type, self.SomeEnum)
 
@@ -1521,6 +1544,27 @@ class EnumTest(AssertsCompiledSQL, fixtures.TablesTest):
             ]
         )
 
+    def test_pep435_enum_values_callable_round_trip(self):
+        stdlib_enum_table_custom_values =\
+            self.tables['stdlib_enum_table2']
+
+        stdlib_enum_table_custom_values.insert().execute([
+            {'id': 1, 'someotherenum': self.SomeOtherEnum.AMember},
+            {'id': 2, 'someotherenum': self.SomeOtherEnum.BMember},
+            {'id': 3, 'someotherenum': self.SomeOtherEnum.AMember}
+        ])
+
+        eq_(
+            stdlib_enum_table_custom_values.select().
+            order_by(stdlib_enum_table_custom_values.c.id).execute().
+            fetchall(),
+            [
+                (1, self.SomeOtherEnum.AMember),
+                (2, self.SomeOtherEnum.BMember),
+                (3, self.SomeOtherEnum.AMember)
+            ]
+        )
+
     def test_adapt(self):
         from sqlalchemy.dialects.postgresql import ENUM
         e1 = Enum('one', 'two', 'three', native_enum=False)
@@ -1544,7 +1588,13 @@ class EnumTest(AssertsCompiledSQL, fixtures.TablesTest):
         is_(e1.adapt(Enum).metadata, e1.metadata)
         e1 = Enum(self.SomeEnum)
         eq_(e1.adapt(ENUM).name, 'someenum')
-        eq_(e1.adapt(ENUM).enums, ['one', 'two', 'three', 'four'])
+        eq_(e1.adapt(ENUM).enums,
+            ['one', 'two', 'three', 'four', 'AMember', 'BMember'])
+
+        e1_vc = Enum(self.SomeOtherEnum,
+                     values_callable=EnumTest.get_enum_string_values)
+        eq_(e1_vc.adapt(ENUM).name, 'someotherenum')
+        eq_(e1_vc.adapt(ENUM).enums, ['1', '2', '3', 'a', 'b'])
 
     @testing.provide_metadata
     def test_create_metadata_bound_no_crash(self):