- Fixed a bug within the custom operator plus :meth:`.TypeEngine.with_variant`

system, whereby using a :class:`.TypeDecorator` in conjunction with
variant would fail with an MRO error when a comparison operator was used.
fixes #3102

3 files changed, 46 insertions, 3 deletions

diff --git a/doc/build/changelog/changelog_08.rst b/doc/build/changelog/changelog_08.rst
index 187bc2138..4b036272b 100644
--- a/doc/build/changelog/changelog_08.rst
+++ b/doc/build/changelog/changelog_08.rst
@@ -12,6 +12,15 @@
     :version: 0.8.7
 
     .. change::
+        :tags: bug, sql
+        :versions: 1.0.0, 0.9.7
+        :tickets: 3102
+
+        Fixed a bug within the custom operator plus :meth:`.TypeEngine.with_variant`
+        system, whereby using a :class:`.TypeDecorator` in conjunction with
+        variant would fail with an MRO error when a comparison operator was used.
+
+    .. change::
         :tags: bug, mysql
         :versions: 1.0.0, 0.9.7
         :tickets: 3101
diff --git a/lib/sqlalchemy/sql/type_api.py b/lib/sqlalchemy/sql/type_api.py
index 48b447b37..444366bc0 100644
--- a/lib/sqlalchemy/sql/type_api.py
+++ b/lib/sqlalchemy/sql/type_api.py
@@ -631,8 +631,8 @@ class TypeDecorator(TypeEngine):
     @property
     def comparator_factory(self):
         return type("TDComparator",
-                    (TypeDecorator.Comparator, self.impl.comparator_factory),
-                    {})
+                (TypeDecorator.Comparator, self.impl.comparator_factory),
+                {})
 
     def _gen_dialect_impl(self, dialect):
         """
@@ -1026,6 +1026,11 @@ class Variant(TypeDecorator):
         mapping[dialect_name] = type_
         return Variant(self.impl, mapping)
 
+    @property
+    def comparator_factory(self):
+        """express comparison behavior in terms of the base type"""
+        return self.impl.comparator_factory
+
 def _reconstitute_comparator(expression):
     return expression.comparator
 
diff --git a/test/sql/test_operators.py b/test/sql/test_operators.py
index 1006dc33a..9b6b2297f 100644
--- a/test/sql/test_operators.py
+++ b/test/sql/test_operators.py
@@ -355,7 +355,7 @@ class TypeDecoratorComparatorTest(_CustomComparatorTests, fixtures.TestBase):
         class MyInteger(TypeDecorator):
             impl = Integer
 
-            class comparator_factory(TypeEngine.Comparator):
+            class comparator_factory(TypeDecorator.Comparator):
                 def __init__(self, expr):
                     self.expr = expr
 
@@ -368,6 +368,35 @@ class TypeDecoratorComparatorTest(_CustomComparatorTests, fixtures.TestBase):
 
         return MyInteger
 
+class TypeDecoratorWVariantComparatorTest(_CustomComparatorTests, fixtures.TestBase):
+    def _add_override_factory(self):
+
+        class SomeOtherInteger(Integer):
+            class comparator_factory(TypeEngine.Comparator):
+                def __init__(self, expr):
+                    self.expr = expr
+
+                def __add__(self, other):
+                    return self.expr.op("not goofy")(other)
+
+                def __and__(self, other):
+                    return self.expr.op("not goofy_and")(other)
+
+        class MyInteger(TypeDecorator):
+            impl = Integer
+
+            class comparator_factory(TypeDecorator.Comparator):
+                def __init__(self, expr):
+                    self.expr = expr
+
+                def __add__(self, other):
+                    return self.expr.op("goofy")(other)
+
+                def __and__(self, other):
+                    return self.expr.op("goofy_and")(other)
+
+        return MyInteger().with_variant(SomeOtherInteger, "mysql")
+
 
 class CustomEmbeddedinTypeDecoratorTest(_CustomComparatorTests, fixtures.TestBase):
     def _add_override_factory(self):