Fixed #36383 -- Improved migration serialization for functools.partial objects.

Author: adamchainz

django/db/migrations/serializer.py

@@ -207,23 +207,11 @@ def serialize(self):
 
 class FunctoolsPartialSerializer(BaseSerializer):
     def serialize(self):
-        # Serialize functools.partial() arguments
-        func_string, func_imports = serializer_factory(self.value.func).serialize()
-        args_string, args_imports = serializer_factory(self.value.args).serialize()
-        keywords_string, keywords_imports = serializer_factory(
-            self.value.keywords
-        ).serialize()
-        # Add any imports needed by arguments
-        imports = {"import functools", *func_imports, *args_imports, *keywords_imports}
-        return (
-            "functools.%s(%s, *%s, **%s)"
-            % (
-                self.value.__class__.__name__,
-                func_string,
-                args_string,
-                keywords_string,
-            ),
-            imports,
+        partial_name = self.value.__class__.__name__
+        return DeconstructibleSerializer.serialize_deconstructed(
+            f"functools.{partial_name}",
+            (self.value.func, *self.value.args),
+            self.value.keywords,
         )
 
 

tests/migrations/test_writer.py

@@ -911,7 +911,7 @@ def test_serialize_functools_partial(self):
         string, imports = MigrationWriter.serialize(value)
         self.assertSerializedFunctoolsPartialEqual(
             value,
-            "functools.partial(datetime.timedelta, *(), **{})",
+            "functools.partial(datetime.timedelta)",
             {"import datetime", "import functools"},
         )
 
@@ -920,7 +920,7 @@ def test_serialize_functools_partial_posarg(self):
         string, imports = MigrationWriter.serialize(value)
         self.assertSerializedFunctoolsPartialEqual(
             value,
-            "functools.partial(datetime.timedelta, *(1,), **{})",
+            "functools.partial(datetime.timedelta, 1)",
             {"import datetime", "import functools"},
         )
 
@@ -929,7 +929,7 @@ def test_serialize_functools_partial_kwarg(self):
         string, imports = MigrationWriter.serialize(value)
         self.assertSerializedFunctoolsPartialEqual(
             value,
-            "functools.partial(datetime.timedelta, *(), **{'seconds': 2})",
+            "functools.partial(datetime.timedelta, seconds=2)",
             {"import datetime", "import functools"},
         )
 
@@ -938,7 +938,7 @@ def test_serialize_functools_partial_mixed(self):
         string, imports = MigrationWriter.serialize(value)
         self.assertSerializedFunctoolsPartialEqual(
             value,
-            "functools.partial(datetime.timedelta, *(1,), **{'seconds': 2})",
+            "functools.partial(datetime.timedelta, 1, seconds=2)",
             {"import datetime", "import functools"},
         )
 
@@ -947,7 +947,7 @@ def test_serialize_functools_partial_non_identifier_keyword(self):
         string, imports = MigrationWriter.serialize(value)
         self.assertSerializedFunctoolsPartialEqual(
             value,
-            "functools.partial(datetime.timedelta, *(), **{'kebab-case': 1})",
+            "functools.partial(datetime.timedelta, **{'kebab-case': 1})",
             {"import datetime", "import functools"},
         )
 
@@ -956,7 +956,7 @@ def test_serialize_functools_partialmethod(self):
         string, imports = MigrationWriter.serialize(value)
         result = self.assertSerializedFunctoolsPartialEqual(
             value,
-            "functools.partialmethod(datetime.timedelta, *(1,), **{'seconds': 2})",
+            "functools.partialmethod(datetime.timedelta, 1, seconds=2)",
             {"import datetime", "import functools"},
         )
         self.assertIsInstance(result, functools.partialmethod)