Support GQL interfaces for polymorphic SQLA models

Author: polgfred

graphene_sqlalchemy/__init__.py

@@ -1,11 +1,12 @@
 from .fields import SQLAlchemyConnectionField
-from .types import SQLAlchemyObjectType
+from .types import SQLAlchemyInterface, SQLAlchemyObjectType
 from .utils import get_query, get_session
 
 __version__ = "3.0.0b3"
 
 __all__ = [
     "__version__",
+    "SQLAlchemyInterface",
     "SQLAlchemyObjectType",
     "SQLAlchemyConnectionField",
     "get_query",

graphene_sqlalchemy/registry.py

@@ -18,15 +18,10 @@ def __init__(self):
         self._registry_unions = {}
 
     def register(self, obj_type):
+        from .types import SQLAlchemyBase
 
-        from .types import SQLAlchemyObjectType
-
-        if not isinstance(obj_type, type) or not issubclass(
-            obj_type, SQLAlchemyObjectType
-        ):
-            raise TypeError(
-                "Expected SQLAlchemyObjectType, but got: {!r}".format(obj_type)
-            )
+        if not isinstance(obj_type, type) or not issubclass(obj_type, SQLAlchemyBase):
+            raise TypeError("Expected SQLAlchemyBase, but got: {!r}".format(obj_type))
         assert obj_type._meta.registry == self, "Registry for a Model have to match."
         # assert self.get_type_for_model(cls._meta.model) in [None, cls], (
         #     'SQLAlchemy model "{}" already associated with '
@@ -38,14 +33,10 @@ def get_type_for_model(self, model):
         return self._registry.get(model)
 
     def register_orm_field(self, obj_type, field_name, orm_field):
-        from .types import SQLAlchemyObjectType
+        from .types import SQLAlchemyBase
 
-        if not isinstance(obj_type, type) or not issubclass(
-            obj_type, SQLAlchemyObjectType
-        ):
-            raise TypeError(
-                "Expected SQLAlchemyObjectType, but got: {!r}".format(obj_type)
-            )
+        if not isinstance(obj_type, type) or not issubclass(obj_type, SQLAlchemyBase):
+            raise TypeError("Expected SQLAlchemyBase, but got: {!r}".format(obj_type))
         if not field_name or not isinstance(field_name, str):
             raise TypeError("Expected a field name, but got: {!r}".format(field_name))
         self._registry_orm_fields[obj_type][field_name] = orm_field

graphene_sqlalchemy/tests/test_registry.py

@@ -28,7 +28,7 @@ def test_register_incorrect_object_type():
     class Spam:
         pass
 
-    re_err = "Expected SQLAlchemyObjectType, but got: .*Spam"
+    re_err = "Expected SQLAlchemyBase, but got: .*Spam"
     with pytest.raises(TypeError, match=re_err):
         reg.register(Spam)
 
@@ -51,7 +51,7 @@ def test_register_orm_field_incorrect_types():
     class Spam:
         pass
 
-    re_err = "Expected SQLAlchemyObjectType, but got: .*Spam"
+    re_err = "Expected SQLAlchemyBase, but got: .*Spam"
     with pytest.raises(TypeError, match=re_err):
         reg.register_orm_field(Spam, "name", Pet.name)
 

graphene_sqlalchemy/types.py

@@ -7,6 +7,8 @@
 
 from graphene import Field
 from graphene.relay import Connection, Node
+from graphene.types.base import BaseType
+from graphene.types.interface import Interface, InterfaceOptions
 from graphene.types.objecttype import ObjectType, ObjectTypeOptions
 from graphene.types.utils import yank_fields_from_attrs
 from graphene.utils.orderedtype import OrderedType
@@ -211,14 +213,7 @@ def construct_fields(
     return fields
 
 
-class SQLAlchemyObjectTypeOptions(ObjectTypeOptions):
-    model = None  # type: sqlalchemy.Model
-    registry = None  # type: sqlalchemy.Registry
-    connection = None  # type: sqlalchemy.Type[sqlalchemy.Connection]
-    id = None  # type: str
-
-
-class SQLAlchemyObjectType(ObjectType):
+class SQLAlchemyBase(BaseType):
     @classmethod
     def __init_subclass_with_meta__(
         cls,
@@ -237,6 +232,11 @@ def __init_subclass_with_meta__(
         _meta=None,
         **options
     ):
+        # We always want to bypass this hook unless we're defining a concrete
+        # `SQLAlchemyObjectType` or `SQLAlchemyInterface`.
+        if not _meta:
+            return
+
         # Make sure model is a valid SQLAlchemy model
         if not is_mapped_class(model):
             raise ValueError(
@@ -290,9 +290,6 @@ def __init_subclass_with_meta__(
                 "The connection must be a Connection. Received {}"
             ).format(connection.__name__)
 
-        if not _meta:
-            _meta = SQLAlchemyObjectTypeOptions(cls)
-
         _meta.model = model
         _meta.registry = registry
 
@@ -306,7 +303,7 @@ def __init_subclass_with_meta__(
 
         cls.connection = connection  # Public way to get the connection
 
-        super(SQLAlchemyObjectType, cls).__init_subclass_with_meta__(
+        super(SQLAlchemyBase, cls).__init_subclass_with_meta__(
             _meta=_meta, interfaces=interfaces, **options
         )
 
@@ -345,3 +342,39 @@ def enum_for_field(cls, field_name):
     sort_enum = classmethod(sort_enum_for_object_type)
 
     sort_argument = classmethod(sort_argument_for_object_type)
+
+
+class SQLAlchemyObjectTypeOptions(ObjectTypeOptions):
+    model = None  # type: sqlalchemy.Model
+    registry = None  # type: sqlalchemy.Registry
+    connection = None  # type: sqlalchemy.Type[sqlalchemy.Connection]
+    id = None  # type: str
+
+
+class SQLAlchemyObjectType(SQLAlchemyBase, ObjectType):
+    @classmethod
+    def __init_subclass_with_meta__(cls, _meta=None, **options):
+        if not _meta:
+            _meta = SQLAlchemyObjectTypeOptions(cls)
+
+        super(SQLAlchemyObjectType, cls).__init_subclass_with_meta__(
+            _meta=_meta, **options
+        )
+
+
+class SQLAlchemyInterfaceOptions(InterfaceOptions):
+    model = None  # type: sqlalchemy.Model
+    registry = None  # type: sqlalchemy.Registry
+    connection = None  # type: sqlalchemy.Type[sqlalchemy.Connection]
+    id = None  # type: str
+
+
+class SQLAlchemyInterface(SQLAlchemyBase, Interface):
+    @classmethod
+    def __init_subclass_with_meta__(cls, _meta=None, **options):
+        if not _meta:
+            _meta = SQLAlchemyInterfaceOptions(cls)
+
+        super(SQLAlchemyInterface, cls).__init_subclass_with_meta__(
+            _meta=_meta, **options
+        )