Removed Meta inheritance in favor of __init_subclass_with_meta__

Author: syrusakbary

graphene_django/types.py

@@ -3,103 +3,93 @@
 import six
 
 from django.utils.functional import SimpleLazyObject
-from graphene import Field, ObjectType
-from graphene.types.objecttype import ObjectTypeMeta
-from graphene.types.options import Options
-from graphene.types.utils import merge, yank_fields_from_attrs
-from graphene.utils.is_base_type import is_base_type
+from graphene import Field
+from graphene.relay import Connection, Node
+from graphene.types.objecttype import ObjectType, ObjectTypeOptions
+from graphene.types.utils import yank_fields_from_attrs
 
 from .converter import convert_django_field_with_choices
 from .registry import Registry, get_global_registry
 from .utils import (DJANGO_FILTER_INSTALLED, get_model_fields,
                     is_valid_django_model)
 
 
-def construct_fields(options):
-    _model_fields = get_model_fields(options.model)
-    only_fields = options.only_fields
-    exclude_fields = options.exclude_fields
+def construct_fields(model, registry, only_fields, exclude_fields):
+    _model_fields = get_model_fields(model)
 
     fields = OrderedDict()
     for name, field in _model_fields:
-        is_not_in_only = only_fields and name not in options.only_fields
-        is_already_created = name in options.fields
-        is_excluded = name in exclude_fields or is_already_created
+        is_not_in_only = only_fields and name not in only_fields
+        # is_already_created = name in options.fields
+        is_excluded = name in exclude_fields # or is_already_created
         # https://docs.djangoproject.com/en/1.10/ref/models/fields/#django.db.models.ForeignKey.related_query_name
         is_no_backref = str(name).endswith('+')
         if is_not_in_only or is_excluded or is_no_backref:
             # We skip this field if we specify only_fields and is not
             # in there. Or when we exclude this field in exclude_fields.
             # Or when there is no back reference.
             continue
-        converted = convert_django_field_with_choices(field, options.registry)
+        converted = convert_django_field_with_choices(field, registry)
         fields[name] = converted
 
     return fields
 
 
-class DjangoObjectTypeMeta(ObjectTypeMeta):
-
-    @staticmethod
-    def __new__(cls, name, bases, attrs):
-        # Also ensure initialization is only performed for subclasses of
-        # DjangoObjectType
-        if not is_base_type(bases, DjangoObjectTypeMeta):
-            return type.__new__(cls, name, bases, attrs)
-
-        defaults = dict(
-            name=name,
-            description=attrs.pop('__doc__', None),
-            model=None,
-            local_fields=None,
-            only_fields=(),
-            exclude_fields=(),
-            interfaces=(),
-            skip_registry=False,
-            registry=None
-        )
-        if DJANGO_FILTER_INSTALLED:
-            # In case Django filter is available, then
-            # we allow more attributes in Meta
-            defaults.update(
-                filter_fields=(),
-            )
-
-        options = Options(
-            attrs.pop('Meta', None),
-            **defaults
-        )
-        if not options.registry:
-            options.registry = get_global_registry()
-        assert isinstance(options.registry, Registry), (
-            'The attribute registry in {}.Meta needs to be an instance of '
-            'Registry, received "{}".'
-        ).format(name, options.registry)
-        assert is_valid_django_model(options.model), (
+class DjangoObjectTypeOptions(ObjectTypeOptions):
+    model = None  # type: Model
+    registry = None  # type: Registry
+    connection = None  # type: Type[Connection]
+
+    filter_fields = ()
+
+
+class DjangoObjectType(ObjectType):
+    @classmethod
+    def __init_subclass_with_meta__(cls, model=None, registry=None, skip_registry=False,
+        only_fields=(), exclude_fields=(), filter_fields=None, connection=None, use_connection=None, interfaces=(), **options):
+        assert is_valid_django_model(model), (
             'You need to pass a valid Django Model in {}.Meta, received "{}".'
-        ).format(name, options.model)
+        ).format(cls.__name__, model)
+
+        if not registry:
+            registry = get_global_registry()
 
-        cls = ObjectTypeMeta.__new__(cls, name, bases, dict(attrs, _meta=options))
+        assert isinstance(registry, Registry), (
+            'The attribute registry in {} needs to be an instance of '
+            'Registry, received "{}".'
+        ).format(cls.__name__, registry)
 
-        options.registry.register(cls)
+        if not DJANGO_FILTER_INSTALLED and filter_fields:
+            raise Exception("Can only set filter_fields if Django-Filter is installed")
 
-        options.django_fields = yank_fields_from_attrs(
-            construct_fields(options),
+        django_fields = yank_fields_from_attrs(
+            construct_fields(model, registry, only_fields, exclude_fields),
             _as=Field,
         )
-        options.fields = merge(
-            options.interface_fields,
-            options.django_fields,
-            options.base_fields,
-            options.local_fields
-        )
 
-        return cls
+        if use_connection is None and interfaces:
+            use_connection = any((issubclass(interface, Node) for interface in interfaces))
+
+        if use_connection and not connection:
+            # We create the connection automatically
+            connection = Connection.create_type('{}Connection'.format(cls.__name__), node=cls)
+
+        if connection is not None:
+            assert issubclass(connection, Connection), "The connection must be a Connection. Received {}".format(connection.__name__)
 
+        _meta = DjangoObjectTypeOptions(cls)
+        _meta.model = model
+        _meta.registry = registry
+        _meta.filter_fields = filter_fields
+        _meta.fields = django_fields
+        _meta.connection = connection
 
-class DjangoObjectType(six.with_metaclass(DjangoObjectTypeMeta, ObjectType)):
+        super(DjangoObjectType, cls).__init_subclass_with_meta__(_meta=_meta, interfaces=interfaces, **options)
+            
+        if not skip_registry:
+            registry.register(cls)
 
-    def resolve_id(self, args, context, info):
+    def resolve_id(self):
         return self.pk
 
     @classmethod