Added LazyMap for django resolvers

graphene/contrib/django/fields.py

@@ -4,7 +4,7 @@ from graphene.core.fields import (
 from graphene import relay
 
 from graphene.core.fields import Field, LazyField
-from graphene.utils import cached_property, memoize
+from graphene.utils import cached_property, memoize, LazyMap
 
 from graphene.relay.types import BaseNode
 
@@ -22,17 +22,26 @@ def get_type_for_model(schema, model):
             return _type
 
 
-class DjangoConnectionField(relay.ConnectionField):
+def lazy_map(value, func):
+    if isinstance(value, Manager):
+        value = value.get_queryset()
+    if isinstance(value, QuerySet):
+        return LazyMap(value, func)
+    return value
 
+
+class DjangoConnectionField(relay.ConnectionField):
     def wrap_resolved(self, value, instance, args, info):
-        if isinstance(value, (QuerySet, Manager)):
-            cls = instance.__class__
-            value = [cls(s) for s in value.all()]
-        return value
+        return lazy_map(value, instance.__class__)
+
+
+class LazyListField(ListField):
+    def resolve(self, value, instance, args, info):
+        resolved = super(LazyListField, self).resolve(value, instance, args, info)
+        return lazy_map(resolved, instance.__class__)
 
 
 class ConnectionOrListField(LazyField):
-
     @memoize
     def get_field(self, schema):
         model_field = self.field_type
@@ -40,13 +49,12 @@ class ConnectionOrListField(LazyField):
         if field_object_type and issubclass(field_object_type, BaseNode):
             field = DjangoConnectionField(model_field)
         else:
-            field = ListField(model_field)
+            field = LazyListField(model_field)
         field.contribute_to_class(self.object_type, self.name)
         return field
 
 
 class DjangoModelField(Field):
-
     def __init__(self, model, *args, **kwargs):
         super(DjangoModelField, self).__init__(None, *args, **kwargs)
         self.model = model

graphene/core/types.py

@@ -101,6 +101,8 @@ class BaseObjectType(object):
             raise Exception("An interface cannot be initialized")
         if instance is None:
             return None
+        elif type(instance) is cls:
+            instance = instance.instance
         return super(BaseObjectType, cls).__new__(cls, instance, *args, **kwargs)
 
     def __init__(self, instance=None):
@@ -115,9 +117,12 @@ class BaseObjectType(object):
     def get_field(self, field):
         return getattr(self.instance, field, None)
 
+    def __eq__(self, other):
+        return self.instance.__eq__(other)
+
     def resolve(self, field_name, args, info):
         if field_name not in self._meta.fields_map.keys():
-            raise Exception('Field %s not found in model' % field_name)
+            raise Exception('Field %s not found in model %s' % (field_name, self._meta.type_name))
         custom_resolve_fn = 'resolve_%s' % field_name
         if hasattr(self, custom_resolve_fn):
             resolve_fn = getattr(self, custom_resolve_fn)

graphene/utils.py

@@ -41,3 +41,47 @@ def to_camel_case(snake_str):
     # We capitalize the first letter of each component except the first one
     # with the 'title' method and join them together.
     return components[0] + "".join(x.title() for x in components[1:])
+
+
+class LazyMap(object):
+    def __init__(self, origin, _map, state=None):
+        self._origin = origin
+        self._origin_iter = origin.__iter__()
+        self._state = state or []
+        self._finished = False
+        self._map = _map
+
+    def __iter__(self):
+        return self if not self._finished else iter(self._state)
+
+    def iter(self):
+        return self.__iter__()
+
+    def __len__(self):
+        return self._origin.__len__()
+
+    def __next__(self):
+        try:
+            n = next(self._origin_iter)
+            n = self._map(n)
+        except StopIteration as e:
+            self._finished = True
+            raise e
+        else:
+            self._state.append(n)
+            return n
+
+    def next(self):
+        return self.__next__()
+
+    def __getitem__(self, key):
+        item = self._origin.__getitem__(key)
+        if isinstance(key, slice):
+            return LazyMap(item, self._map)
+        return self._map(item)
+
+    def __getattr__(self, name):
+        return getattr(self._origin, name)
+
+    def __repr__(self):
+        return "<LazyMap %s>" % repr(self._origin)