Add a type to retrieve single nodes with optimizations made

.gitignore

@@ -10,3 +10,4 @@ dist/
 build/
 .coverage
 htmlcov/
+.*/

graphene_django_optimizer/types.py

+from graphene_django.types import DjangoObjectType
+from .query import query
+
+
+class OptimizedDjangoObjectType(DjangoObjectType):
+    class Meta:
+        abstract = True
+
+    @classmethod
+    def optimize_node(cls, info, qs, pk):
+        try:
+            return query(qs, info).get(pk=pk)
+        except cls._meta.model.DoesNotExist:
+            return None
+
+    @classmethod
+    def get_node(cls, info, id):
+        return cls.optimize_node(info, cls._meta.model.objects, id)