Improved Mutation docs. Fixed #402

Author: syrusakbary

docs/types/mutations.rst

@@ -10,19 +10,20 @@ This example defines a Mutation:
 
 .. code:: python
 
-    import graphene
+import graphene
 
-    class CreatePerson(graphene.Mutation):
-        class Input:
-            name = graphene.String()
+class CreatePerson(graphene.Mutation):
+    class Input:
+        name = graphene.String()
 
-        ok = graphene.Boolean()
-        person = graphene.Field(lambda: Person)
+    ok = graphene.Boolean()
+    person = graphene.Field(lambda: Person)
 
-        def mutate(self, args, context, info):
-            person = Person(name=args.get('name'))
-            ok = True
-            return CreatePerson(person=person, ok=ok)
+    @staticmethod
+    def mutate(root, args, context, info):
+        person = Person(name=args.get('name'))
+        ok = True
+        return CreatePerson(person=person, ok=ok)
 
 **person** and **ok** are the output fields of the Mutation when is
 resolved.
@@ -42,11 +43,16 @@ So, we can finish our schema like this:
 
     class Person(graphene.ObjectType):
         name = graphene.String()
+        age = graphene.Int()
 
     class MyMutations(graphene.ObjectType):
         create_person = CreatePerson.Field()
 
-    schema = graphene.Schema(mutation=MyMutations)
+    # We must define a query for our schema
+    class Query(graphene.ObjectType):
+        person = graphene.Field(Person)
+
+    schema = graphene.Schema(query=Query, mutation=MyMutations)
 
 Executing the Mutation
 ----------------------
@@ -96,11 +102,12 @@ To use an InputField you define an InputObjectType that specifies the structure
 
     class CreatePerson(graphene.Mutation):
         class Input:
-            person_data = graphene.InputField(PersonInput)
+            person_data = graphene.Argument(PersonInput)
 
         person = graphene.Field(lambda: Person)
 
-        def mutate(self, args, context, info):
+        @staticmethod
+        def mutate(root, args, context, info):
             p_data = args.get('person_data')
 
             name = p_data.get('name')