Change form valid method names

docs/form-mutations.rst

@@ -60,7 +60,7 @@ Form validation
 
 Form mutations will call ``is_valid()`` on your forms.
 
-If the form is valid then ``perform_mutate(form, info)`` is called on the mutation. Override this method to change how
+If the form is valid then ``form_valid(form, info)`` is called on the mutation. Override this method to change how
 the form is saved or to return a different Graphene object type.
 
 If the form is *not* valid then a list of errors will be returned. These errors have two fields: ``field``, a string

graphene_django/forms/mutation.py

@@ -64,19 +64,23 @@ def mutate(cls, root, args, context, info):
         form = cls.get_form(root, args, context, info)
 
         if form.is_valid():
-            return cls.perform_mutate(form, info)
+            return cls.form_valid(form, info)
         else:
-            errors = [
-                ErrorType(field=key, messages=value)
-                for key, value in form.errors.items()
-            ]
-            return cls(errors=errors)
+            return cls.form_invalid(form, info)
 
     @classmethod
-    def perform_mutate(cls, form, info):
+    def form_valid(cls, form, info):
         form.save()
         return cls(errors=[])
 
+    @classmethod
+    def form_invalid(cls, form, info):
+        errors = [
+            ErrorType(field=key, messages=value)
+            for key, value in form.errors.items()
+        ]
+        return cls(errors=errors)
+
     @classmethod
     def get_form(cls, root, args, context, info):
         form_data = args.get(cls._meta.input_field_name)
@@ -151,7 +155,7 @@ class ModelFormMutation(six.with_metaclass(ModelFormMutationMeta, BaseFormMutati
     errors = graphene.List(ErrorType)
 
     @classmethod
-    def perform_mutate(cls, form, info):
+    def form_valid(cls, form, info):
         obj = form.save()
         kwargs = {cls.return_field_name: obj}
         return cls(errors=[], **kwargs)