Fixed Dynamic arguments

Author: syrusakbary

graphene/types/argument.py

@@ -36,6 +36,10 @@ def to_arguments(args, extra_args):
     for default_name, arg in iter_arguments:
         if isinstance(arg, Dynamic):
             arg = arg.get_type()
+            if arg is None:
+                # If the Dynamic type returned None
+                # then we skip the Argument
+                continue
 
         if isinstance(arg, UnmountedType):
             arg = arg.Argument()

graphene/types/tests/test_mutation.py

@@ -49,6 +49,7 @@ class CreateUser(Mutation):
         class Input:
             name = String()
             dynamic = Dynamic(lambda: String())
+            dynamic_none = Dynamic(lambda: None)
 
         name = String()
         dynamic = Dynamic(lambda: String())