Support recursive input object types in build_ast_schema

Author: mwilliamson

graphql/utils/build_ast_schema.py

@@ -234,7 +234,7 @@ def make_scalar_def(definition):
     def make_input_object_def(definition):
         return GraphQLInputObjectType(
             name=definition.name.value,
-            fields=make_input_values(definition.fields, GraphQLInputObjectField)
+            fields=lambda: make_input_values(definition.fields, GraphQLInputObjectField)
         )
 
     _schema_def_handlers = {

graphql/utils/tests/test_build_ast_schema.py

@@ -411,6 +411,25 @@ def test_input_types_are_read():
     assert input_type.fields["id"].type == GraphQLInt
 
 
+def test_input_types_can_be_recursive():
+    schema = build_ast_schema(parse("""
+        schema {
+            query: Query
+        }
+
+        type Query {
+            field(input: Input): Int
+        }
+
+        input Input {
+            id: Input
+        }
+    """))
+
+    input_type = schema.get_type("Input")
+    assert input_type.fields["id"].type == input_type
+
+
 def test_simple_argument_field_with_default():
     body = '''
 schema {