fix for codegen rejecting operations that contain fragments with type conditions on interfaces

sgqlc/codegen/operation.py

@@ -149,6 +149,9 @@ def _create_type(self, typ):
         possible_types = typ['possibleTypes'] or typ['interfaces'] or []
         typ['possibleTypes'] = {t['name'] for t in possible_types}
 
+        interfaces = typ['interfaces'] or []
+        typ['interfaces'] = {t['name'] for t in interfaces}
+
         return typ
 
     def _create_field(self, field):
@@ -743,7 +746,8 @@ def enter_inline_fragment(self, node, *_args):
             self.type_stack.append(None)
             return
         type_name = node.type_condition.name.value
-        if type_name not in typ['possibleTypes']:
+        condition_type = self.validation.get_type(type_name)
+        if not self._type_valid_in_fragment(condition_type, typ):
             self.report_possible_type_validation(node, typ, type_name)
 
         try:
@@ -752,6 +756,13 @@ def enter_inline_fragment(self, node, *_args):
         except KeyError as ex:
             self.report_type_validation(node, ex)
 
+    @staticmethod
+    def _type_valid_in_fragment(condition_type, fragment_type):
+        return (
+            fragment_type['name'] in condition_type['interfaces']
+            or condition_type['name'] in fragment_type['possibleTypes']
+        )
+
     def leave_inline_fragment(self, node, *_args):
         self.type_stack.pop()
         return (

tests/test-operation-codegen.py

@@ -0,0 +1,29 @@
+import os
+from io import StringIO
+from graphql import Source
+
+from sgqlc.codegen.operation import CodeGen, load_schema, ParsedSchemaName
+
+
+def test_operation_gen_nested_interface():
+    result_buff = StringIO()
+    test_schema_path = os.path.join(
+        'tests', 'test-resources', 'operation-codegen', 'operation-test.json'
+    )
+    test_op_path = os.path.join(
+        'tests', 'test-resources', 'operation-codegen', 'op-gen.gql'
+    )
+    schema_name = ParsedSchemaName.parse_schema_name('.schema')
+
+    with open(test_op_path) as op_file, open(test_schema_path) as schema_file:
+        operation_gql = [Source(op_file.read(), op_file.name)]
+        schema = load_schema(schema_file)
+        gen = CodeGen(
+            schema,
+            schema_name,
+            operation_gql,
+            result_buff.write,
+            short_names=False,
+        )
+        gen.write()
+        result_buff.close()

tests/test-resources/operation-codegen/op-gen.gql

@@ -0,0 +1,7 @@
+query QueryFieldOnNestedInterface {
+    foo {
+        ... on Bar {
+            barField
+        }
+    }
+}