fix(api): do not include null values for owner fields in ModelMutatio…

…ns helpers

packages/api/amplify_api/analysis_options.yaml

@@ -2,4 +2,5 @@ include: package:amplify_lints/library.yaml
 
 analyzer:
   exclude:
+    - test/test_models/**
     - '**/*.mocks.dart'

packages/api/amplify_api/lib/src/graphql/factories/graphql_request_factory.dart

@@ -315,14 +315,28 @@ class GraphQLRequestFactory {
       }
     }
 
-    // Remove any relational fields or readonly.
+    final ownerFieldNames = (schema.authRules ?? [])
+        .where((authRule) => authRule.ownerField != null)
+        .map((authRule) => authRule.ownerField!)
+        .toSet();
+
+    // In some cases, remove values from the input JSON.
     final fieldsToRemove = schema.fields!.entries
         .where(
-          (entry) => entry.value.association != null || entry.value.isReadOnly,
+          (entry) =>
+              // relational fields
+              entry.value.association != null ||
+              // read-only
+              entry.value.isReadOnly ||
+              // owner fields with null value
+              (ownerFieldNames.contains(entry.value.name) &&
+                  modelJson[entry.value.name] == null),
         )
         .map((entry) => entry.key)
         .toSet();
-    modelJson.removeWhere((key, dynamic value) => fieldsToRemove.contains(key));
+    modelJson.removeWhere(
+      (key, dynamic value) => fieldsToRemove.contains(key),
+    );
 
     return modelJson;
   }

packages/api/amplify_api/test/graphql_helpers_owner_field_test.dart

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+import 'package:amplify_api/src/api_plugin_impl.dart';
+import 'package:amplify_core/amplify_core.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'test_models/owner_field/ModelProvider.dart';
+
+class MockAmplifyAPI extends AmplifyAPIDart {
+  MockAmplifyAPI({
+    super.modelProvider,
+  });
+}
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  group('with ModelProvider manyToMany', () {
+    setUpAll(() async {
+      await Amplify.reset();
+      await Amplify.addPlugin(
+        // needed to fetch the schema from within the helper
+        MockAmplifyAPI(modelProvider: ModelProvider.instance),
+      );
+    });
+
+    test(
+      'ModelMutations.update() will not provide null for an owner field when omitted from model instance',
+      () {
+        final todo = Todo(name: 'mow lawn');
+        final updateReq = ModelMutations.update(todo);
+        final input = updateReq.variables['input'] as Map<String, dynamic>;
+        expect(input.containsKey('owners'), isFalse);
+      },
+    );
+
+    test(
+      'ModelMutations.update() will include an owner field when provided',
+      () {
+        const owners = ['bob'];
+        final todo = Todo(name: 'mow lawn', owners: owners);
+        final updateReq = ModelMutations.update(todo);
+        final input = updateReq.variables['input'] as Map<String, dynamic>;
+        expect(input['owners'], owners);
+      },
+    );
+  });
+}

packages/api/amplify_api/test/test_models/owner_field/ModelProvider.dart

@@ -0,0 +1,49 @@
+/*
+* Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+*
+* Licensed under the Apache License, Version 2.0 (the "License").
+* You may not use this file except in compliance with the License.
+* A copy of the License is located at
+*
+*  http://aws.amazon.com/apache2.0
+*
+* or in the "license" file accompanying this file. This file is distributed
+* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+* express or implied. See the License for the specific language governing
+* permissions and limitations under the License.
+*/
+
+// NOTE: This file is generated and may not follow lint rules defined in your app
+// Generated files can be excluded from analysis in analysis_options.yaml
+// For more info, see: https://dart.dev/guides/language/analysis-options#excluding-code-from-analysis
+
+// ignore_for_file: public_member_api_docs, annotate_overrides, dead_code, dead_codepublic_member_api_docs, depend_on_referenced_packages, file_names, library_private_types_in_public_api, no_leading_underscores_for_library_prefixes, no_leading_underscores_for_local_identifiers, non_constant_identifier_names, null_check_on_nullable_type_parameter, prefer_adjacent_string_concatenation, prefer_const_constructors, prefer_if_null_operators, prefer_interpolation_to_compose_strings, slash_for_doc_comments, sort_child_properties_last, unnecessary_const, unnecessary_constructor_name, unnecessary_late, unnecessary_new, unnecessary_null_aware_assignments, unnecessary_nullable_for_final_variable_declarations, unnecessary_string_interpolations, use_build_context_synchronously
+
+import 'package:amplify_core/amplify_core.dart';
+
+import 'Todo.dart';
+
+export 'Todo.dart';
+
+class ModelProvider implements ModelProviderInterface {
+  @override
+  String version = 'a75dcc30a1e877e7ad8b425e805e0eeb';
+  @override
+  List<ModelSchema> modelSchemas = [Todo.schema];
+  static final ModelProvider _instance = ModelProvider();
+  @override
+  List<ModelSchema> customTypeSchemas = [];
+
+  static ModelProvider get instance => _instance;
+
+  ModelType getModelTypeByModelName(String modelName) {
+    switch (modelName) {
+      case 'Todo':
+        return Todo.classType;
+      default:
+        throw Exception(
+            'Failed to find model in model provider for model name: ' +
+                modelName);
+    }
+  }
+}