fix(fdc): errors are now properly propagated to the user (#13433)

* Handled errors

* Only throw errors if errors is not empty

Author: maneesht

packages/firebase_data_connect/firebase_data_connect/example/dataconnect/connector/mutations.gql

@@ -21,6 +21,7 @@ mutation addDateAndTimestamp($date: Date!, $timestamp: Timestamp!) @auth(level:
 mutation seedMovies @auth(level: PUBLIC) {
   the_matrix: movie_insert(
     data: {
+      id: "09d5f835656c467787347668bbb44522"
       title: "The Matrix"
       releaseYear: 1999
       genre: "Sci-Fi"
@@ -70,6 +71,7 @@ mutation thing($title: Any! = "ABC") @auth(level: PUBLIC) {
 mutation seedData @auth(level: PUBLIC) {
   the_matrix: movie_insert(
     data: {
+      id: "09d5f835656c467787347668bbb44522"
       title: "The Matrix"
       releaseYear: 1999
       genre: "Action"

packages/firebase_data_connect/firebase_data_connect/lib/src/network/grpc_transport.dart

@@ -137,6 +137,9 @@ class GRPCTransport implements DataConnectTransport {
     try {
       response = await stub.executeMutation(request,
           options: CallOptions(metadata: await getMetadata()));
+      if (response.errors.isNotEmpty) {
+        throw Exception(response.errors);
+      }
       return deserializer(jsonEncode(response.data.toProto3Json()));
     } on Exception catch (e) {
       throw DataConnectError(DataConnectErrorCode.other,

packages/firebase_data_connect/firebase_data_connect/lib/src/network/rest_transport.dart

@@ -112,6 +112,14 @@ class RestTransport implements DataConnectTransport {
                 ? DataConnectErrorCode.unauthorized
                 : DataConnectErrorCode.other,
             "Received a status code of ${r.statusCode} with a message '${message}'");
+      } else {
+        Map<String, dynamic> bodyJson =
+            jsonDecode(r.body) as Map<String, dynamic>;
+        if (bodyJson.containsKey("errors") &&
+            (bodyJson['errors'] as List).isNotEmpty) {
+          throw DataConnectError(
+              DataConnectErrorCode.other, bodyJson['errors'].toString());
+        }
       }
 
       /// The response we get is in the data field of the response

packages/firebase_data_connect/firebase_data_connect/test/src/network/rest_transport_test.dart

@@ -223,5 +223,33 @@ void main() {
         body: anyNamed('body'),
       )).called(1);
     });
+    test('invokeOperation should throw an error if the server throws one',
+        () async {
+      final mockResponse = http.Response("""
+{
+    "data": {},
+    "errors": [
+        {
+            "message": "SQL query error: pq: duplicate key value violates unique constraint movie_pkey",
+            "locations": [],
+            "path": [
+                "the_matrix"
+            ],
+            "extensions": null
+        }
+    ]
+}""", 200);
+      when(mockHttpClient.post(any,
+              headers: anyNamed('headers'), body: anyNamed('body')))
+          .thenAnswer((_) async => mockResponse);
+
+      final deserializer = (String data) => 'Deserialized Data';
+
+      expect(
+        () => transport.invokeOperation(
+            'testQuery', deserializer, null, null, 'executeQuery'),
+        throwsA(isA<DataConnectError>()),
+      );
+    });
   });
 }