# gridRepository method Null safety

1. @override

GridRepository? gridRepository(

1. String? appId

)
override

## Implementation

    @override
    GridRepository? gridRepository(String? appId) {
      if ((appId != null) && (_gridRepository[appId] == null)) {
        _gridRepository[appId] = GridCache(GridFirestore(
            () => appRepository()!.getSubCollection(appId, 'grid'), appId));
      }
      return _gridRepository[appId];
    }