Class 'List<dynamic>' has no instance method 'cast' with matching arguments

Flutter
6

Hi, I’ve run into a similar issue following the backendless missions, using Flutter SDK to make a query in the database.

The SDK version is the latest one:

backendless_sdk: ^7.0.0-nullsafety.0

I was forced to use the latest (beta) version of Backendless Flutter SDK because the previous wouldn’t fit the dependencies I had (Firebase).

Details:

Specifically, the “Find” method is returning null internally and is unable to cast it to a map. The issue happens in the following code in data_store.dart.

Future<List<Map?>?> find([DataQueryBuilder? queryBuilder]) async =>
      (await _channel.invokeMethod(
              "Backendless.Data.of.find", <String, dynamic>{
        'tableName': _tableName,
        'queryBuilder': queryBuilder
      }))
          .cast<Map?>();

The error is:

E/flutter (30590): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: NoSuchMethodError: The method 'cast' was called on null.
E/flutter (30590): Receiver: null
E/flutter (30590): Tried calling: cast<Map<dynamic, dynamic>?>()

Pretty sure that’s an issue with the null safety.

My own code is extremely simple:

var queryBuilder = DataQueryBuilder()..whereClause = "Name = 'Dallas'";

var response = await Backendless.data.of("City").find(queryBuilder);

Good luck fixing this, because effectively we can’t do any querying whatsoever as of now. Please make this an urgent fix!

@Minh_Tuan_Vu It’s very helpful to the developers to provide more information on your problem. If you’re under pressure, it should be the first thing you do!