CODEWITHSUNDEEP
flutter
Eike
Eike

Reputation: 2431

Flutter Method Channel Pass JSON

I'm trying out flutter modules for my current project. Pushing a flutter view is quite nice and works like a charm. Now I'm trying to pass over some JSON data but I can't managed to receive the data and parse it into a Map<String, dynamic>. My implementation looks like the following. Any idea?

iOS 

 guard let path = Bundle.main.path(forResource: "chat", ofType: "json") else {
        return
    }
    let data = try! Data(contentsOf: URL(fileURLWithPath: path), options: .mappedIfSafe)

    let flutterEngine = (UIApplication.shared.delegate as? AppDelegate)?.flutterEngine;
    let flutterViewController = FlutterViewController(engine: flutterEngine, nibName: nil, bundle: nil)!;
    flutterViewController.send(onChannel: "chat.json", message: data)

    flutterViewController.setMessageHandlerOnChannel("chat.result") {
        (message: Data!, reply: FlutterBinaryReply) -> Void in
        print("get json from result")
        self.navigationController?.popViewController(animated: true);
    }
    self.navigationController?.pushViewController(flutterViewController, animated: true)

Dart

void initState() {
    const channel = BasicMessageChannel('chat.json', JSONMessageCodec());
    // Receive messages from platform and send replies.
    channel.setMessageHandler((dynamic message) async {
      print('Received: $message');
      return 'Hi from Dart';
    });

what am I doing wrong?

Upvotes: 2

Views: 3079

Answers (1)

Yadong Zhao
Yadong Zhao

Reputation: 21

If you want to pass JSON struct as params to Android/IoS by flutter channel, you can do it like this:

  • receive params use: call.arguments as? Dictionary<String, Any>
  • get param from the first step use guard let paramName = args?["paramName"] as? String
  • decode json string by JSONDecoder package

otherwise, if you want to return JSON string to flutter point, you can use JSONEncoder package to encode IoS struct.

But, I don't know how to receive JSON struct for Android platform, when I get it, I will complete the answer, good luck!

Update:

If you use dart class as param,please make sure your class has toJson func,like this:

Map<String, dynamic> toJson() =>
    {
      'name': name,
      'email': email,
    };

And 

jsonEncode(your_class.toMap()).

For Android platform parse:

val args = call.arguments as Map<String,Any>
val argName = args["argName"] as String
Klaxon().parse<TargetDataClass>(argName)

Upvotes: 1

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