Send Map/JSON from Flutter to Android through Method channel

Question

I've set up a basic method channel in Dart and Kotlin

Dart Code

  Future<void> _updateProfile() async {
    try {
      var result = await platform.invokeMethod('updateProfile');
      print(result);
    } on PlatformException catch (e) {
      print('Failed to get battery level: ${e.message}');
    }

    setState(() {
//      print('Setting state');
    });
  }

Kotlin Code

MethodChannel(flutterView, channel).setMethodCallHandler { call, result ->
      if(call.method == "updateProfile"){
        val actualResult = updateProfile()

        if (actualResult.equals("Method channel Success")) {
          result.success(actualResult)
        } else {
          result.error("UNAVAILABLE", "Result was not what I expected", null)
        }
      } else {
        result.notImplemented()
      }
    }

I want to pass a JSON/Map data to the Kotlin side. My data looks like this:

{    
    "user_dob":"15 November 1997", 
    "user_description":"Hello there, I am a User!", 
    "user_gender":"Male", 
    "user_session":"KKDSH3G9OJKJFIHXLJXUGWIOG9UJKLJ98WHIJ"
}

How can I pass this data from dart to kotlin?

Answer 1

You can pass parameter with method call. Like,

var data = {    
"user_dob":"15 November 1997", 
"user_description":"Hello there, I am a User!", 
"user_gender":"Male", 
"user_session":"KKDSH3G9OJKJFIHXLJXUGWIOG9UJKLJ98WHIJ"
}

Future<void> _updateProfile() async {
    try {
      var result = await platform.invokeMethod('updateProfile', data);
      print(result);
    } on PlatformException catch (e) {
      print('Failed : ${e.message}');
    }
  }

And get result in kotlin using call.arguments

MethodChannel(flutterView, channel).setMethodCallHandler { call, result ->
     var argData = call.arguments       //you can get data in this object.
}

Answer 2

Map Json:

{    
    "user_dob":"15 November 1997", 
    "user_description":"Hello there, I am a User!", 
    "user_gender":"Male", 
    "user_session":"KKDSH3G9OJKJFIHXLJXUGWIOG9UJKLJ98WHIJ"
}

Kotlin Code：

MethodChannel(flutterView, channel).setMethodCallHandler { call, result ->
    //you can get data in this object.
    val user_dob = call.argument<String>("user_dob")
    val user_description = call.argument<String>("user_description")
    val user_gender = call.argument<String>("user_gender")
    val user_session = call.argument<String>("user_session")
}

Answer 3

Dart side (sending Map):

var channel = MethodChannel('foo_channel');
var map = <String, dynamic>{
  'key': 'value',
};
await channel.invokeListMethod<String>('methodInJava', map);

Java side (receiving Map):

if (methodCall.method.equals("methodInJava")) {
    // Map value.
    HashMap<String, Object> map = (HashMap<String, Object>) methodCall.arguments;
    Log.i("MyTag", "map = " + map); // {key=value}
}