A value of type can't be returned from method because it has a return type of

user_11381650 0
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List<String> getData() async {
    var response = await http.get(url);

    if (response.statusCode == 200) {
        String data = response.body;
        print(data);
        var temperature = jsonDecode(data)['main']['temp'];
        var condition = jsonDecode(data)['weather'][0]['id'];
        var city_name = jsonDecode(data)['name'];

        return [temperature, condition, city_name];
        } else {
             print(response.statusCode);
        }
   }
}

I get a strange error saying that I can't return List<String> because is expecting List<String> to be returned.

dart flutter
2 Answers

Since the function get data is is async it should return Future<List<String>> example is as follows:

Future<List<String>> getData() async {
    var response = await http.get(url);

    if (response.statusCode == 200) {
        String data = response.body;
        print(data);
        var temperature = jsonDecode(data)['main']['temp'];
        var condition = jsonDecode(data)['weather'][0]['id'];
        var city_name = jsonDecode(data)['name'];

        return <String>[temperature, condition, city_name];
    } else {
             print(response.statusCode);
    }

}

Also your are decoding 3 times unnecessarily, you can do it once keep it in var and use for further usage, example as follows:

String data = response.body;
var decodedData = jsonDecode(data);
var temperature = decodedData['main']['temp'];
var condition = decodedData['weather'][0]['id'];
var city_name = decodedData['name'];
user_27152920

As a generalization, when you get this error in an async function:

A value of type x can't be returned from method because it has a return type of x

The message seems weird, but it could mean that you are missing a Future<> return type.

So add Future<> to your method return type:

Example:

  List<String> getValues() async
  {
    List<String> list = await getJson();
    return list;
  }

Change to:

  Future<List<String>> getValues() async
  {
    List<String> list = await getJson();
    return list;
  }
user_4363410
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