CODEWITHSUNDEEP
flutter
rozerro
rozerro

Reputation: 7156

How can I get a real string value from Future<String> in widget?

Instead of expected string value I get the Instance of Future<String> in my widget: (in the second line of winget should be a string value of 373,8)

(_rapport.isNotEmpty && _rapport.length == 3)
  ? Text((_distortion(_rapport, widget.printer)).toString()) // this function return Future<String>
  : const Text(''), // rapport is empty

The function is:

Future<String> _distortion(String rapport, String printer) async {
    final String record = await _getRecord(rapport);

    print('record: ${record.toString()}'); // this gives me an expected valid output

    final List row = record.toString().split(';');
    final String d1 = row[1]; // tachys
    final String d2 = row[3]; // onyx

    switch (printer) {
      case 'Tachys':
        {
          print('distortion: $d1'); // output: distortion: 373,8
          return d1;
        }
        break;

      default:
        {
          print('distortion: $d2');
          return d2;
        }
    }
  }

How can I get real value from Future in widget?

Upvotes: 2

Views: 268

Answers (3)

Guru Prasad mohapatra
Guru Prasad mohapatra

Reputation: 1969

Either you can call the method in initState() and set the value else use FutureBuilder for handling future value.You can have a look at the documentation of FutureBuilder

Upvotes: 0

Mohamed Gaber
Mohamed Gaber

Reputation: 1745

The way to do that is using FutureBuilder() widget .

Change your build function to following

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: FutureBuilder(
      future : _distortion()
        builder: (BuildContext context, AsyncSnapshot snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.waiting:
              return new Text('Loading....');
            default:
              if (snapshot.hasError)
                return new Text('Error: ${snapshot.error}');
              else
                return (_rapport.isNotEmpty && _rapport.length == 3)
          ? Text(snapshot.data) 
          : (_rapport.isNotEmpty && _rapport.length < 3)
          ? const Text('wrong rapport')
          : const Text(''), // rapport is empty
   );
          }

},
      ),
    );
  }

Upvotes: 1

Hamza Khliefat
Hamza Khliefat

Reputation: 21

I thinks you must to add async await when you call (_distortion) function as below:

(_rapport.isNotEmpty && _rapport.length == 3)
  ? Text(await (_distortion(_rapport, widget.printer)).toString()) // this function return Future<String>
  : (_rapport.isNotEmpty && _rapport.length < 3)
      ? const Text('wrong rapport')
      : const Text(''),

Upvotes: 0

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