CODEWITHSUNDEEP
flutterdart
NinFudj
NinFudj

Reputation: 129

Trouble initializing a <Position> variable in Flutter LateInitializationError: Field '____ ' has not been initialized

newbie to Flutter. My code runs but encounters a

The following LateError was thrown building FutureBuilder(dirty, state: _FutureBuilderState#e1a6f): LateInitializationError: Field 'initialPosition' has not been initialized.

The code is to set up a GoogleMap widget that takes initial position from the device. I get the red screen with that error, but after a few seconds the coordinates gets received and proceeds as normal and displays the map and position correctly. Tried future as well but but I get other errors. Is it supposed to be under the FutureBuilder? In a wrapper.dart or my main.dart?

home.dart:

import 'package:flutter/material.dart';
import 'package:something/services/auth.dart';
import 'screens/map.dart';
import 'package:something/services/geolocator_service.dart';

class LakoApp extends StatefulWidget {
  @override


  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<LakoApp> {

  final AuthService _auth = AuthService();
  final _geolocatorService = GeolocatorService();
  late var initialPosition;

  // @override


  Future getInitialPosition <Position>() async {
    initialPosition = await _geolocatorService.getInitialLocation();
    return initialPosition;
  }

  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: FittedBox(
            child: Text('Something something'),
          ),
          actions: <Widget>[
           // irrelevant code
           // .....
           
          
        ],
        body:

        FutureBuilder(

            future: getInitialPosition(),
            builder: (context, snapshot) {
               return Map(initialPosition);
   
            }
        )
    );
  }  
  }

Upvotes: 1

Views: 2538

Answers (2)

NinFudj
NinFudj

Reputation: 129

Edited the code according to suggestions: got rid of the method and variable, because its redundant

body: FutureBuilder <Position> (
        future: _geolocatorService.getInitialLocation(),
        builder: (context, snapshot) {
          if (snapshot.hasData) {
            return Map(snapshot.data!);
          }else {
            return Loading();

Upvotes: 1

Cavitedev
Cavitedev

Reputation: 761

Future Builders are built even before getting the data. So, you should check whether it has data.

 if (snapshot.hasData) {
                return Map(initialPosition); //Or snapshot.data.
              }else{
                return CircularProgressIndicator();
              }

There are other problems here. I will show some further code to improve your own code.

Your method returns a Future of any type receiving a generic parameter called Position. I think you want to use a data type called position for that you need to move <Position> here as right now the way you are writing it is useless for your specific example.

Future<Position> getInitialPosition () async {
    initialPosition = await _geolocatorService.getInitialLocation();
    return initialPosition;
  }

The FutureBuilder can be like this.

FutureBuilder<Position>(
            future: getInitialPosition(),
            builder: (context, snapshot) {
                if (snapshot.hasData) {
                return Map(snapshot.data);
              }else{
                return CircularProgressIndicator(); 
                //Display loading, you may adapt this widget to your interface or use some state management solution
              }
            }
        )

Upvotes: 1

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