Getting the Tried calling: []("main") error

Question

Hi I am working on the London Brewery clima app but I am getting the Tried calling:. I have already looked up other solutions to this problem but they didn't work.

This is my code:

MAIN.DART

import 'package:flutter/material.dart';
import 'package:clima/screens/loading_screen.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark(),
      home: LoadingScreen(),
    );
  }
}

LOCATION SCREEN

import 'package:flutter/material.dart';
import 'package:clima/utilities/constants.dart';

class LocationScreen extends StatefulWidget {
  LocationScreen({this.locationWeather});

  final locationWeather;

  @override
  _LocationScreenState createState() => _LocationScreenState();
}

class _LocationScreenState extends State<LocationScreen> {
  double temperature;
  int condition;
  String cityName;

  @override
  void initState() {
    super.initState();
    updateUI(widget.locationWeather);
  }

  void updateUI(dynamic weatherData) {
    temperature = weatherData['main']['temp'];
    condition = weatherData['weather'][0]['id'];
    cityName = weatherData['name'];
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        decoration: BoxDecoration(
          image: DecorationImage(
            image: AssetImage('images/location_background.jpg'),
            fit: BoxFit.cover,
            colorFilter: ColorFilter.mode(
                Colors.white.withOpacity(0.8), BlendMode.dstATop),
          ),
        ),
        constraints: BoxConstraints.expand(),
        child: SafeArea(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: <Widget>[
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: <Widget>[
                  FlatButton(
                    onPressed: () {},
                    child: Icon(
                      Icons.near_me,
                      size: 50.0,
                    ),
                  ),
                  FlatButton(
                    onPressed: () {},
                    child: Icon(
                      Icons.location_city,
                      size: 50.0,
                    ),
                  ),
                ],
              ),
              Padding(
                padding: EdgeInsets.only(left: 15.0),
                child: Row(
                  children: <Widget>[
                    Text(
                      '32°',
                      style: kTempTextStyle,
                    ),
                    Text(
                      '☀️',
                      style: kConditionTextStyle,
                    ),
                  ],
                ),
              ),
              Padding(
                padding: EdgeInsets.only(right: 15.0),
                child: Text(
                  "It's 🍦 time in San Francisco!",
                  textAlign: TextAlign.right,
                  style: kMessageTextStyle,
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

LOADING SCREEN

import 'package:flutter/material.dart';
import 'package:clima/services/location.dart';
import 'package:clima/services/networking.dart';
import 'location_screen.dart';
import 'package:flutter_spinkit/flutter_spinkit.dart';

const apiKey = '6e0c9beb6379456cd88d1fc1cdcbe15c';

class LoadingScreen extends StatefulWidget {
  @override
  _LoadingScreenState createState() => _LoadingScreenState();
}

class _LoadingScreenState extends State<LoadingScreen> {
  double latitude;
  double longitude;

  @override
  void initState() {
    super.initState();
    getLocationData();
  }

  void getLocationData() async {
    Location location = Location();
    await location.getCurrentLocation();
    latitude = location.longitude;
    longitude = location.latitude;
    NetworkHelper networkHelper = NetworkHelper(
        'https://api.openweathermap.org/data/2.5/weather?lat=$latitude&lon=$longitude&appid=$apiKey&units=metric');

    var weatherData = await networkHelper.getData();

    Navigator.push(context, MaterialPageRoute(builder: (context) {
      return LocationScreen(
        locationWeather: weatherData,
      );
    }));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
          child: SpinKitDoubleBounce(
        color: Colors.white,
        size: 100.0,
      )),
    );
  }
}

LOCATION SCREEN

import 'package:geolocator/geolocator.dart';

class Location {
  Location({this.latitude, this.longitude});

  double latitude;
  double longitude;

  Future<void> getCurrentLocation() async {
    try {
      Position position = await Geolocator()
          .getCurrentPosition(desiredAccuracy: LocationAccuracy.low);
      latitude = position.latitude;
      longitude = position.longitude;
    } catch (e) {
      print(e);
    }
  }
}

NETWORKING

import 'package:http/http.dart' as http;
import 'dart:convert';

class NetworkHelper {
  NetworkHelper(this.url);

  final String url;

  Future getData() async {
    http.Response response = await http.get(url);

    if (response.statusCode == 200) {
      String data = response.body;
      return jsonDecode(data);
    } else {
      print(response.statusCode);
    }
  }
}

I have already tried the next on the networking

String data = response.body;
      var output = jsonDecode(data);
      return output;
    } else {
      print(response.statusCode);

but it didn't work.

Could anyone help me out with this?

Thanks to all Diego

Answer 1

Given the following JSON from the openweathermap API call, notice that main property is not a List but a Map .

{
  "coord": {
    "lon": 0,
    "lat": 0
  },
  "weather": [
    {
      "id": 804,
      "main": "Clouds",
      "description": "overcast clouds",
      "icon": "04n"
    }
  ],
  "base": "stations",
  "main": {
    "temp": 23.22,
    "feels_like": 23.56,
    "temp_min": 23.22,
    "temp_max": 23.22,
    "pressure": 1015,
    "humidity": 75,
    "sea_level": 1015,
    "grnd_level": 1015
  },
  "visibility": 10000,
  "wind": {
    "speed": 4.73,
    "deg": 161,
    "gust": 5
  },
  "clouds": {
    "all": 100
  },
  "dt": 1658528443,
  "sys": {
    "sunrise": 1658469763,
    "sunset": 1658513388
  },
  "timezone": 0,
  "id": 6295630,
  "name": "Globe",
  "cod": 200
}

But the updateUI function is trying to access it as List . The fix is pretty simple, just remove the [0] from temperature = weatherData['main'][0]['temp']; like below:

  void updateUI(dynamic weatherData) {
    temperature = weatherData['main']['temp'];    // <- Fix here
    condition = weatherData['weather'][0]['id'];
    cityName = weatherData['name'];
  }

Answer 2

Thanks all for your help. I went ahead with the project and with the same code just worked fine. I don't know what changed actually but it works now. Thanks all