Trying to display an alert when I get a null value for the weather data-CodePudding

trying to display an alert or warning as a way of catching an error when weatherData is set to null. but when I test it or try to turn of location the spinkit just keeps loading and does not move to the location_screen to display the alert message. I used a condition under updateUI to display the message when weatherData == null.

import 'package:clima_app/services/weather.dart';
import 'package:flutter/material.dart';
import 'package:quickalert/models/quickalert_type.dart';
import 'package:quickalert/widgets/quickalert_dialog.dart';

import '../utilities/constants.dart';

class LocationScreen extends StatefulWidget {
  const LocationScreen({super.key, this.locationWeather});

  final dynamic locationWeather;

  @override
  State<LocationScreen> createState() => _LocationScreenState();
}

class _LocationScreenState extends State<LocationScreen> {
  WeatherModel weather = WeatherModel();
  late int temperature;
  late String weatherIcon;
  late String cityName;
  late String weatherMessage;

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

  void updateUI(dynamic weatherData) {
    setState(() {

      //This is the condition for showing the alert message
      if (weatherData == null) {
        QuickAlert.show(
          context: context,
          type: QuickAlertType.error,
          title: 'Error',
          text: 'Oops! Something went wrong.',
          textColor: Colors.red,
        );
        return;
      }
      double temp = weatherData['main']['temp'];
      temperature = temp.toInt();
      var condition = weatherData['weather'][0]['id'];
      weatherIcon = weather.getWeatherIcon(condition);
      weatherMessage = weather.getMessage(temperature);
      cityName = weatherData['name'];
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        decoration: BoxDecoration(
          image: DecorationImage(
            image: const AssetImage('images/location_background.jpg'),
            fit: BoxFit.cover,
            colorFilter: ColorFilter.mode(Colors.white.withOpacity(0.8), BlendMode.dstATop),
          ),
        ),
        constraints: const BoxConstraints.expand(),
        child: SafeArea(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: <Widget>[
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: <Widget>[
                  OutlinedButton(
                    onPressed: () async {
                      var weatherData = await weather.getLocationWeather();
                      updateUI(weatherData);
                    },
                    child: const Icon(
                      Icons.near_me,
                      size: 50.0,
                    ),
                  ),
                  OutlinedButton(
                    onPressed: () {},
                    child: const Icon(
                      Icons.location_city,
                      size: 50.0,
                    ),
                  ),
                ],
              ),
              Padding(
                padding: const EdgeInsets.only(left: 15.0),
                child: Row(
                  children: <Widget>[
                    Text(
                      '$temperature°',
                      style: kTempTextStyle,
                    ),
                    Text(
                      weatherIcon,
                      style: kConditionTextStyle,
                    ),
                  ],
                ),
              ),
              Padding(
                padding: const EdgeInsets.only(right: 15.0),
                child: Text(
                  "$weatherMessage in $cityName",
                  textAlign: TextAlign.right,
                  style: kMessageTextStyle,
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

This is the first screen from which the location screen is pushed...

import 'package:clima_app/screens/location_screen.dart';
import 'package:clima_app/services/weather.dart';
import 'package:flutter/material.dart';
import 'package:flutter_spinkit/flutter_spinkit.dart';
import 'package:geolocator/geolocator.dart';

class LoadingScreen extends StatefulWidget {
  const LoadingScreen({super.key});

  @override
  State<LoadingScreen> createState() => _LoadingScreenState();
}

class _LoadingScreenState extends State<LoadingScreen> {
  @override
  void initState() {
    super.initState();
    getLocationData();
  }

  void getLocationData() async {
    bool serviceEnabled;
    LocationPermission permission;

    // Test if location services are enabled.
    serviceEnabled = await Geolocator.isLocationServiceEnabled();
    if (!serviceEnabled) {
      // Location services are not enabled don't continue
      // accessing the position and request users of the
      // App to enable the location services.
      return Future.error('Location services are disabled.');
    }

    permission = await Geolocator.checkPermission();
    if (permission == LocationPermission.denied) {
      permission = await Geolocator.requestPermission();
      if (permission == LocationPermission.denied) {
        // Permissions are denied, next time you could try
        // requesting permissions again (this is also where
        // Android's shouldShowRequestPermissionRationale
        // returned true. According to Android guidelines
        // your App should show an explanatory UI now.
        return Future.error('Location permissions are denied');
      }
    }

    if (permission == LocationPermission.deniedForever) {
      // Permissions are denied forever, handle appropriately.
      return Future.error(
          'Location permissions are permanently denied, we cannot request permissions.');
    }

    //END OF TEST... END OF TEST... END OF TEST... END OF TEST... END OF TEST... END OF TEST

    var weatherData = await WeatherModel().getLocationWeather();

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

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      body: Center(
        child: SpinKitWave(
          size: 50.0,
          color: Colors.blueAccent,
        ),
      ),
    );
  }
}

This is location.dart which has the geolocater package where I placed the try and catch error:

import 'package:geolocator/geolocator.dart';

class Location {
  late double latitude;
  late 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);
    }
  }
}

And this is the network.dart which has the http.get response

import 'dart:convert';

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

class NetworkHelper {
  NetworkHelper(this.url);

  final String url;

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

    if (response.statusCode == 200) {
      String data = response.body;

      return jsonDecode(data);
    } else {
      print(response.statusCode);
    }
  }
}

CodePudding user response：

change updateUI to this:

void updateUI(dynamic weatherData) {
    
    if (weatherData == null) {
        QuickAlert.show(
          context: context,
          type: QuickAlertType.error,
          title: 'Error',
          text: 'Oops! Something went wrong.',
          textColor: Colors.red,
        );
        
    }else {
        double temp = weatherData['main']['temp'];
        temperature = temp.toInt();
        var condition = weatherData['weather'][0]['id'];
        weatherIcon = weather.getWeatherIcon(condition);
        weatherMessage = weather.getMessage(temperature);
        cityName = weatherData['name'];
        setState(() {});
    }
  }

CodePudding user response：

try this, please fix comma and semi-col-

  void updateUI(dynamic weatherData, BuildContext context) {

if (weatherData == null) {

    showDialog(context: context, builder: ((context) => AlertDialog(titleTextStyle: "Oops! Something went wrong.", actions: [
      TextButton(onPressed: () => Navigator.of(context).pop(), child: Text('Okhy'))
    ],)))
    
}else {
    double temp = weatherData['main']['temp'];
    temperature = temp.toInt();
    var condition = weatherData['weather'][0]['id'];
    weatherIcon = weather.getWeatherIcon(condition);
    weatherMessage = weather.getMessage(temperature);
    cityName = weatherData['name'];
    setState(() {});
}

}