颤动天气应用编程接口不工作snapshot.data显示错误

Question

Main.dart

import 'package:flutter/material.dart';
import 'package:flutter_application_1/currentWeather.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: CurrentWeatherPage(),
    );
  }
}

models/weather.dart

class Weather {
  final double temp;
  final double feelslike;
  final double low;
  final double high;
  final double description;

  Weather({ required this.temp, required this.feelslike, required this.low, required this.high, required this.description});

  factory Weather.fromjson(Map<String, dynamic>json) {
    return Weather(
      temp: json['main']['temp'].toDouble(),
      feelslike: json['main']['feels_like'].toDouble(),
      low: json['main']['temp_min'].toDouble(),
      high: json['main']['temp_max'].toDouble(),
      description: json['weather'][0]['description'],
    );
  }
}

currentWeather.dart

import 'dart:convert';
import 'package:http/http.dart' as http;
import 'package:flutter/material.dart';
import 'package:flutter_application_1/models/weather.dart';

class CurrentWeatherPage extends StatefulWidget{

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

class _CurrentWeatherPageState extends State<CurrentWeatherPage> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: FutureBuilder(
          builder: (context, snapshot){
            // ignore: unnecessary_null_comparison
            if (snapshot != null){
              Weather _weather = snapshot.data;
              // ignore: unnecessary_null_comparison
              if (_weather == null){
                return Text("ERROR GETING WEATHER");
              } else {
                return weatherBox(_weather);
              }
            } else{
              return CircularProgressIndicator();
            }
          },
          future: getCurrentWeather(),
        ),
        ),
    );
  }  

  Widget weatherBox(Weather _weather){
    return Column(
      children: <Widget>[
        Text("${_weather.temp}°c"),
        Text("${_weather.description}"),
        Text("${_weather.feelslike}°c"),
        Text("H:${_weather.high}°c L:${_weather.low}°c"),
      ],
    );
  }
}

Future getCurrentWeather() async {
  Weather weather;
  String city = "chennai";
  String apikey = "safdgfdsgvf";
  var url = Uri.parse("api.openweathermap.org/data/2.5/weather?q=$city&appid=$apikey");

  final response = await http.get(url);

  if (response.statusCode == 200) {
    weather = Weather.fromjson(jsonDecode(response.body));
  }else {
    weather = Weather.fromjson(jsonDecode(response.body));
  }
   return weather;
}

在currentWeather.dart中

Weather _weather = snapshot.data;

snapshot.data显示错误：'Object?‘类型的值不能赋值给'Weather‘类型的变量。尝试更改变量的类型，或将右侧类型强制转换为“Weather”。.dart(Invalid_assignment)

如何解决此错误？

Answer 1

您应该将Map对象的snapshot.data转换为Weather对象。

Weather _weatherl = Weather.fromjson(snapshot.data!.data());
// Output of this code is depend on how is your data structured in the database and Weather model you have defined here.