从另一个类调用方法（Flutter）

Question

我是 Flutter 新手，正在尝试从 API 获取数据。我无法从另一个类调用我的方法，即使它是导入的。我试图从 weather_service.dart 调用 weather_page.dart 中的特定方法。你能帮我吗？

weather_service.dart

import 'dart:convert';
import 'package:testapp/models/weather_model.dart';
import 'package:http/http.dart' as http;

class WeatherService {

  //static const BASE_URL = 'https://api.openweathermap.org/data/2.5/forecast?q=Kutahya,tr&cnt=5&appid=e6080829dff63e16ef3e9756b2e4b0bd';
  static const baseUrl = 'https://api.openweathermap.org/data/2.5/weather?';
  final String apiKey; //The “final” keyword is used to declare variables whose values cannot be changed once assigned. When a variable is declared as final, it can only be assigned a value once, either at its declaration or within the constructor of the class.

  WeatherService(this.apiKey){
    Future<Weather> getWeather(String city, String country) async {
      final response = await http.get(Uri.parse('$baseUrl?q=$city,$country&appid=$apiKey&units=metric'));

      if (response.statusCode == 200) {
        return Weather.fromJson(jsonDecode(response.body));
      } else {
        throw Exception('Failed to get Data');
      }
    }
  }
}

weather_page.dart

import 'package:flutter/material.dart';
import 'package:testapp/models/weather_model.dart';
import 'package:testapp/services/weather_service.dart';

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

  @override
  State<WeatherPage> createState() => _WeatherPageState();
}

class _WeatherPageState extends State<WeatherPage> {

  //set api key
  final _weatherService = WeatherService('e6080829dff63e16ef3e9756b2e4b0bd');
  Weather? _weather; //imported from models/weather_model

  //set city and country
  String city = 'Kutahya'; //You may use Geolocator to get them automatically also.
  String country = 'tr';

  //get data
  _fetchWeather() async {
    try {
      final weather = await _weatherService.getWeather(city, country);
      setState(() {
        _weather = weather;
      });
    }
    catch (e){
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    return const Scaffold();
  }
}

我尝试从 weather_service.dart 调用名为 apiKey 的变量并且它有效。我想它导入正确，也许我的方法有问题。谢谢各位的解答。

Answer 1

您可以通过这样做来修复

class WeatherService {
  //static const BASE_URL = 'https://api.openweathermap.org/data/2.5/forecast?q=Kutahya,tr&cnt=5&appid=e6080829dff63e16ef3e9756b2e4b0bd';
  static const baseUrl = 'https://api.openweathermap.org/data/2.5/weather?';
  final String apiKey;

  WeatherService({required this.apiKey});

  Future<Map<String, dynamic>> getWeather(String city, String country) async {
    final response = await http.get(Uri.parse('$baseUrl?q=$city,$country&appid=$apiKey&units=metric'));

    if (response.statusCode == 200) {
      return jsonDecode(response.body);
    } else {
      throw Exception('Failed to get Data');
    }
  }
}