Hi Guys I am getting this error when trying to connect API's in flutter, I followed a tutorial but when trying to connect the newsapi I started getting this error " a value type "post" can't be assigned to a variable of the type 'List?'" Does anyone know how I can fix this?

Here is the services file

import 'package:new_cdsc/Model/post.dart';
import 'package:http/http.dart' as http;

class RemoteService {
  Future<Post?> getPosts() async {
    var client = http.Client();
    var uri = Uri.parse(
        'https://newsapi.org/v2/top-headlines?country=us&category=business&apiKey=a04fc11949fc4633aa00fb01f37957e7');
    var response = await client.get(uri);
    if (response.statusCode == 200) {
      var json = response.body;
      postFromJson(json);
      return postFromJson(json);
    }
  }
}

Here is the section of code where I am getting the error in my mainpage file

class _NewsState extends State<News> {
  late Future<Post?> _newsModel;
  List<Post>? posts;
  var isLoaded = false;


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




getData() async {
  posts = await RemoteService().getPosts();//error here
  if (posts != null) {
    setState(() {
      isLoaded = true;
    });
  }
}

CodePudding user response：

Since you haven't posted implementation of the postsFromJson(json) function, I am assuming the error (most likely) lies within. API returns a response of the following structure:

{
  "status": "ok",
  "totalResults": 70,
  "articles": [...]
}

So, make sure that within your postsFromJson(json) function, you are accessing the articles list properly. There are 2 ways to do this:

1. Directly pass the articles list to the postsFromJson() function.

if (response.statusCode == 200) {
  var json = response.body['articles'];
  return postFromJson(json);
}

2. Changing the structure of postsFromJson() function.

Map<String, dynamic> postsFromJson(Map<String, dynamic> json) {
  final totalArticles = json['totalResults'];
  final articles = json['articles'];

  // Use articles.
}

As a side note, please make sure not to include API keys or other sensitive data with question. In such scenarios, try to post a rough structure of the response you are dealing with.

CodePudding user response：

It looks like RemoteService().getPosts() returns a list, but you are assigning this to post which has a type List<Post>?. To fix this, cast RemoteService().getPosts() to a List<Post>? by calling

posts = await RemoteService().getPosts() as List<Post>;

If you're sure it returns a List of Post data types.