Flutter json decode

Question

I have a question about json in flutter. How can I make an api request.

there is an approximate data that is in the template. but I need to take it through url. I tried many examples that are here, but I still haven't figured it out.

Posts are taken for both Russian and English.

    class DummyPosts{
    
      static final Map<String, List<Post>> posts = {
        'ru': _ru,
        "en": _en,
      };
    
      static final List<Post> _ru = [
        Post(
          id: 1,
          title: 'Apple expands renewable energy footprint in Europe',
          thumbnail:
          'https://www.apple.com/newsroom/images/values/environment/apple_eu-renewable-energy-expansion_wind-farm_09012020_big.jpg.large_2x.jpg',
          excerpt: 'World’s largest onshore wind turbines in Denmark and new clean energy efforts in Germany advance Apple’s new 2030 carbon neutral goal',
          category: 'Tech',
          views: 456,
          comments: 23,
          htmlContent: '<p>Today Apple announced it will invest in the construction of two of the world’s largest onshore wind turbines, a source of clean, renewable energy that will bring its supply chain and products one step closer to carbon neutrality. Located near the Danish town of Esbjerg, the 200-meter-tall turbines are expected to produce 62 gigawatt hours each year — enough to power almost 20,000 homes — and will act as a test site for powerful offshore wind turbines. The power produced at Esbjerg will support Apple’s data center in Viborg, with all surplus energy going into the Danish grid.</p>',
          tags: [
            Tag(id: 1, name: 'Post'),
            Tag(id: 2, name: 'News'),
            Tag(id: 3, name: 'Tech'),
            Tag(id: 4, name: 'Apple'),
          ],
          createdAt: DateTime.now().subtract(Duration(days: 900)),
        ),
];

  static final List<Post> _en = [
    Post(
      id: 1,
      title: 'Apple expands renewable energy footprint in Europe',
      thumbnail:
          'https://www.apple.com/newsroom/images/values/environment/apple_eu-renewable-energy-expansion_wind-farm_09012020_big.jpg.large_2x.jpg',
      excerpt: 'World’s largest onshore wind turbines in Denmark and new clean energy efforts in Germany advance Apple’s new 2030 carbon neutral goal',
      category: 'Tech',
      views: 456,
      comments: 23,
      htmlContent: '<p>Today Apple announced it will invest in the construction of two of the world’s largest onshore wind turbines, a source of clean, renewable energy that will bring its supply chain and products one step closer to carbon neutrality. Located near the Danish town of Esbjerg, the 200-meter-tall turbines are expected to produce 62 gigawatt hours each year — enough to power almost 20,000 homes — and will act as a test site for powerful offshore wind turbines. The power produced at Esbjerg will support Apple’s data center in Viborg, with all surplus energy going into the Danish grid.</p>',
      tags: [
        Tag(id: 1, name: 'Post'),
        Tag(id: 2, name: 'News'),
        Tag(id: 3, name: 'Tech'),
        Tag(id: 4, name: 'Apple'),
      ],
      createdAt: DateTime.now().subtract(Duration(days: 900)),
    ),
];

Model

class Post{
  int id;
  String title;
  String excerpt;
  String thumbnail;
  String category;
  int views;
  int comments;
  String htmlContent;
  List<Tag> tags;
  DateTime createdAt;

  Post({
    this.id,
    this.title,
    this.excerpt,
    this.thumbnail,
    this.category,
    this.views,
    this.comments,
    this.htmlContent,
    this.tags,
    this.createdAt,
  });


}

Sorry for my English.

rostIvan · Accepted Answer · 2021-05-09 12:06:08Z

2

1. Prerequisites

Add http package

dependencies:
  http: <latest_version>

Import the http package

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

Add in your AndroidManifest.xml the Internet permission

<uses-permission android:name="android.permission.INTERNET" />

2. Make a network request

Future<http.Response> fetchPosts(String lang) {
  return http.get(Uri.https('api-url.com', 'posts', {'lang': lang}));
}

3. Convert to object

class Post{
  int id;
  String title;
  String excerpt;
  String thumbnail;
  String category;
  int views;
  int comments;
  String htmlContent;
  List<Tag> tags;
  DateTime createdAt;

  Post({
    this.id,
    this.title,
    this.excerpt,
    this.thumbnail,
    this.category,
    this.views,
    this.comments,
    this.htmlContent,
    this.tags,
    this.createdAt,
  });
  
  factory Post.fromJson(Map<String, dynamic> json) {
    return Post(
      id: json['id'],
      title: json['title'],
      // ... and other attr
    );
  }
}

final response1 = await fetchPosts("en");
final response2 = await fetchPosts("ru");
final List<Post> enPosts = response1.body.map((i) => Post.fromJson(i)).toList();
final List<Post> ruPosts = response2.body.map((i) => Post.fromJson(i)).toList();

UPD:

I would add something like this in your case

Future<Map<String, List<Post>>> getPosts() async {
    final response1 = await fetchPosts("en");
    final response2 = await fetchPosts("ru");
    final List<Post> enPosts = response1.body.map((i) => Post.fromJson(i)).toList();
    final List<Post> ruPosts = response2.body.map((i) => Post.fromJson(i)).toList();
    return {
      "en": enPosts,
      'ru': ruPosts,
    };
  }

Instead of

static final Map<String, List<Post>> posts = {
    'ru': _ru,
    "en": _en,
  };

edited May 9, 2021 at 12:06

answered May 3, 2021 at 15:34

rostIvan

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2 Comments

Ильяс Бадыганов Over a year ago

thank you very much for the help. But could you please explain where I should insert this, tk. I do not quite understand. I'm just learning flutter

Ильяс Бадыганов Over a year ago

@rostvlan I can post a template. could you help with 1 example, post. drive.google.com/file/d/1-xuqfxZO0lXzJTEWwiPczieq3AUbLPIR/…

Ian · Accepted Answer · 2021-05-03 15:58:41Z

0

May I suggest you check out using chopper and json annotation to manage your requests? ResoCoder has an excellent series of three videos and accompanything posts over at https://resocoder.com/2019/06/19/chopper-retrofit-for-flutter-basics/ that will guide you through the process.

It's a little bit more work to get it started but I think it will save you effort in the long term.

answered May 3, 2021 at 15:58

Ian

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