CODEWITHSUNDEEP
dartflutter
Vipin Dubey
Vipin Dubey

Reputation: 592

Parsing Json in flutter

I am learning flutter and trying to parse a json which is array or json objects like this.

[
  {
    "albumId": 1,
    "id": 1,
    "title": "accusamus beatae ad facilis cum similique qui sunt",
    "url": "https://via.placeholder.com/600/92c952",
    "thumbnailUrl": "https://via.placeholder.com/150/92c952"
  },
  {
    "albumId": 1,
    "id": 2,
    "title": "reprehenderit est deserunt velit ipsam",
    "url": "https://via.placeholder.com/600/771796",
    "thumbnailUrl": "https://via.placeholder.com/150/771796"
  },]

And here is my fetch function which fetches this data from server.

 fetch() async{

   var client = new http.Client();
  try {
  var uriResponse = await 
  client.get('https://jsonplaceholder.typicode.com/photos');
  if(uriResponse.statusCode == 200){

  var data = json.decode(uriResponse.body);//data is array of objects
  List<Photo> pics= data.map((Map<String,dynamic> model)=> Photo.fromJson(model)).toList();
  setState(() {
    photos = data;
    _isLoading = false;
  });
}
  } finally {
client.close();
  }
}

But the line ;

List<Photo> pics= data.map((Map<String,dynamic> model)=> Photo.fromJson(model)).toList();

gives me error that:

ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: type '(Map<String, dynamic>, dynamic) => Photo' is not a subtype of type '(dynamic) => dynamic' of 'f'

Here is my Photo PODO class.

  class Photo {
  final int id;
  final String title;
  final String url;
  final String thumbnailUrl;

  Photo({this.id, this.title,this.url, this.thumbnailUrl});

  factory Photo.fromJson(Map<String, dynamic> json) {
    return Photo(
      id: json['id'] as int,
      title: json['title'] as String,
      thumbnailUrl: json['thumbnailUrl'] as String,
      url: json['url'] as String,
    );
  }
}

What i am doing wrong in the above code? Thanx in advance !

Upvotes: 2

Views: 2443

Answers (4)

Preeth Prathapan
Preeth Prathapan

Reputation: 66

In my project I have done like this and its working

pics = (data as List).map((model) => Photo.fromJson(model)).toList();

Upvotes: 1

Lukas Kirner
Lukas Kirner

Reputation: 4319

You can use quicktype it lets you copy in your JSON string and generates the Dart Objects

Upvotes: 2

youssef ali
youssef ali

Reputation: 426

try this if it didnt work make sure to print the the response body 

Iterable<dynamic> l = json.decode(uriResponse.body);
List<Post> posts = l.map((model) => Post.fromJson(model)).toList();

Upvotes: 0

Mangaldeep Pannu
Mangaldeep Pannu

Reputation: 3987

Try using

pics = data.map((i)=>Photo.fromJson(i)).toList();

You are receiving an json array and not json object from server

Upvotes: 0

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