I am using the dart package json_serializable for json serialization. Looking at the flutter documentation it shows how to deserialize a single object as follow:
Future<Post> fetchPost() async {
final response =
await http.get('https://jsonplaceholder.typicode.com/posts/1');
if (response.statusCode == 200) {
// If the call to the server was successful, parse the JSON
return Post.fromJson(json.decode(response.body));
} else {
// If that call was not successful, throw an error.
throw Exception('Failed to load post');
}
}
However, I am not familiar enough with dart to figure out how to do the same for a list of items instead of a single instance.
Well, your service would handle either the response body being a map, or a list of maps accordingly. Based on the code you have, you are accounting for 1 item.
If the response body is an iterable, then you need to parse and walk accordingly, if i am understanding your question correctly.
Example:
Iterable l = json.decode(response.body);
List<Post> posts = l.map((Map model)=> Post.fromJson(model)).toList();
where posts is a LIST of posts.
EDIT: I wanted to add a note of clarity here. The purpose here is that you decode the response returned. The next step, is to turn that iterable of json objects into an instance of your object. This is done by creating fromJson methods in your class to properly take json and implement it accordingly. Below is a sample implementation.
class Post {
// Other functions and properties relevant to the class
// ......
/// Json is a Map<dynamic,dynamic> if i recall correctly.
static fromJson(json): Post {
Post p = new Post()
p.name = ...
return p
}
}
I am a bit abstracted from Dart these days in favor of a better utility for the tasks needing accomplished. So my syntax is likely off just a little, but this is Pseudocode.
Just another example on JSON Parsing for further clarification.
Let say we want to parse items array in our JSON Object.
factory YoutubeResponse.fromJSON(Map<String, dynamic> YoutubeResponseJson)
{
// Below 2 line code is parsing JSON Array of items in our JSON Object (YouttubeResponse)
var list = YoutubeResponseJson['items'] as List;
List<Item> itemsList = list.map((i) => Item.fromJSON(i)).toList();
return new YoutubeResponse(
kind: YoutubeResponseJson['kind'],
etag: YoutubeResponseJson['etag'],
nextPageToken: YoutubeResponseJson['nextPageToken'],
regionCode: YoutubeResponseJson['regionCode'],
mPageInfo: pageInfo.fromJSON(YoutubeResponseJson['pageInfo']),
// Here we are returning parsed JSON Array.
items: itemsList);
}
I always use this way with no problem;
List<MyModel> myModels;
var response = await http.get("myUrl");
myModels=(json.decode(response.body) as List).map((i) =>
MyModel.fromJson(i)).toList();
First, create a class that matches your json data, in my case, I create (generate) class named Img:
import 'dart:convert';
Img imgFromJson(String str) => Img.fromJson(json.decode(str));
String imgToJson(Img data) => json.encode(data.toJson());
class Img {
String id;
String img;
dynamic decreption;
Img({
this.id,
this.img,
this.decreption,
});
factory Img.fromJson(Map<String, dynamic> json) => Img(
id: json["id"],
img: json["img"],
decreption: json["decreption"],
);
Map<String, dynamic> toJson() => {
"id": id,
"img": img,
"decreption": decreption,
};
}
PS. You can use app.quicktype.io to generate your json data class in dart.
then send you post/get to your server:
Future<List<Img>> _getimages() async {
var response = await http.get("http://192.168.115.2/flutter/get_images.php");
var rb = response.body;
// store json data into list
var list = json.decode(rb) as List;
// iterate over the list and map each object in list to Img by calling Img.fromJson
List<Img> imgs = list.map((i)=>Img.fromJson(i)).toList();
print(imgs.runtimeType); //returns List<Img>
print(imgs[0].runtimeType); //returns Img
return imgs;
}
for more info this is an article about Parsing complex JSON in Flutter
You can also Do it like
List< Item > itemsList= List< Item >.from(parsedListJson.map((i) => Item.fromJson(i)));
follow this step
step 1-> create model class (name as LoginResponce ) click here to convert json to dart .
step 2-> LoginResponce loginResponce=LoginResponce.fromJson(json.decode(response.body));
step 3 -> now you get your data in instence of model (as loginResponce ).
