how to convert json string to json object in dart flutter?

You have to use json.decode. It takes in a json object and let you handle the nested key value pairs. I'll write you an example

import 'dart:convert';// actual data sent is {success: true, data:{token:'token'}}final response = await client.post(url, body: reqBody);// Notice how you have to call body from the response if you are using http to retrieve jsonfinal body = json.decode(response.body);// This is how you get success value out of the actual jsonif (body['success']) {  //Token is nested inside data field so it goes one deeper.  final String token = body['data']['token'];  return {"success": true, "token": token};}

Assume that we have a simple JSON structure like this:

{  "name": "bezkoder",  "age": 30}

We will create a Dart class named User with fields: name & age.

class User {  String name;  int age;  User(this.name, this.age);  factory User.fromJson(dynamic json) {    return User(json['name'] as String, json['age'] as int);  }  @override  String toString() {    return '{ ${this.name}, ${this.age} }';  }}

You can see factory User.fromJson() method in the code above. It parses a dynamic object into User object. So how to get dynamic object from a JSON string?

We use dart:convert library’s built-in jsonDecode() function.

import 'dart:convert';main() {  String objText = '{"name": "bezkoder", "age": 30}';  User user = User.fromJson(jsonDecode(objText));  print(user);

The result will look like this.

{ bezkoder, 30 }

Ref : Dart/Flutter parse JSON string into Object

You must need to use this sometimes

Map<String, dynamic> toJson() {  return {    jsonEncode("phone"): jsonEncode(numberPhone),    jsonEncode("country"): jsonEncode(country), };}

This code give you a like string {"numberPhone":"+225657869", "country":"CI"}. So it's easy to decode it's after like that

     json.decode({"numberPhone":"+22565786589", "country":"CI"})