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I am trying to convert success JSON string to Object. May be I am not doing in proper manner But I have couple of question related to converting JSON to Object.
Also I am getting this exeption in Log.
NoSuchMethodError: Class '**_InternalLinkedHashMap<String, dynamic>' has no instance method 'cast' with matching arguments**.<br>
Receiver: _LinkedHashMap len:3
**Tried calling: cast<Map<String, dynamic>>()**
Should I need cast that data object in model too?
Which is the best and simple way to convert JSON to Object (SignUpResponse).
Its better to do with serialization ?
Response JSON :
"data": {
"_id": "5bd2a59f4c59de1ac517d7bf",
"email": "fjhsd@gmail.com",
"phoneNumber": "2417874147",
"isAddressApproved": 0,
"unitNumber": "144",
"streetAddress": "sdfsddsf",
"area": "asd",
"zipCode": "112233",
"totalOrder": 0,
"todayOrder": 0,
"isPauseDelivery": false,
"vacationStartDt": null,
"vacationEndDt": null,
"defaultLiter": 1
"message": "New User Created",
"error": false
SignUpResponse which was created by online tool.
class SignUpResponse {
Data data;
String message;
bool error;
SignUpResponse({this.data, this.message, this.error});
SignUpResponse.fromJson(Map<String, dynamic> json) {
data = json['data'] != null ? new Data.fromJson(json['data']) : null;
message = json['message'];
error = json['error'];
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
if (this.data != null) {
data['data'] = this.data.toJson();
data['message'] = this.message;
data['error'] = this.error;
return data;
class Data {
String sId;
String email;
String phoneNumber;
int isAddressApproved;
String unitNumber;
String streetAddress;
String area;
String zipCode;
int totalOrder;
int todayOrder;
bool isPauseDelivery;
Null vacationStartDt;
Null vacationEndDt;
int defaultLiter;
Data(
{this.sId,
this.email,
this.phoneNumber,
this.isAddressApproved,
this.unitNumber,
this.streetAddress,
this.area,
this.zipCode,
this.totalOrder,
this.todayOrder,
this.isPauseDelivery,
this.vacationStartDt,
this.vacationEndDt,
this.defaultLiter});
Data.fromJson(Map<String, dynamic> json) {
sId = json['_id'];
email = json['email'];
phoneNumber = json['phoneNumber'];
isAddressApproved = json['isAddressApproved'];
unitNumber = json['unitNumber'];
streetAddress = json['streetAddress'];
area = json['area'];
zipCode = json['zipCode'];
totalOrder = json['totalOrder'];
todayOrder = json['todayOrder'];
isPauseDelivery = json['isPauseDelivery'];
vacationStartDt = json['vacationStartDt'];
vacationEndDt = json['vacationEndDt'];
defaultLiter = json['defaultLiter'];
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['_id'] = this.sId;
data['email'] = this.email;
data['phoneNumber'] = this.phoneNumber;
data['isAddressApproved'] = this.isAddressApproved;
data['unitNumber'] = this.unitNumber;
data['streetAddress'] = this.streetAddress;
data['area'] = this.area;
data['zipCode'] = this.zipCode;
data['totalOrder'] = this.totalOrder;
data['todayOrder'] = this.todayOrder;
data['isPauseDelivery'] = this.isPauseDelivery;
data['vacationStartDt'] = this.vacationStartDt;
data['vacationEndDt'] = this.vacationEndDt;
data['defaultLiter'] = this.defaultLiter;
return data;
Calling REST POST API
void postCallSignUp(BuildContext context, var body) {
// This Function will check Internet is available or not.
Utils.checkConnection().then((connectionResult) {
if (connectionResult) {
http.post(Constants.BASE_URL + Constants.CREATE_USER,
body: body,
headers: {
"Accept": "application/json",
"content-type": "application/json"
}).then((http.Response response) {
final String res = response.body;
final int statusCode = response.statusCode;
if (statusCode < 200 || statusCode > 400 || json == null) {
_onFailureResponse(new Exception("Error while fetching data"));
} else {
//Parsing json response to particular Object.
print(json.decode(res));
// Unable to cast json here...
final parsed = json.decode(res).cast<Map<String, dynamic>>();
parsed.map<SignUpResponse>((json) => SignUpResponse.fromJson(json));
SignUpResponse signUpResponse = parsed.map<SignUpResponse>((json) => SignUpResponse.fromJson(json));
_onSuccessResponse(signUpResponse);
} else {
_onNoInternetConnection();
Utils.showAlert(context, "Alert", "Internet is not connected.", () {
Navigator.pop(context);
Unable to understand what is happening here ? Why we have to do so much for convert our json to particular object ?
Don't need to use cast, you can parse directly to a Map
final Map parsed = json.decode(res);
After you have a map you can use that data to convert into your Object.
final signUp = SignUpResponse.fromJson(parsed);
And if you want to parse an array of objects, you could do something like this:
//assuming this json returns an array of signupresponse objects
final List parsedList = json.decode(res);
List<SignUpResponse> list = parsedList.map((val) => SignUpResponse.fromJson(val)).toList();
–
country({this.id,this.name,this.currency});
factory country.fromJson(Map<String, dynamic> parsedJson){
return country(
id: parsedJson['id'].toString(),
name : parsedJson['name'].toString(),
currency: parsedJson['currency'].toString()
API CALL :
await http.post("http://calikidsmap.com/test.php").then((response){
var ddd=jsonDecode(response.body);
Country_object_list = (ddd as List)
.map((data) => new country.fromJson(data))
.toList();
Here is a basic answer for this if you want to access your information after the request with no extra steps.
Map<String, dynamic> data = jsonDecode(response.body);
String token = data["data"]["access_token"];
the structure of the object from the request was like this:
"success":1,
"error":[],
"data": {
"access_token":"13d2ec9d1094903b1e81de8af059233e9f36ec4d",
"expires_in":2628000,
"token_type":"Bearer"
Same answer but, what happens when you have nested JsonObjects?
Easy:
Given a jsonResponse like this:
"id": 1,
"type": 15,
"innerClass": {
"id": 1,
"type": "testing"
This is an example of how the code looks like:
class MainClass {
int id = 0;
int version = 0;
InnerClass innerClass;
MainClass (
this.id,
this.version,
this.innerClass
//Create the same factory converter, but using another inner factory 'fromJson' converter
//for the inner class object (InnerClass.fromJson(json['inner_class']))
factory MainClass.fromJson(dynamic json) {
return MainClass(
json['id'] as int, // << put your json response keys instead.
json['version'] as int,
InnerClass.fromJson(json['innerClass']) // << this one
Then, repeat the same strategy but for the inner class object:
class InnerClass {
int id = 0;
String type = 'testing_type';
InnerClass (
this.id,
this.type
factory InnerClass.fromJson(dynamic json) {
return InnerClass(
json['id'] as int,
json['type'] as String
Finally, you could cosume that, in another part of you project like this:
try {
mainClassDartObject = MainClass.fromJson(response.body);
} catch (e) {
print(e);
# Your other dev_dependencies here
build_runner: <latest_version>
json_serializable: <latest_version>
Object class.
import 'package:json_annotation/json_annotation.dart';
part 'user.g.dart'; //"user" is your dart file name
/// JSON serialization logic to be generated.
@JsonSerializable()
class User {
User(this.name, this.email);
String name;
String email;
factory User.fromJson(Map<String, dynamic> json) => _$UserFromJson(json);
Map<String, dynamic> toJson() => _$UserToJson(this);
And run this in Terminal of Android Studio.
flutter pub run build_runner build
Now convert like this:
Map results = json.decode(response.body);
User user = User.fromJson(results);
Source: https://flutter.dev/docs/development/data-and-backend/json
This worked for me using http: ^0.13.3 library
LoginResponseModel posts = LoginResponseModel();
final response = await http.post(
Uri.parse(URL HERE),
headers: {
"Content-Type": "application/x-www-form-urlencoded",
encoding: Encoding.getByName('utf-8'),
body: {
"param1": value1,
"param2": value2,
"param3": value3,
"param4": value4
if (response.statusCode == 200) {
// If the server did return a 200 OK response,
// then parse the JSON.
final Map<String, dynamic> parsed = json.decode(response.body);
posts = LoginResponseModel.fromJson(parsed);
} else {
// If the server did not return a 200 OK response,
// then throw an exception.
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