How can I get data using provider? - flutter

Question

I am implementing login with provider but I am not getting data on dashboard page.
Model Class
class LoginModel {
Data data;
int status;
String message;
LoginModel({this.data, this.status, this.message});
LoginModel.fromJson(Map<String, dynamic> json) {
data = json['data'] != null ? new Data.fromJson(json['data']) : null;
status = json['status'];
message = json['message'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
if (this.data != null) {
data['data'] = this.data.toJson();
}
data['status'] = this.status;
data['message'] = this.message;
return data;
}
}
class Data {
String customerId;
String customerMobileNo;
String customerToken;
String otp;
Data({this.customerId, this.customerMobileNo, this.customerToken, this.otp});
Data.fromJson(Map<String, dynamic> json) {
customerId = json['customerId'];
customerMobileNo = json['customerMobileNo'];
customerToken = json['customerToken'];
otp = json['otp'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['customerId'] = this.customerId;
data['customerMobileNo'] = this.customerMobileNo;
data['customerToken'] = this.customerToken;
data['otp'] = this.otp;
return data;
}
}
Provider Class
class AuthProvider extends ChangeNotifier {
Future<LoginModel> generateOTP(String mobileNumber) async {
var result;
Response response = await post(
AppUrl.login,
body: {
'mobileNo': mobileNumber,
},
);
if(response.statusCode==200) {
final responseData = json.decode(response.body);
var userData = responseData['data'];
print(responseData);
LoginModel authUser = LoginModel.fromJson(userData);
notifyListeners();
}
else {
print("Something went wrong");
}
return result;
}
}
Display Page
class Dashboard extends StatelessWidget {
#override
Widget build(BuildContext context) {
final userTest = Provider.of<AuthProvider>(context);
return Scaffold(
body: Center(
child: ListView(
shrinkWrap: true,
children: [
Text(userTest.authUser.data.customerToken),
],
),
),
);
}
Error
The following NoSuchMethodError was thrown while handling a gesture:
The getter 'customerToken' was called on null.
Receiver: null
Tried calling: customerToken
How can I access the property of LoginModel class. Can anyone solve my query please help me, I tried a lott but I can not get value.

Answer 1

You cannot notify your listeners with normal Future functions (though, I am not sure because you didn't provide the full code of your provider class). You will have to put your generateOTP() function in a changenotifier class that will help you to notify your listeners whenever required and make it scoped to your widget.
You are getting this error because you are not storing your token anywhere or you are not invoking your storage token before using it. So first, please try to store your token and invoke it before using it.

Answer 2

LoginModel authUser = LoginModel.fromJson(userData); you are initializing value to method variable LoginModel authUser not a class variable authUser try removing LoginModel from before 'authUser'.
In Dashboard you should also check for null value, you can do that like this userTest?.authUser?.data?.customerToken ?? ''