Null value comes from singleton structure - flutter

Question

I am developing an application with flutter. I set up a singleton structure to access the data in shared preferences. I made a password change area in the settings section of the application. And I wrote the service with node js, everything works fine, but the email value is null.
how can i fix the problem
data_store (singleton)
class DataStore {
static DataStore? _dataStore;
static DataStore? getInstance() {
if (_dataStore == null) {
// keep local instance till it is fully initialized.
var data = DataStore._();
_dataStore = data;
}
return _dataStore;
}
DataStore._();
UserModel user = UserModel();
bool? putUser(UserModel user) {
this.user = user;
return null;
}
UserModel? getUser() {
return user;
}
}
change password page
import 'package:flutter/material.dart';
import 'package:meetdy/Constants/Utils/app_shared_preferences.dart';
import 'package:meetdy/Constants/colors.dart';
import 'package:meetdy/Constants/utils/data_store.dart';
import 'package:meetdy/Models/auth_models/change_passsword_models/change_password_req_model.dart';
import 'package:meetdy/Models/auth_models/user_model.dart';
import 'package:meetdy/Services/auth_services/change_password_services/change_password_services.dart';
import 'package:provider/provider.dart';
import 'package:sizer/sizer.dart';
class ChangePasswordScreen extends StatefulWidget {
const ChangePasswordScreen({Key? key}) : super(key: key);
#override
State<ChangePasswordScreen> createState() => _ChangePasswordScreenState();
}
class _ChangePasswordScreenState extends State<ChangePasswordScreen> {
late Size size = MediaQuery.of(context).size;
bool _isObscure = true;
bool isLoading = false;
final _formKey = GlobalKey<FormState>();
final _passwordController = TextEditingController();
final DataStore? _dataStore = DataStore.getInstance();
UserModel? user;
#override
void initState() {
user = _dataStore?.getUser();
super.initState();
}
#override
Widget build(BuildContext context) {
return SafeArea(
child: GestureDetector(
onTap: () {
FocusManager.instance.primaryFocus?.unfocus();
},
child: Scaffold(
appBar: buildAppBar(context),
body: Padding(
padding: EdgeInsets.symmetric(horizontal: 3.h, vertical: 1.h),
child: Column(
children: [
SizedBox(height: 2.h),
// Login TextFields
Padding(
padding: const EdgeInsets.all(10.0),
child: Column(
children: [
Form(
key: _formKey,
child: TextFormField(
obscureText: _isObscure,
controller: _passwordController,
cursorColor: AppColors.lightBlack,
decoration: InputDecoration(
suffixIcon: IconButton(
icon: Icon(
_isObscure
? Icons.visibility
: Icons.visibility_off,
color: Colors.grey,
),
onPressed: () {
setState(() {
_isObscure = !_isObscure;
});
}),
focusedBorder: InputBorder.none,
enabledBorder: InputBorder.none,
disabledBorder: InputBorder.none,
labelText: 'Password',
labelStyle: TextStyle(
color: AppColors.lightBlack,
),
),
validator: (value) {
if (value!.isEmpty) {
return 'Required';
} else if (value.length < 6) {
return 'Password must be at least 6 characters';
}
return null;
},
onSaved: (value) {
_passwordController.text = value!;
},
),
),
SizedBox(height: 4.h),
Consumer<ChangePasswordService>(
builder: (context, provider, child) {
return Row(
mainAxisAlignment: MainAxisAlignment.end,
children: [
Text(
"Update",
style: TextStyle(
fontSize: 22.sp,
color: AppColors.black,
fontWeight: FontWeight.w300),
),
Padding(
padding:
EdgeInsets.symmetric(horizontal: 1.0.h)),
isLoading
? CircularProgressIndicator(
color: AppColors.orange)
: FloatingActionButton(
backgroundColor: AppColors.orange,
onPressed: () async {
final form = _formKey.currentState;
if (!form!.validate()) {
return;
}
setState(() {
isLoading = true;
});
String password =
_passwordController.text.trim();
String? email = user!.email;
ChangePasswordReqModel passwordData =
ChangePasswordReqModel(
email: email,
password: password);
var newPassword = await provider
.changePassword(passwordData);
setState(() {
isLoading = false;
});
if (newPassword?.error != null) {
var snackBar = SnackBar(
content: Text(
newPassword?.error?.message ??
""),
duration: Duration(seconds: 2),
behavior: SnackBarBehavior.floating,
shape: RoundedRectangleBorder(
borderRadius:
BorderRadius.circular(20)),
clipBehavior: Clip.hardEdge,
);
// ignore: use_build_context_synchronously
ScaffoldMessenger.of(context)
.showSnackBar(snackBar);
} else {
var snackBar = SnackBar(
content: Text(
"Your password has been successfully changed"),
duration: Duration(seconds: 2),
behavior: SnackBarBehavior.floating,
shape: RoundedRectangleBorder(
borderRadius:
BorderRadius.circular(20)),
clipBehavior: Clip.hardEdge,
);
// ignore: use_build_context_synchronously
ScaffoldMessenger.of(context)
.showSnackBar(snackBar);
}
_passwordController.clear();
},
child: Icon(
Icons.keyboard_arrow_right_sharp))
]);
})
],
),
),
],
),
),
),
),
);
}
AppBar buildAppBar(BuildContext context) {
return AppBar(
backgroundColor: Colors.transparent,
elevation: 0,
centerTitle: true,
title: Text(
"Change Password",
style: TextStyle(
color: AppColors.lightBlack,
),
),
leading: IconButton(
icon: Icon(Icons.arrow_back, color: AppColors.lightBlack),
onPressed: () => Navigator.of(context).pop(),
),
);
}
}