Flutter - user model is NULL even after binding it using bindStream - flutter

Question

I am trying to add a shopping cart functionality to my app wherein the UserModel contains fields name,email,uid and cart. I have created an AuthController extends GetxController where I have created userModel isntance and then in setInitialScreen function I am binding the userModel to a function "listenToUser()" which is a Stream and recieves snapshot from firestore and maps it to the userModel. But on printing the userModel I see null being printed in the console meaning the data is not getting binded which is causing problems as i can't access the cart stored in the userModel.
Edit: I saw that I need to attach obs to userModel like: Rx<model.User>? userModel = model.User().obs; but there's a problem that all the fields in this model are required and how can i pass these field values when they have not yet been intialized.
Console output:
AuthController code
class AuthController extends GetxController {
static AuthController instance = Get.find();
late Rx<User?> _user;
Rx<model.User>? userModel;
#override
void onReady() {
super.onReady();
_user = Rx<User?>(firebaseAuth.currentUser);
_user.bindStream(firebaseAuth.authStateChanges());
ever(_user, _setInitialScreen);
}
_setInitialScreen(User? user) {
if (user == null) {
Get.offAll(() => LoginScreen());
} else {
userModel?.bindStream(listenToUser());
Get.offAll(() => const HomeScreen());
print(userModel); // PRINTING USER MODEL TO SEE IF ITS NULL
// userModel?.bindStream(listenToUser());
}
}
// registering the user
void registerUser(String username, String email, String password) async {
try {
if (username.isNotEmpty && email.isNotEmpty && password.isNotEmpty) {
// save our user to our auth and firebase firestore
UserCredential cred = await firebaseAuth.createUserWithEmailAndPassword(
email: email,
password: password,
);
model.User user = model.User(
name: username, email: email, uid: cred.user!.uid, cart: []);
await firestore
.collection('users')
.doc(cred.user!.uid)
.set(user.toJson());
} else {
Get.snackbar(
'Error Creating Account',
'Please enter all the fields',
);
}
} catch (e) {
Get.snackbar(
'Error Creating Account',
e.toString(),
);
}
}
void loginUser(String email, String password) async {
try {
if (email.isNotEmpty && password.isNotEmpty) {
await firebaseAuth.signInWithEmailAndPassword(
email: email, password: password);
print('log success');
} else {
Get.snackbar(
'Error Logging in',
'Please enter all the fields',
);
}
} catch (e) {
Get.snackbar(
'Error Logging in',
e.toString(),
);
}
}
updateUserData(Map<String, dynamic> data) {
print("UPDATED");
firestore.collection('users').doc(_user.value?.uid).update(data);
}
Stream<model.User> listenToUser() => firestore
.collection('users')
.doc(_user.value?.uid)
.snapshots()
.map((snapshot) => model.User.fromSnap(snapshot));
}
User Model code:
class User {
// static const UID = "uid";
// static const NAME = "name";
// static const EMAIL = "email";
String uid;
String name;
String email;
List<CartItemModel> cart;
User(
{required this.name,
required this.email,
required this.uid,
required this.cart});
Map<String, dynamic> toJson() =>
{"name": name, "email": email, "uid": uid, "cart": cart};
// static User fromSnap(DocumentSnapshot snap) {
static User fromSnap(DocumentSnapshot snap) {
var snapshot = snap.data() as Map<String, dynamic>;
return User(
name: snapshot['name'],
email: snapshot['email'],
uid: snapshot['uid'],
cart: _convertCartItems(snapshot['cart'] ?? []));
}
// List<CartItemModel> _convertCartItems(List cartFromDb) {
static List<CartItemModel> _convertCartItems(List cartFromDb) {
List<CartItemModel> _result = [];
// logger.i(cartFromDb.lengt);
print(cartFromDb.length);
cartFromDb.forEach((element) {
_result.add(CartItemModel.fromMap(element));
});
return _result;
}
}
Also I referred this github for shopping cart functionality but I have made some changes to make it null safe: cart functionality github

Answer 1

Use Rxn<T>() for nullable rx:
final _user = Rxn<User>();
Then on onInit():
_user.bindStream(firebaseAuth.authStateChanges());