Question 75962 in Flutter Question posted in
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How to fix _CastError (Null check operator used on a null value) -Flutter (Dart)

I am trying to get the user’s profile picture, name and email but I keep on getting the _CastError (Null check operator used on a null value) error. This is where I get my error:

final user = FirebaseAuth.instance.currentUser!;//at the end is where the error is (the '!')

Code:

        Column(
          children: [
            CircleAvatar(
              radius: 52,
            backgroundImage: NetworkImage(user.photoURL!),
            ),
            const SizedBox(
              height: 8,
            ),
            Text(
              user.displayName!,
              style: titleStyle,
            ),
            const SizedBox(
              height: 8,
            ),
            Text(
              user.email!,
              style: titleStyle,
            ),
          ],
        ),

I’ve tried moving the ! around but it just throws the error somewhere else then. I’ve tried implementing ??/? on some places but to also no help.

Tags:

3

Answers


  1. 0

    Because currentUser is null, you need to accept null and handle it properly like.

    final user = FirebaseAuth.instance.currentUser;
// now `user` can accept null and the title error will be gone

    Next thing comes when you are using it.

    if(user?.photoURL!=null) CircleAvatar(....

    Find more about null-safety.

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  2. 0

    After watching some videos I figured that it was just a wrong approach and there are better and easier ways of doing it.

    final controller = Get.put(LoginController());
final _googleSignin = GoogleSignIn();
var googleAccount = Rx<GoogleSignInAccount?>(null);

    login() async {
    googleAccount.value = await _googleSignin.signIn();
  }

    Column(
          children: [
            CircleAvatar(
              radius: 52,
              backgroundImage:
                  NetworkImage(controller.googleAccount.value?.photoUrl ?? ''),
            ),
            const SizedBox(
              height: 8,
            ),
            Text(
              controller.googleAccount.value?.displayName ?? '',
              style: subHeadingStyle,
            ),
            const SizedBox(
              height: 8,
            ),
            Text(
              controller.googleAccount.value?.email ?? '',
              style: subHeadingStyle,
            ),
            const SizedBox(
              height: 20,
            )
          ],
        ),
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  3. 0

    // 1. Check if the variable is null before using it:

    if (variable != null) { // use variable safely } else { // handle null case }

    // 2. Use the null-aware operator (?.) instead of the null check operator (!) to avoid the error altogether:

    variable?.doSomething();

    // 3. Use the null-coalescing operator (??) to provide a default value when the variable is null:

    final value = variable ?? defaultValue;

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