Question 77159 in Flutter Question posted in
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FlutterFire Auth verifyPhoneNumber method isn't being waited on

I’m trying to create an auth service and I want to return the verificationId from the custom method. However, calling this method throws the null check exception because it doesn’t wait for the Future to complete before returning.

Future<String> sendPhoneVerification({
    required String phoneNumber,
  }) async {
    String? result;
    await FirebaseAuth.instance.verifyPhoneNumber(
      phoneNumber: '+1$phoneNumber',
      verificationCompleted: (
        PhoneAuthCredential credential,
      ) {
        result = credential.verificationId;
      },
      verificationFailed: (e) {
        if (e.code == 'invalid-phone-number') {
          throw InvalidPhoneNumberAuthException();
        } else if (e.code == 'too-many-requests') {
          throw TooManyRequestsAuthException();
        } else {
          throw GenericAuthException();
        }
      },
      codeSent: (verificationId, resendToken) {
        print('ver_id $verificationId');
        result = verificationId;
      },
      codeAutoRetrievalTimeout: (_) {},
    );
    print('This is the result $result');
    return result!;
  }

Here is the output in the terminal.

flutter: This is the result null
flutter: ver_id <ver_id>
Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    I figured out the solution. I found out the verifyPhoneNumber method returns a future but the implementation doesn't await that async call. I used a [completer][1] to return a future.

    Future<String> sendPhoneVerification({required String phoneNumber}) async {
    Completer<String> result = Completer();
    await FirebaseAuth.instance.verifyPhoneNumber(
      phoneNumber: '+1$phoneNumber',
      verificationCompleted: (
        PhoneAuthCredential credential,
      ) {
        result.complete(credential.verificationId);
      },
      verificationFailed: (e) {
        if (e.code == 'invalid-phone-number') {
          result.completeError(InvalidPhoneNumberAuthException());
        } else if (e.code == 'too-many-requests') {
          result.completeError(TooManyRequestsAuthException());
        } else {
          result.completeError(GenericAuthException());
        }
      },
      codeSent: (verificationId, resendToken) {
        result.complete(verificationId);
      },
      codeAutoRetrievalTimeout: (_) {},
    );
    return result.future;
  }

  2. 0

    Please add this property timeout: const Duration(seconds: 60), in the verifyPhoneNumber() method

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