The argument type 'String?' cant be assigned to the parameter type 'String'. I a-CodePudding

UserCredential result= await _firebaseAuth.signInWithCredential(credential);

User? userDetails = result.user;

if(result!= null)
{
    SharedPreferenceHelper().saveUserEmail(userDetails.email);
    SharedPreferenceHelper().saveUserId(userDetails.uid);
    SharedPreferenceHelper().saveDisplayName(userDetails.displayName);
    SharedPreferenceHelper().saveUserProfileUrl(userDetails.photoURL);
}

This was my code, how can I reslove it?

I tried replacing '.' with '?.' and '!.' however it is not working

CodePudding user response：

Try to handle with the null operator and give some default value if they are null.

  UserCredential result= await _firebaseAuth.signInWithCredential(credential);
    
    User? userDetails = result.user;
    
    if(result!= null)
    {
        SharedPreferenceHelper().saveUserEmail(userDetails?.email??'');
        SharedPreferenceHelper().saveUserId(userDetails?.uid??'');
        SharedPreferenceHelper().saveDisplayName(userDetails?.displayName??'');
        SharedPreferenceHelper().saveUserProfileUrl(userDetails?.photoURL??'');
    }

CodePudding user response：

if the value of userDetails.email, userDetails.uid,userDetails.displayName etc is null try this

SharedPreferenceHelper().saveUserEmail(userDetails.email!);
SharedPreferenceHelper().saveUserId(userDetails.uid!);
SharedPreferenceHelper().saveDisplayName(userDetails.displayName!);
SharedPreferenceHelper().saveUserProfileUrl(userDetails.photoURL!);

it will solve your problem if not then let me know

CodePudding user response：

Explanation:

This is happening because you have declared userDetails as User? which means userDetails can be null but saveUserEmail() takes in type of String which cannot be null

Try with

// When you are sure that userDetails can never be null
SharedPreferenceHelper().saveUserEmail(userDetails.email!);

// When you want to store '' if the email is null
SharedPreferenceHelper().saveUserEmail(userDetails?.email ?? '');

User userDetails; // This option here is not possible because result.user returns type of User?
SharedPreferenceHelper().saveUserEmail(userDetails.email!);

Note: Follow the same steps for userDetails.uid,userDetails.photoUrl,userDetails.displayName