Check if given email exists

Question

Is there a way to know if the email entered by user is real in Firebase? Does the built-in sign up with email&password method have this feature?

EDIT: sorry for the misunderstanding . I don't care if the email has been used before , what I need to know is: if the entered email is 'made-up' or 'real , exists'

You're probably looking for this: http://stackoverflow.com/questions/40090406/ambiguous-use-of-subscript-swift-3/40092330#40092330 — Frank van Puffelen, Oct 17 '16 at 21:01
If you want to know whether the email address is actually owned by the user, your app can call user.sendEmailVerification(): https://firebase.google.com/docs/auth/android/manage-users#send_a_user_a_verification_email — Jin Liu, Oct 18 '16 at 21:15

J.Dragon · Answer 1 · 2020-10-23T11:51:22.443

40

This is another solution without any create user or sign in processes.

//check email already exist or not.
    firebaseAuth.fetchSignInMethodsForEmail(email)
            .addOnCompleteListener(new OnCompleteListener<SignInMethodQueryResult>() {
                @Override
                public void onComplete(@NonNull Task<SignInMethodQueryResult> task) {

                    boolean isNewUser = task.getResult().getSignInMethods().isEmpty();

                    if (isNewUser) {
                        Log.e("TAG", "Is New User!");
                    } else {
                        Log.e("TAG", "Is Old User!");
                    }

                }
            });

edited Oct 23 '20 at 11:51

answered Jul 09 '19 at 09:54

J.Dragon

699
8
16

If user exists with the email , then how to get UID of that user using this method ? – xaif May 28 '20 at 03:44
1

I think this solution is much better than all above mentioned solutions. – Waheed Nazir Aug 04 '20 at 15:55
This should be on the top!! – Anshul1507 Apr 13 '21 at 20:23

amrro · Answer 2 · 2016-10-17T21:04:29.133

Yes, you can do that either you create new account or signing in:

For creating, read createUserWithEmailAndPassword's Docs

createUserWithEmailAndPassword throws 3 exceptions:

FirebaseAuthWeakPasswordException: if the password is not strong enough
FirebaseAuthInvalidCredentialsException: if the email address is malformed
FirebaseAuthUserCollisionException: if there already exists an account with the given email address.

You can handle that in onCompleteListener or onFailureListener

Here an example where mAuth is FirebaseAuth instance:

mAuth.createUserWithEmailAndPassword(email, password)
            .addOnCompleteListener(
                    new OnCompleteListener<AuthResult>()
                    {
                        @Override
                        public void onComplete(@NonNull Task<AuthResult> task)
                        {
                            if (!task.isSuccessful())
                            {
                                try
                                {
                                    throw task.getException();
                                }
                                // if user enters wrong email.
                                catch (FirebaseAuthWeakPasswordException weakPassword)
                                {
                                    Log.d(TAG, "onComplete: weak_password");

                                    // TODO: take your actions!
                                }
                                // if user enters wrong password.
                                catch (FirebaseAuthInvalidCredentialsException malformedEmail)
                                {
                                    Log.d(TAG, "onComplete: malformed_email");

                                    // TODO: Take your action
                                }
                                catch (FirebaseAuthUserCollisionException existEmail)
                                {
                                    Log.d(TAG, "onComplete: exist_email");

                                    // TODO: Take your action
                                }
                                catch (Exception e)
                                {
                                    Log.d(TAG, "onComplete: " + e.getMessage());
                                }
                            }
                        }
                    }
            );

For signing in, read signInWithEmailAndPassword's Docs first.

signInWithEmailAndPassword throws two exceptions:

FirebaseAuthInvalidUserException: if email doesn't exist or disabled.
FirebaseAuthInvalidCredentialsException: if password is wrong

Here is an example:

mAuth.signInWithEmailAndPassword(email, password)
            .addOnCompleteListener(
                    new OnCompleteListener<AuthResult>()
                    {
                        @Override
                        public void onComplete(@NonNull Task<AuthResult> task)
                        {
                            if (!task.isSuccessful())
                            {
                                try
                                {
                                    throw task.getException();
                                }
                                // if user enters wrong email.
                                catch (FirebaseAuthInvalidUserException invalidEmail)
                                {
                                    Log.d(TAG, "onComplete: invalid_email");

                                    // TODO: take your actions!
                                }
                                // if user enters wrong password.
                                catch (FirebaseAuthInvalidCredentialsException wrongPassword)
                                {
                                    Log.d(TAG, "onComplete: wrong_password");

                                    // TODO: Take your action
                                }
                                catch (Exception e)
                                {
                                    Log.d(TAG, "onComplete: " + e.getMessage());
                                }
                            }
                        }
                    }
            );

if you enter an email does not exist with your code the result is always wrong password... — DragonFire, Feb 02 '19 at 02:47

sh_ark · Answer 3 · 2022-06-09T07:09:55.903

EDIT: To check if user is 'made-up' or 'real', just send an email verification by calling FirebaseAuth.instance.currentUser.sendEmailVerification() and ask user to click the link sent in their email, if user is able to perform this action then email exists otherwise it's 'made-up'. Later you can check if email is verified or not by using this boolean FirebaseAuth.instance.currentUser.emailVerified. Hope this answers your question.

OLD ANSWER: In case someone is looking for a flutter answer, then a rather easiest way would be to just check if List<String> returned by fetchSignInMethodsForEmail contains 'password' string or not.

Here is sample code:

var methods = await FirebaseAuth.instance.fetchSignInMethodsForEmail(email);
if (methods.contains('password')) {
  ///  Email exists
}
else {
  ///  Email does not exist
}

Original source (google codelabs): https://github.com/flutter/codelabs/blob/4397b60355daab38e98ca967c47af9b7671e0fd9/firebase-get-to-know-flutter/step_05/lib/main.dart#L122

You can also use `EmailAuthProvider.PROVIDER_ID` , `GoogleAuthProvider.PROVIDER_ID`, `FacebookAuthProvider.PROVIDER_ID` for checking which is much safer and cleaner — Bitwise DEVS, Sep 05 '22 at 00:10

score 1 · Answer 4 · answered Mar 01 '17 at 05:02

This maybe late answer but just for someone passing by could get benefit from the answer. I think the best way to check if the email is exist or not is to send the verification email to the inputing email.

Try checking out this link

https://firebase.googleblog.com/2017/02/email-verification-in-firebase-auth.html

Firebase has provided really easy way to verify user email.

score 0 · Answer 5 · answered Apr 09 '21 at 06:29

0

Use this: task.getException().getMessage() to get the exception

answered Apr 09 '21 at 06:29

Junaid Nawab

1

score -3 · Answer 6 · answered Mar 28 '18 at 04:30

It would be almost impossible to check if the email entered exists, you can however check if the email string entered conforms to the valid email structure:

if(!isValidEmail(etEmail.getText().toString())) {
         Toast.makeText(getActivity(), "Invalid input for email", Toast.LENGTH_LONG).show();

Then like Jin Liu suggests, use the sendEmailVerification(), like:

 mFirebaseUser.sendEmailVerification().addOnCompleteListener(new OnCompleteListener<Void>() {
            @Override
            public void onComplete(@NonNull Task<Void> task) {
                if(task.isSuccessful())
                Toast.makeText(getContext(), "Email Verfication Sent", Toast.LENGTH_LONG).show();
                else {
                    try{
                        throw task.getException();
                    }catch (Exception e) {

                        Toast.makeText(getContext(), e.getMessage(), Toast.LENGTH_LONG).show();
                    }

                }
            }
        });

Check if given email exists

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