Validate username and email crashed and cannot insert to firebase database

Question

The apps cannot insert any data to the database while this line of code makes error to the apps.

ref.child(uid).orderByChild(\"username\").equalTo(validateName)         


        

Answer 1

As your error said, Firebase Database paths must not contain '.', '#', '$', '[', or ']'. This means that Firebase does not allow you use in the key symbols those symbols. Because of that, you need to econde the email address like this:

name@email.com -> name@email,com

To achieve this, i recomand you using the following methods:

static String encodeUserEmail(String userEmail) {
    return userEmail.replace(".", ",");
}

static String decodeUserEmail(String userEmail) {
    return userEmail.replace(",", ".");
}

Answer 2

Now currently my code will be like this so where to change that to exists?

ref.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {

                    for(DataSnapshot c : dataSnapshot.getChildren()){

                        String vun = c.child("username").getValue().toString();

                        if (vun.equalsIgnoreCase(usnm)){

                            Toast.makeText(Register.this, "Username Taken. Please try another one.", LENGTH_SHORT).show();
                            return;

                        }
                    }//end of for loop
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {


                }
            });// end of addvalue