Generate a dynamic username with the Gravity Forms User Registration add-on in a multisite

As mentioned in previous blog post, I use Gravity Forms quite often when creating forms. It also offers some great add-ons. One of this add-ons is the User Registation. With the help of this extension, you can create a WordPress user, after the form was submitted.

The “username” field

You basically set up a regular form. In this form you should ask for some manadtory fields you would need to create a user account. As a bare minimum, your should ask for an email address, so users can activate their account. Other fields might be first and last name. But what about a username? The add-on offers a special field for usernames. When you want to enable users to pick their own name, this is a perfect field to add.

Use the “email” field

As WordPress allows any user to login either with their username or with their email address, they might not even need to know their username. So when creating the “Feed” to create a user, you could just use the email field. Unless you are creating users for a multisite.

Create a dynamic username using other fields

In a multisite installation, a username can only contain lower case letters and numbers. This is because the username “can” be used for a subsite per user. But even if you don’t plan to have a site per user (which the add-on could also create for you), this constraint still applies. So how to deal with that without asking your users to pick their own username? Simply create a dynamic username using other fields.

Use the first and last name fields

On many platforms, your username will automatically be a combination of your first and last name. So we can use a filter to create such a username. But as this username may still contain some invalid characters, we have to “sanitize” it. Fortunately WordPress offers a function for that. And as two new users may have the same first and last name, we need to find a way to solve that as well. But let’s start with the callback function to the Gravity Forms hook first:

function gf_ms_get_unique_username( $username, $feed, $form, $entry ) {
        // Get first and last name from the form submission.
        $first_name = rgar( $entry, rgars( $feed, 'meta/first_name' ) );
        $last_name  = rgar( $entry, rgars( $feed, 'meta/last_name' ) );

        // Generate a new username making it compatible with multisite constraints.
        $new_username = gf_ms_uf_get_unique_username( sanitize_user( $first_name . $last_name ) );

        if ( ! empty ( $new_username ) ) {
                $username = $new_username;

        return $username;
add_filter( 'gform_username', 'gf_ms_uf_set_username', 10, 4 );

Here we use the hook gform_username which is used for the special username field. In the callback we get the values from the first and last name fields and pass them to our helper function to generate a unique username. If we get a new username, we return it.

Generating a unique username

Now how do we get this unique username? Well, we just need a method similar to the one that WordPress uses to get unique permalinks for posts/pages/terms with the same name. We use a “counter suffix” until the username is unique:

function gf_ms_get_unique_username( $username ) {
        $number            = 2;
        $original_username = $username;

        while ( username_exists( $username ) || gf_ms_signup_exists( $username ) ) {
                $username = $original_username . $number ++;

        return $username;

function gf_ms_signup_exists( $username ) {
        global $wpdb;

        return $wpdb->get_row(
                "SELECT * FROM $wpdb->signups WHERE user_login = %s",

In the while loop we check not only if the username already exists, but also if the username has been used by a previous user who already signed up, but hasn’t confirmed his account using the activation link received by mail. To check this, we use another helper function with code similar to the one in Core.


WordPress does offer a native way to sign up new users – to single sites or multisite. But if you want to ask the new users for additional information, an add-on like the one from Gravity Forms can really improve the sign-up process. Signing up users for a multisite can be tricky, but with some good helper functions, this can also be solved. As always, you can find the code from this blog post in a GIST where you can also download it as a ZIP and install it as a plugin.

Posted by

Bernhard is a full time web developer who likes to write WordPress plugins in his free time and is an active member of the WP Meetups in Berlin and Potsdam.

Leave a Reply

Your email address will not be published. Required fields are marked *