Easy Digital Downloads - Add twitter field to EDD Register form and save it to usermeta

gistfile1.php

/**
 * Add new twitter field to EDD register form
 */
function sumobi_edd_add_registration_field() {
	?>

	<p>
		<label for="edd-user-twitter-username"><?php _e( 'Twitter Username', 'edd' ); ?></label>
		<input id="edd-user-twitter-username" class="edd-input" type="text" name="edd_user_twitter_username" />
	</p>

	<?php
}
add_action( 'edd_register_form_fields_before_submit', 'sumobi_edd_add_registration_field' );


/**
 * Insert twitter username into usermeta
 * Will store into a metakey called twitter_username
 */
function sumobi_edd_insert_user_data( $user_id, $user_data ) {
	
	$twitter_username = isset( $_POST['edd_user_twitter_username'] ) ? sanitize_text_field( $_POST['edd_user_twitter_username'] ) : '';

	if ( $twitter_username ) {
		update_user_meta( $user_id, 'twitter_username', $twitter_username );
	}
	
}
add_action( 'edd_insert_user', 'sumobi_edd_insert_user_data', 10, 2 );