The user model can validate usernames

application/models/Users_model.php

@@ -417,4 +417,22 @@ class Users_model extends EA_Model {
     {
         // Users do not currently have any related resources. 
     }
+
+    /**
+     * Validate the username.
+     *
+     * @param string $username Username.
+     * @param int|null $user_id Exclude user ID.
+     *
+     * @return bool Returns the validation result.
+     */
+    public function validate_username(string $username, int $user_id = NULL): bool
+    {
+        if ( ! empty($user_id))
+        {
+            $this->db->where('id_users !=', $user_id);
+        }
+
+        return $this->db->get_where('user_settings', ['username' => $username])->num_rows() === 0;
+    }
 }