Method addUserToGroup

/**
 * Method to add a user to a group.
 *
 * @param   integer  $userId   The id of the user.
 * @param   integer  $groupId  The id of the group.
 *
 * @return  boolean  True on success
 *
 * @since   1.7.0
 * @throws  \RuntimeException
 */
public static function addUserToGroup($userId, $groupId)
{
    // Cast as integer until method is typehinted.
    $userId = (int) $userId;
    $groupId = (int) $groupId;
    // Get the user object.
    $user = new User($userId);
    // Add the user to the group if necessary.
    if (!\in_array($groupId, $user->groups)) {
        // Check whether the group exists.
        $db = Factory::getDbo();
        $query = $db->getQuery(true)->select($db->quoteName('id'))->from($db->quoteName('#__usergroups'))->where($db->quoteName('id') . ' = :groupId')->bind(':groupId', $groupId, ParameterType::INTEGER);
        $db->setQuery($query);
        // If the group does not exist, return an exception.
        if ($db->loadResult() === null) {
            throw new \RuntimeException('Access Usergroup Invalid');
        }
        // Add the group data to the user object.
        $user->groups[$groupId] = $groupId;
        // Reindex the array for prepared statements binding
        $user->groups = array_values($user->groups);
        // Store the user object.
        $user->save();
    }
    // Set the group data for any preloaded user objects.
    $temp = User::getInstance($userId);
    $temp->groups = $user->groups;
    if (Factory::getSession()->getId()) {
        // Set the group data for the user object in the session.
        $temp = Factory::getUser();
        if ($temp->id == $userId) {
            $temp->groups = $user->groups;
        }
    }
    return true;
}