/**
* Add a group_id to the list of _groups to which this User belongs, checking that the Group exists and the User isn't already a member.
*
* This method does NOT modify the database. Call `store` to persist to database.
* @param int $group_id The id of the group to add the user to.
* @throws Exception The specified group does not exist.
* @return User this User object.
*/
public function addGroup($group_id)
{
$this->getGroupIds();
// Return if user already in group
if (in_array($group_id, $this->_groups)) {
return $this;
}
// Next, check that the requested group actually exists
if (!Group::find($group_id)) {
throw new \Exception("The specified group_id ({$group_id}) does not exist.");
}
// Ok, add to the list of groups
$this->_groups[] = $group_id;
return $this;
}
