/**
* Determine if the given member belongs to the given relation.
*
* @param Member $member
* @param DataList $relation
*
* @return bool
*/
protected function isMemberOf($member, $relation)
{
if (!$member || !$member->exists()) {
return false;
}
if ($relation instanceof UnsavedRelationList) {
return in_array($member->ID, $relation->getIDList());
}
return $relation->byID($member->ID) !== null;
}