validation - In CakePHP3 how do I create a custom model rule which validates that a time is after another time in the same table? -

columns (both datatype time):

start end 

end cannot before start.

    $validator     ->requirepresence('end', 'create')         ->notempty('end')         ->add('end', [                     'time' => [                             'rule'      => 'time',                             'message'   => 'end can accept times.'                             ],                     'dependency' => [                             'rule'  => [$this, 'endbeforestart'],                             'message'   => 'end can not before start.'                         ],                 ]); 

if put request contains end, model need query existing record compare against start. if put contains both need validate against intended new parameter.

how cakephp3 this?

private function endbeforestart($fieldvaluetobevalidated, $datarelatedtothevalidationprocess) { //what goes here? } 

i can't seem find examples of doing online.

i'm not quite sure , haven't tested it, maybe gives hints:

$validator ->add('end', [   'endbeforestart' => [     'rule' => function ($value, $context) {       // if it's post (new entry):       if ( $context['newrecord'] == '1' ) {         // comparison here         // input values e.g. in $context['data']['starttime']         // if end before start:         return false;       }       // if it's put (update):       else {         // if starttime not in $context['data']['starttime']         // check old value in $getoldentry         $getoldentry = $this->getoldentry( $context['data']['id'] );         // , comparison here...         // if end before start:         return false;       }       return true;     },     'message' => 'end can not before start.' ],   ])  public function getoldentry($id = null) {   return $this->get($id); } 

i'm not sure if last function has private or public...