级联更新

<class id="Ticket" _delta="must_exist">
  <fields>
    <field id="workorders_list">
      <with_php_computation _delta="force">true</with_php_computation>
    </field>
  </fields>
</class>

protected function ComputeTimeSpent(?Combodo\iTop\Service\Events\EventData $oEventData)
{
   $iSum = 0;
   $oWorkOrderSet = $this->Get('workorders_list');
   while($oWorkOrder = $oWorkOrderSet->Fetch()) {
        $iSum += $oWorkOrder->Get('time_spent');
   }
   $this->Set('time_spent', $iSum);
}
public function BeforeWrite(Combodo\iTop\Service\Events\EventData $oEventData)
{
  $aChanges = $this->ListChanges();
  if (array_key_exists('workorders_list', $aChanges)) {
      $this->ComputeTimeSpent(null);
  }
}
public function HideTimeSpent(Combodo\iTop\Service\Events\EventData $oEventData)
{   
    $this->ForceInitialAttributeFlags('time_spent', OPT_ATT_HIDDEN ); 
}
public function MakeTimeSpentReadOnly(Combodo\iTop\Service\Events\EventData $oEventData)
{   
    $this->ForceAttributeFlags('time_spent', OPT_ATT_READONLY); 
}