/**
* Builds a Form that mirrors the parent editForm, but with an extra field to collect the ChangeSet ID
*
* @param DataObject $object The object we're going to be adding to whichever ChangeSet is chosen
* @return Form
*/
public function Form($object)
{
$inChangeSets = array_unique(ChangeSetItem::get_for_object($object)->column('ChangeSetID'));
$changeSets = $this->getAvailableChangeSets()->map();
$campaignDropdown = DropdownField::create('Campaign', '', $changeSets);
$campaignDropdown->setEmptyString(_t('Campaigns.AddToCampaignFormFieldLabel', 'Select a Campaign'));
$campaignDropdown->addExtraClass('noborder');
$campaignDropdown->addExtraClass('no-chosen');
$campaignDropdown->setDisabledItems($inChangeSets);
$fields = new FieldList([$campaignDropdown, HiddenField::create('ID', null, $this->data['ID']), HiddenField::create('ClassName', null, $this->data['ClassName'])]);
$form = new Form($this->controller, $this->name, $fields, new FieldList($action = AddToCampaignHandler_FormAction::create()));
$action->addExtraClass('add-to-campaign__action');
$form->setHTMLID('Form_EditForm_AddToCampaign');
$form->loadDataFrom($this->data);
$form->getValidator()->addRequiredField('Campaign');
$form->addExtraClass('form--no-dividers add-to-campaign__form');
return $form;
}
