Silverstripe - Generic search form doesn't work on Security/Login page

I have defined a searchform in the Page.php file

function AdvancedSearchForm() { $searchText = isset($this->Query) ? $this->Query : 'Search'; $searchText2 = isset($this->Subquery) ? $this->Subquery : '0'; $searchText3 = isset($this->documentType) ? $this->documentType : 'All';

$searchSections = DataObject::get('SearchSection');
$ss = array();
foreach ($searchSections as $section) {
    $ss[$section->ID] = $section->Name;
}

$fileTypes = DataObject::get('FileType');
$ft = array();
foreach ($fileTypes as $type) {
    $ft[$type->ID] = $type->Name;
}
$ft[0] = 'All';
ksort($ft);

$fields = new FieldSet(
    new TextField('Query','Keywords', $searchText),
    new DropdownField('Subquery', '', $ss, $searchText2),
    new DropdownField('documentType', '', $ft, $searchText3)
);
$actions = new FieldSet(
    new FormAction('AdvancedSearchResults', 'Search')
);
$form = new Form($this->owner, 'AdvancedSearchForm', $fields, $actions);
$form->setFormMethod('GET');
$form->setTemplate('Includes/SearchForm');
$form->disableSecurityToken();

return $form;

}

and all my pages are extended from Page and search form is in the header so appears on all pages. But when user is on Security/Login page and tries to search for something, he gets the following error message

The action 'AdvancedSearchForm' does not exist in class Security

I assume the reason for this is Securit开发者_如何学Pythony page is not extended from Page. How can I set the search from so that it will work on any page including system pages such as Security login page?

---

You are getting an error because the form is not being passed to the controller you want (~Page_Controller).

When you define the Form object, you should test $this->owner and see if it's a descendant of Page_Controller. If not, you could use something like this and use $controller as the first variable in your Form object creation.

$sitetree_object = SiteTree::get_by_link('some-page-url');
$controller = ModelAsController::controller_for($sitetree_object);