src/extensions/ControllerExtension.php
public function SearchForm()
    {
        // If we have setup objects to search
        if (count(Searchable::config()->objects)) {
            $searchText =  "";

            if ($this->owner->request && $this->owner->request->getVar('Search')) {
                $searchText = $this->owner->request->getVar('Search');
            }

            $fields = FieldList::create(
                TextField::create('Search', false, $searchText)
                    ->setAttribute("placeholder", _t('Searchable.Search', 'Search'))
            );

            $actions = FieldList::create(
                FormAction::create('results', _t('Searchable.Go', 'Go'))
            );

            $template_class = Searchable::config()->template_class;
            $results_page = Injector::inst()->create($template_class);

            $form = Form::create(
                $this->owner,
                'SearchForm',
                $fields,
                $actions
            )->setFormMethod('get')
            ->setFormAction($results_page->Link())
            ->setTemplate('ilateral\SilverStripe\Searchable\Includes\SearchForm')
            ->disableSecurityToken();

            $this->owner->extend("updateSearchForm", $form);

            return $form;
        }
    }
public function SearchForm()
    {
        // If we have setup objects to search
        if (count(Searchable::config()->objects)) {
            $searchText =  "";

            if ($this->owner->request && $this->owner->request->getVar('Search')) {
                $searchText = $this->owner->request->getVar('Search');
            }

            $fields = FieldList::create(
                TextField::create('Search', false, $searchText)
                    ->setAttribute("placeholder", _t('Searchable.Search', 'Search'))
            );

            $actions = FieldList::create(
                FormAction::create('results', _t('Searchable.Go', 'Go'))
            );

            $template_class = Searchable::config()->template_class;
            $results_page = Injector::inst()->create($template_class);

            $form = Form::create(
                $this->owner,
                'SearchForm',
                $fields,
                $actions
            )->setFormMethod('get')
            ->setFormAction($results_page->Link())
            ->setTemplate('ilateral\SilverStripe\Searchable\Includes\SearchForm')
            ->disableSecurityToken();

            $this->owner->extend("updateSearchForm", $form);

            return $form;
        }
    }
Add a site search form to all controllers that links to the
results controller.

@return Form