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DrupalTutorial/themes/bootstrap/docs/plugins/Prerender.md
2024-07-15 12:33:27 +02:00

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<!-- @file Documentation for the @BootstrapPrerender annotated plugin. -->
<!-- @defgroup -->
<!-- @ingroup -->
# @BootstrapPrerender
- [Create a plugin](#create)
- [Rebuild the cache](#rebuild)
---
## Create a plugin {#create}
We'll use `Link` implemented by this base theme as an example of how to add
custom classes and an icon to make the link look like a Bootstrap button. This
example will only work if the link is passed some sort of `#context` when the
render array is built, like the following:
```php
<?php
$build['my_button'] = [
'#type' => 'link',
'#title' => t('Download'),
'#url' => Url::fromUserInput('/download', [
'query' => ['item' => '1234'],
]),
'#context' => [
'downloadButton' => TRUE,
],
];
?>
```
Replace all following instances of `THEMENAME` with the actual machine name of
your sub-theme.
Create a file at `./themes/THEMENAME/src/Plugin/Prerender/Link.php` with the
following contents:
```php
<?php
namespace Drupal\THEMENAME\Plugin\Prerender;
use Drupal\bootstrap\Plugin\Prerender\Link as BootstrapLink;
use Drupal\bootstrap\Bootstrap;
use Drupal\bootstrap\Utility\Element;
/**
* Pre-render callback for the "link" element type.
*
* @ingroup plugins_prerender
*
* @BootstrapPrerender("link",
* action = @BootstrapConstant(
* "\Drupal\bootstrap\Bootstrap::CALLBACK_PREPEND"
* )
* )
*
* @see \Drupal\Core\Render\Element\Link::preRenderLink()
*/
class Link extends BootstrapLink {
/*
* It should be noted that you do not need both methods here.
* This is to just show you the different examples of how this plugin
* works and how it can be tailored to your needs.
*/
/**
* {@inheritdoc}
*/
public static function preRender(array $element) {
$context = isset($element['#context']) ? $element['#context'] : [];
// Make downloadButton links into buttons.
if (!empty($context['downloadButton'])) {
$element['#icon'] = Bootstrap::glyphicon('download-alt');
$element['#attributes']['class'][] = 'btn';
$element['#attributes']['class'][] = 'btn-primary';
$element['#attributes']['class'][] = 'btn-lg';
}
// You must always return the element in this method, as well as call the
// parent method when sub-classing this method as it is used to invoke
// static::preRenderElement().
return parent::preRender($element);
}
/**
* {@inheritdoc}
*/
public static function preRenderElement(Element $element) {
// Make downloadButton links into buttons.
// Same as above, just a little cleaner with the Element utility class.
if ($element->getContext('downloadButton')) {
$element->addClass(['btn', 'btn-primary', 'btn-lg'])->setIcon(Bootstrap::glyphicon('download-alt'));
}
// You don't always have to call the parent method when sub-classing, but
// it is generally recommended that you do (otherwise the icon that was
// just added wouldn't work).
parent::preRenderElement($element);
}
}
?>
```
## Rebuild the cache {#rebuild}
Once you have saved, you must rebuild your cache for this new plugin to be
discovered. This must happen anytime you make a change to the actual file name
or the information inside the `@BootstrapPrerender` annotation.
To rebuild your cache, navigate to `admin/config/development/performance` and
click the `Clear all caches` button. Or if you prefer, run `drush cr` from the
command line.
Voilà! After this, you should have a fully functional `@BootstrapPrerender`
plugin!