Registration of frontend plugins¶

When you want to use Extbase controllers in the frontend you need to define a so called frontend plugin. Extbase allows to define multiple frontend plugins for different use cases within one extension.

A frontend plugin can be defined as content element or as pure TypoScript frontend plugin.

Content element plugins can be added by editors to pages in the Page module while TypoScript frontend plugin can only be added via TypoScript or Fluid in a predefined position of the page. All content element plugins can also be used as TypoScript plugin.

Frontend plugin as content element¶

The plugins in the New Content Element wizard¶

Use the following steps to add the plugin as content element:

configurePlugin(): Make the plugin available in the frontend
EXT:blog_example/ext_localconf.php¶
```
<?php

declare(strict_types=1);

use FriendsOfTYPO3\BlogExample\Controller\CommentController;
use FriendsOfTYPO3\BlogExample\Controller\PostController;
use TYPO3\CMS\Extbase\Utility\ExtensionUtility;

defined('TYPO3') or die();

ExtensionUtility::configurePlugin(
    // extension name, matching the PHP namespaces (but without the vendor)
    'BlogExample',
    // arbitrary, but unique plugin name (not visible in the backend)
    'PostSingle',
    // all actions
    [PostController::class => 'show', CommentController::class => 'create'],
    // non-cacheable actions
    [CommentController::class => 'create']
);
```
Use the following parameters:
1. Extension key 'blog_example' or name BlogExample.
2. A unique identifier for your plugin in UpperCamelCase: 'PostSingle'
3. An array of allowed combinations of controllers and actions stored in an array
4. (Optional) an array of controller name and action names which should not be cached
TYPO3\CMS\Extbase\Utility\ExtensionUtility::configurePlugin() generates the necessary TypoScript to display the plugin in the frontend.

In the above example the actions show in the PostController and create in the CommentController are allowed. The later action should not be cached. This action can show different output depending on whether a comment was just added, there was an error in the input etc. Therefore the output of the action create of the CommentController should not be cached.

The action delete of the CommentController is not listed. This action is therefore not allowed in this plugin.

The TypoScript of the plugin will be available at tt_content.list.20.blogexample_postsingle. Additionally the lists of allowed and non-cacheable actions have been added to the according global variables.
registerPlugin(): Add to list_type tt_content.

Make the plugin available in the field Plugin > Selected Plugin, list_type of the table tt_content.

The new plugin in the content record at Plugin > Selected Plugin
EXT:blog_example/Configuration/TCA/Overrides/tt_content.php¶
```
<?php

defined('TYPO3') or die();

(static function (): void {
    \TYPO3\CMS\Extbase\Utility\ExtensionUtility::registerPlugin(
        // extension name, matching the PHP namespaces (but without the vendor)
        'BlogExample',
        // arbitrary, but unique plugin name (not visible in the backend)
        'PostSingle',
        // plugin title, as visible in the drop-down in the backend, use "LLL:" for localization
        'Single Post (BlogExample)'
    );
})();
```
Use the following parameters:
1. Extension key 'blog_example' or name BlogExample.
2. A unique identifier for your plugin in UpperCamelCase: 'PostSingle', must be the same as used in configurePlugin() or the plugin will not render.
3. Plugin title in the backend: Can be a string or a localized string starting with LLL:.
4. (Optional) the icon identifier or file path prepended with "EXT:"
(Optional) Add to the New Content Element wizard

Add the following page TSconfig to add the new plugin to the wizard:
EXT:blog_example/Configuration/page.tsconfig¶
```
mod.wizards.newContentElement.wizardItems {
  // add the content elementS to the tab "plugins"
  plugins {
    elements {
      // ...
      blogexample_postsingle {
        iconIdentifier = blog_example_icon
        title = PostSingle
        description = Display a single blog post
        tt_content_defValues {
          CType = list
          list_type = = blogexample_postsingle
        }
      }
    }

    show := addToList(blogexample_postlist,blogexample_postsingle,blogexample_blogadmin)
  }
}
```
- Line 6: The plugin signature: The extension name in lowercase without underscores, followed by one underscore, followed by the plugin identifier in lowercase without underscores.
- Line 7: Should be the same icon like used in registerPlugin() for consistency
- Line 8: Should be the same title like used in registerPlugin() for consistency
- Line 9: Additional description: Can be a string or a localized string starting with LLL:.
- Line 12: The plugin signature as list_type
- Line 16: Add the plugin signature as to the list of allowed content elements
In TYPO3 v11 you still need to include the page TSconfig file, in TYPO3 v12 it is automatically globally included.

See Setting the page TSconfig globally.

Frontend plugin as pure TypoScript¶

configurePlugin(): Make the plugin available in the frontend

Configure the plugin just like described in Frontend plugin as content element. This will create the basic TypoScript and the lists of allowed controller-action combinations.

In this example we define a plugin displaying a list of posts as RSS feed:
EXT:blog_example/ext_localconf.php¶
```
<?php

declare(strict_types=1);

use FriendsOfTYPO3\BlogExample\Controller\PostController;
use TYPO3\CMS\Extbase\Utility\ExtensionUtility;

defined('TYPO3') or die();

// RSS feed
ExtensionUtility::configurePlugin(
    'BlogExample',
    'PostListRss',
    [PostController::class => 'displayRssList']
);
```

Display the plugin via TypoScript

The TypoScript USER object saved at tt_content.list.20.blogexample_postlistrss can now be used to display the frontend plugin. In this example we create a special page type for the RSS feed and display the plugin via TypoScript there:

EXT:blog_example/Configuration/TypoScript/RssFeed/setup.typoscript¶

# RSS rendering
tx_blogexample_rss = PAGE
tx_blogexample_rss {
  typeNum = {$plugin.tx_blogexample.settings.rssPageType}
  10 < tt_content.list.20.blogexample_postlistrss

  config {
    disableAllHeaderCode = 1
    xhtml_cleaning = none
    admPanel = 0
    debug = 0
    disablePrefixComment = 1
    metaCharset = utf-8
    additionalHeaders.10.header = Content-Type:application/rss+xml;charset=utf-8
    linkVars >
  }
}