Plugin Registration

#Introduction

Plugins are the foundation for adding new features or extending the base functionality of Winter CMS. The plugin registration process allows plugins to declare their features such as components, navigation items and Backend pages. Some examples of what a plugin can do:

• Define components.
• Define user permissions.
• Add settings pages, menu items, lists and forms.
• Create database table structures and seed data.
• Alter functionality of the core or other plugins.
• Provide classes, backend controllers, views, assets, and other files.

#Directory structure

Plugins reside in the plugins directory of your Winter CMS installation. The most simple plugin only requires two files, but they can accomodate all the way up to entire application structures as required by your plugin complexity.

#Simple plugin structure

The simplest plugins only require a Plugin.php file and an updates/version.yaml described below.

plugins/
`-- myauthor/                 # Author name
    `-- myplugin/             # Plugin name
        |-- updates/          # Updates and migrations folder
        |   `-- version.yaml  # Change log, required
        `-- Plugin.php        # Plugin registration file, required

#Typical plugin structure

The following is an example of what most plugins would end up looking like when interacting with the most commonly used Winter CMS functionality.

plugins/
`-- myauthor/                  # Author name
    `-- myplugin/              # Plugin name
        |-- assets/            # CSS, JavaScript and image assets for pages and components
        |-- components/        # Frontend components
        |-- controllers/       # Backend controllers and views
        |-- lang/              # Localization files
        |   `-- en/            # Specific locale folder
        |       `-- lang.php   # Translations
        |-- models/            # Database models
        |-- updates/           # Updates and migrations folder
        |   `-- version.yaml   # Change log
        |-- views/             # Custom view files
        |   `-- mail/          # Custom mail templates
        |-- Plugin.php         # Plugin registration file
        `-- README.md          # Documentation describing the plugin, its requirements and its purpose

#Comprehensive plugin structure

The following is an example of what a comprehensive plugin that uses or provides a signficant number of features in Winter CMS could look like.

plugins/
`-- myauthor/                           # Author name
    `-- myplugin/                       # Plugin name
        |-- assets/                     # CSS, JavaScript and image assets for pages and components
        |   |-- css/
        |   |-- favicons/
        |   |-- images/
        |   |-- js/
        |   |-- less/
        |   `-- scss/
        |-- behaviors/                  # Custom behaviors provided by the plugin
        |-- classes/                    # Custom classes and functionality that are outside the structure of Winter CMS
        |-- components/                 # Frontend components
        |   |-- record/
        |   |   `-- default.htm         # A default partial to be used for the component in the Twig content
        |   `-- Record.php              # The component definition class
        |-- config/                     # Plugin-provided configuration
        |   `-- config.php
        |-- controllers/                # Backend controllers and views
        |   |-- records/                # A folder for a controller's assets, configuration, views and partials
        |   |   |-- _list_toolbar.php   # A partial template that can be used in the controller views
        |   |   |-- config_filter.yaml  # The filter widget configuration
        |   |   |-- config_form.yaml    # The form controller configuration
        |   |   |-- config_list.yaml    # The list controller configuration
        |   |   |-- create.php          # The "create" view for the form controller
        |   |   |-- index.php           # The "index" view for the list controller
        |   |   |-- preview.php         # The "preview" view for the form controller
        |   |   `-- update.php          # The "update" view for the form controller
        |   `-- Records.php             # The controller class
        |-- docs/                       # Plugin documentation
        |-- formwidgets/                # Custom form widgets
        |-- lang/                       # Localization files
        |   `-- en/                     # Specific locale folder
        |       `-- lang.php            # Translations
        |-- layouts/                    # Custom backend layouts
        |-- models/                     # Database models
        |   |-- record/                 # A folder for a model's configuration and partials
        |   |   |-- columns.yaml        # The column configuration for the model for lists
        |   |   `-- fields.yaml         # The form configuration for the model for forms
        |   `-- Record.php              # The model class
        |-- partials/                   # Custom partials used within the plugin
        |-- reportwidgets/              # Custom report widgets
        |-- tests/                      # Unit tests
        |-- traits/                     # Custom traits
        |-- updates/                    # Updates and migrations folder
        |   |-- create_tables.php       # A migration to be run during a version update
        |   `-- version.yaml            # Change log
        |-- views/                      # Custom view files
        |   `-- mail/                   # Custom mail templates
        |-- composer.json               # Composer file to identify the plugin and define dependencies
        |-- helpers.php                 # Custom helper methods provided by the plugin.
        |-- LICENSE                     # License file
        |-- phpunit.xml                 # Unit testing configuration
        |-- Plugin.php                  # Plugin registration file, required
        |-- README.md                   # Documentation describing the plugin, its requirements and its purpose
        `-- routes.php                  # Custom routing

#Plugin namespaces

Plugin namespaces are very important, especially if you are going to publish your plugins on the Winter Marketplace. By using a unique plugin namespace, you remove the chance that your plugin conflicts with another author.

When you register as an author on the Marketplace, you will be asked for the author code which should be used as a root namespace for all your plugins. You can specify the author code only once, when you register.

The default author code offered by the Marketplace consists of the author first and last name: JohnSmith. The code cannot be changed after you register. All your plugin namespaces should be defined under the root namespace, for example \JohnSmith\Blog.

#Registration file

The Plugin.php file, called the Plugin registration file, is an initialization script that declares a plugin's core functions and information. This file is read in the boot process of Winter CMS when determining available plugins. Registration files can provide the following:

1. Information about the plugin, its name, and author.
2. Registration methods for extending the CMS and stating the intentions of the plugin.

Registration scripts should use the plugin namespace. The registration script should define a class with the name Plugin that extends the \System\Classes\PluginBase class. The only required method of the plugin registration class is the pluginDetails method. An example Plugin registration file:

<?php

namespace Acme\Blog;

class Plugin extends \System\Classes\PluginBase
{
    public function pluginDetails()
    {
        return [
            'name' => 'Blog Plugin',
            'description' => 'Provides some really cool blog features.',
            'author' => 'ACME Corporation',
            'icon' => 'icon-snowflake-o'
        ];
    }

    public function registerComponents()
    {
        return [
            'Acme\Blog\Components\Post' => 'blogPost'
        ];
    }
}

#Supported methods

The following methods are supported in the plugin registration class:

#Basic plugin information

The pluginDetails is a required method of the plugin registration class. It should return an array containing the following keys:

#Routing and initialization

Plugin registration files can contain two methods: boot and register. These methods are run at separate points in the Winter CMS boot process.

The register method is called immediately when the plugin is found and the Plugin registration file is read. It can be used to register or provide global services, define functionality within the underlying framework or initialize functionality for the plugin.

public function register()
{
    App::register(MyProviderClass::class, function ($app) {
        return new MyProviderClass();
    });
}

NOTE: The register method is run very early on in the Winter CMS boot process, and some functions within Winter CMS or Laravel may not be available at that stage, especially in respect to third-party plugins or services. You should use the boot method for any functionality that is dependent on third-party plugins or services.

The boot method is called after all services are loaded and all plugins are registered. This method should be used to define functionality that is to be run on each page load, such as extending plugins or attaching to events.

public function boot()
{
    User::extend(function($model) {
        $model->hasOne['author'] = ['Acme\Blog\Models\Author'];
    });
}

The boot and register methods are not called during the update process, or within some critical Backend sections and command-line tools, to protect the system from critical errors. To overcome this limitation, use elevated permissions.

Plugins can also supply a file named routes.php that may contain custom routing logic, as defined in the router service. For example:

Route::group(['prefix' => 'api_acme_blog'], function() {
    Route::get('cleanup_posts', function(){ return Posts::cleanUp(); });
});

Finally, plugins can also supply a file named init.php. This file acts similar to the boot method in that it can be used to define functionality run on each page load, but in a more global context.

#Dependency definitions

A plugin can depend upon other plugins by defining a $require property in the Plugin registration file. The property should contain an array of plugin names that are considered requirements for this plugin to function. A plugin that depends on the Acme.User plugin can declare this requirement in the following way:

namespace Acme\Blog;

class Plugin extends \System\Classes\PluginBase
{
    /**
     * @var array Plugin dependencies
     */
    public $require = ['Acme.User'];

    // [...]
}

Dependency definitions will affect how the plugin operates and how the update process orders and applies updates. The installation process will attempt to install any dependencies automatically, however if a plugin is detected in the system without any of its dependencies, it will be automatically disabled to prevent system errors.

Care should be taken to ensure that circular dependency references are not made - for example, if the Acme.Demo plugin depends on the Acme.Blog plugin, the Acme.Blog plugins should not also depend on the Acme.Demo plugin.

#Extending Twig

Custom Twig filters and functions can be registered in the CMS with the registerMarkupTags method of the plugin registration class.

Twig options are also able to be passed to change the behavior of the registered filters & functions by providing an array with an 'options' element containing the options to be passed at time of registration where the callable value would be provided normally. If options are provided, then the callable handler for the filter / function being registered must either be present in a 'callable' element or as the first element of the array.

IMPORTANT: All custom Twig filters & functions registered via the MarkupManager (i.e. registerMarkupTags() will have the is_safe option set to ['html'] by default, which means that Twig's automatic escaping is disabled by default (effectively it's as if the | raw filter was always located after your filter or function's output) unless you provide the is_safe option during registration ('options' => ['is_safe' => []]).

The next example registers three Twig filters and three functions.

public function registerMarkupTags()
{
    return [
        'filters' => [
            // A global function, i.e str_plural()
            'plural' => 'str_plural',

            // A local method, i.e $this->makeTextAllCaps()
            'uppercase' => [$this, 'makeTextAllCaps'],

            // Any callable with custom options defined - first element method
            'userInputToEmojis' => ['input_to_emojis', 'options' => ['is_safe' => []]],
        ],
        'functions' => [
            // A static method call, i.e Form::open()
            'form_open' => ['Winter\Storm\Html\Form', 'open'],

            // Using an inline closure
            'helloWorld' => function() { return 'Hello World!'; },

            // Any callable with custom options defined - named 'callable' method
            'goodbyeWorld' => [
                'callable' => ['Acme\Plugin\Nuke', 'boom'],
                'options'  => ['needs_environment' => true],
            ],
        ],
    ];
}

public function makeTextAllCaps($text)
{
    return strtoupper($text);
}

The following Twig custom options are available:

#Navigation menus

Plugins can extend the backend navigation menus by overriding the registerNavigation method of the Plugin registration class. This section shows you how to add menu items to the backend navigation area. An example of registering a top-level navigation menu item with two sub-menu items:

public function registerNavigation()
{
    return [
        'blog' => [
            'label'       => 'Blog',
            'url'         => Backend::url('acme/blog/posts'),
            'icon'        => 'icon-pencil',
            'permissions' => ['acme.blog.*'],
            'order'       => 500,
            // Set counter to false to prevent the default behaviour of the main menu counter being a sum of
            // its side menu counters
            'counter'     => ['\Author\Plugin\Classes\MyMenuCounterService', 'getBlogMenuCount'],
            'counterLabel'=> 'Label describing a dynamic menu counter',
            // Optionally you can set a badge value instead of a counter to display a string instead of a numerical counter
            'badge'       => 'New',

            'sideMenu' => [
                'posts' => [
                    'label'       => 'Posts',
                    'icon'        => 'icon-copy',
                    'url'         => Backend::url('acme/blog/posts'),
                    'permissions' => ['acme.blog.access_posts'],
                    'counter'     => 2,
                    'counterLabel'=> 'Label describing a static menu counter',
                ],
                'categories' => [
                    'label'       => 'Categories',
                    'icon'        => 'icon-copy',
                    'url'         => Backend::url('acme/blog/categories'),
                    // If the value is a callable and it returns `0`, then it will be treated as if it returns `null`, displaying nothing.
                    // If the value is an explicit value, then `0` will be displayed if provided.
                    'counter'     => 0,
                    'permissions' => ['acme.blog.access_categories'],
                ]
            ]
        ]
    ];
}

When you register the backend navigation you can use localization strings for the label values. Backend navigation can also be controlled by the permissions values and correspond to defined backend user permissions. The order in which the backend navigation appears on the overall navigation menu items, is controlled by the order value. Higher numbers mean that the item will appear later on in the order of menu items while lower numbers mean that it will appear earlier on.

To make the sub-menu items visible, you may set the navigation context in the backend controller using the BackendMenu::setContext method. This will make the parent menu item active and display the children in the side menu.

#Registering middleware

To register a custom middleware, you can apply it directly to a backend controller in your plugin by using Controller middleware, or you can extend a Controller class by using the following method.

public function boot()
{
    \Cms\Classes\CmsController::extend(function($controller) {
        $controller->middleware('Path\To\Custom\Middleware');
    });
}

Alternatively, you can push it directly into the Kernel via the following.

public function boot()
{
    // Add a new middleware to beginning of the stack.
    $this->app['Illuminate\Contracts\Http\Kernel']
        ->prependMiddleware('Path\To\Custom\Middleware');

    // Add a new middleware to end of the stack.
    $this->app['Illuminate\Contracts\Http\Kernel']
        ->pushMiddleware('Path\To\Custom\Middleware');
}

#Elevated permissions

By default plugins are restricted from running when operating in certain areas of the system. This is to prevent critical errors that may lock an administrator out from the backend. When these areas are accessed, the boot and register initialization methods will not fire for plugins that are not elevated.

When running any commands from the CLI while your application has a database connection configured but the migrations table is not yet present on it, the application will also be considered in a protected state.

Define the $elevated property to grant elevated permissions for your plugin.

/**
 * @var bool Plugin requires elevated permissions.
 */
public $elevated = true;