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Alright on the last article we promised that we were going to talk more about services, so this is what we are going to do here. Let’s delve right to it, another property of services is the configurator property, which is used to configure a service after it has been installed, where there is a service, which requires a complex setup. The configuration of the configurator property would usually come from a different source or service.
Another property of the service file is the factory property, which is where the service class is instantiated through a class. The file property is a file included just before the service, and the tags property is used to identify groups of services. There are other properties defined at drupal.org, I don’t want to focus too much on the property although they are very important.
Let’s continue to talk about the structure of the service files and directory. Now that we are aware of the different properties found in the service .yml file, let’s look at the other components needed to use a service. There is one more property, which is important to note, is known as the class property, which is used to point to any .php file found in the src/Services directory. The .php file will allow you to call your dependencies and use them however you need.
<?php
Class WatchCartoons {
…………
Public function __construct(ConfigFactory $cofig_factory) {
$this->config_factory = $config_factory
}
…………
}
<?php
class WatchCartoons {
…
public function __construct(ConfigFactory $config_factory) {
$this->config_factory = $config_factory;
}
…
}
The above code is an example of a .php file which is making a call to a dependency using the constructor method in the __construct() constructor for the class. In the above code, you’ll see that we named a class called WatchCartoon, which has a method that injects a service called ConfigFactory.
The code does not do anything, because it is not complete, but you can find more information at FFW. This is as far as I can take you with services, go and create your own, there is so much information about them and you can find it online for free so that you can also start to create and use services on your Drupal 8 site.
Splitting functionalities into reusable components is the idea behind a service, which can be used to accomplish many things in Drupal 8. It would be a good practice for you as a developer to create your own service or use an existing one. Creating your own service will allow you to become a master at what you just read, but if you are still unsure about this daunting task you can go on ahead and read more on the subject.
I wouldn’t suggest you start doing something in Drupal 8 if you haven’t done your research first. If you do that, then you will run into a wall, because there are things you won’t be aware off at first, when you develop your application using Drupal 8.
Thank you for reading this article!!!
\Drupal\Component\Plugin\PluginManagerInterface,Implements all plugin managers, and this piece of code extends these three pieces of code, which are the basis for any new plugin manager.
\Drupal\Component\Plugin\Discovery\DiscoveryInterface, \Drupal\Component\Plugin\Factory\FactoryInterface and, \Drupal\Component\Plugin\Mapper\MapperInterface.The plugin.manager.* a piece of code is used to generate plugin manager services and from the service container, a copy of the plugin manager can be requested. Example:
$example_manager = \Drupal::service('plugin.manager.example');Once a developer has identified the plugin manager needed, to complete a task, then that developer has to start, by locating the name of the plugin manager service he/she needs. The controller will be the place where, a developer can inject their plugin manager services, and this is the Drupal way of doing things. The code below is a controller file, located under custom_module/src/Controller, it is very important that you get those names and file directory correct, for Drupal to recognize your controller and plugin.
<?php namespace Drupal\plugin_type_example\Controller; use Drupal\Core\Controller\ControllerBase; use Drupal\plugin_type_example\SandwichPluginManager; use Symfony\Component\DependencyInjection\ContainerInterface; /** * Controller for our example pages. */ class PluginTypeExampleController extends ControllerBase { /** * The sandwich plugin manager. * * We use this to get all of the sandwich plugins. * * @var \Drupal\plugin_type_example\SandwichPluginManager */ protected $sandwichManager; /** * Constructor. * * @param \Drupal\plugin_type_example\SandwichPluginManager $sandwich_manager * The sandwich plugin manager service. We're injecting this service so that * we can use it to access the sandwich plugins. */ public function __construct(SandwichPluginManager $sandwich_manager) { $this->sandwichManager = $sandwich_manager; } /** * {@inheritdoc} * * Override the parent method so that we can inject our sandwich plugin * manager service into the controller. * * For more about how dependency injection works read https://www.drupal.org/node/2133171 */ public static function create(ContainerInterface $container) { // Inject the plugin.manager.sandwich service that represents our plugin // manager as defined in the plugin_type_example.services.yml file. return new static($container->get('plugin.manager.sandwich')); } }All defined plugins have information that can aid our application development to move forward faster. All that information from defined plugins is available to developers when they can make calls to the getDefinitions method. Enabled modules, can be used to locate all plugin definitions of the type in question, through the discovery handler . When the discovery handler is not used to retrieve data, then the DefaultPluginManager is used to retrieve the data from the cache if the data is available there. A good example of is in the code below, watch how the definitions of a plugin can be obtained in the code.
// Get the list of all the sandwich plugins defined on the system from the // plugin manager. Note that at this point, what we have is *definitions* of // plugins, not the plugins themselves. $sandwich_plugin_definitions = $this->sandwichManager->getDefinitions(); // Let's output a list of the plugin definitions we now have. $items = array(); foreach ($sandwich_plugin_definitions as $sandwich_plugin_definition) { // Here we use various properties from the plugin definition. These values // are defined in the annotation at the top of the plugin class: see // \Drupal\plugin_type_example\Plugin\Sandwich\ExampleHamSandwich. $items[] = t("@id (calories: @calories, description: @description )", array( '@id' => $sandwich_plugin_definition['id'], '@calories' => $sandwich_plugin_definition['calories'], '@description' => $sandwich_plugin_definition['description'], )); } // Add our list to the render array. $build['plugin_definitions'] = array( '#theme' => 'item_list', '#title' => 'Sandwich plugin definitions', '#items' => $items, );When a list of plugin types is desired by a developer he/she may want to use the method above to accomplish this task. The unique ID of a plugin can be utilized in order to retrieve the definition of the plugin in question, calling the getDefinition($plugin_id) method. // If we want just a single plugin definition, we can use getDefinition(). // This requires us to know the ID of the plugin we want. This is set in the // annotation on the plugin class: see \Drupal\plugin_type_example\Plugin\Sandwich\ExampleHamSandwich. $ham_sandwich_plugin_definition = $this->sandwichManager->getDefinition('meatball_sandwich'); In order to instantiate and use an individual plugin object, the createInstance($plugin_id) method can be used. It is not good practice to instantiate a plugin object directly, instead, the plugin manager should be used to do so. Understanding how instances of a plugin are created requires that you see it in action, in the code below.
// To get an instance of a plugin, we call createInstance() on the plugin // manager, passing the ID of the plugin we want to load. Let's output a // list of the plugins by loading an instance of each plugin definition and // collecting the description from each. $items = array(); // The array of plugin definitions is keyed by plugin id, so we can just use // that to load our plugin instances. $sandwich_plugin_definitions = $this->sandwichManager->getDefinitions(); foreach ($sandwich_plugin_definitions as $plugin_id => $sandwich_plugin_definition) { // We now have a plugin instance. From here on it can be treated just as // any other object; have its properties examined, methods called, etc. $plugin = $this->sandwichManager->createInstance($plugin_id); $items[] = $plugin->description(); }All the code on this tutorial was taken from Drupalize.me. Thank you for reading this article!!!
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