Magento 2 Dependency Injection

May 10, 2021 The Online Helper

Magento 2 Dependency injection is utilized to substitute the Magento 1.x Mage class when you transform work with Magento 2. The Dependency injection design pattern forms an external circumstance where you can inject dependencies into a thing. There is no longer to produce the objects manually. Namely, when object A requests object or value B, this indicates B is a dependency of A.

Magento 2 Dependency Inversion System

If you are already working with Magento 2 Dependency Injection, you should look at Magento 2 Dependency Inversion System because this system will restrict the straight working among the high-level and low-level classes. At that time, the interaction will perform via an interface of the low-level classes as an abstract.

Particularly, the di.xml file operates the responsibility for mapping an interface dependence to a supported implementation class. We can say that with Magento 2 Dependency Inversion System, the dependency of the coding will be decreased significantly due to the abstract layer.

Object manager in Dependency Injection

Object Manager is known as Dependency Injection Container, Magento 2 service class which includes and controls the dependencies between the objects. During the class construction, the object manager injects the proper dependency as described in the di.xml.

Constructor dependencies

In Magento 2, the class description uses a constructor signature to get data (number of dependencies type and type).

Compiling the dependencies

All data related to Magento 2 Dependency Injection is gathered in a class and stored in files by a code compiler. And then the ObjectManager will receive this data to create concrete objects.

Injection types utilized in Magento 2

Magento 2 Dependency Injection involves two types:

Constructor Injection
Method Injection.

namespace Magento\Backend\Model\Menu;

class Builder

{

    /**

     * @param \Magento\Backend\Model\Menu\Item\Factory $menuItemFactory

     * @param \Magento\Backend\Model\Menu $menu

     */

    public function __construct(

        Magento\Backend\Model\Menu\Item\Factory $menuItemFactory, // Service dependency

        Magento\Backend\Model\Menu $menu // Service dependency

    ) {

        $this->_itemFactory = $menuItemFactory;

        $this->_menu = $menu;

    }




    public function processCommand(\Magento\Backend\Model\Menu\Builder\CommandAbstract $command) // API param

    {

        // processCommand Code

    }

}

Constructor injection

As an example, $menuItemFactory and $menu are the dependencies that will be calculated to an object’s class by the constructor injection. Moreover, recognize that the constructor injection is needed to represent all optional and required of an object.

Method injection

You will utilize it if an object makes clear a dependency in one of its methods. As if following in the mentioned case, $command is the dependency reached into the class by the process command method.

Groups of Object

In Magento 2, the object is split into two different groups:

injectable
non-injectable (renewable) objects.

Injectable Objects

You can command assistance or objects which will display the dependencies in their constructors and are produced by the object manager via the configuration in the di.xml file. And you can utilize these injectable objects to demand other injectable assistance in the constructors.

Non-injectable Objects

Non-injectable (Newable) Objects are a bit related to the injectable objects when they further reveal the dependencies in constructors, nevertheless, the renewables are supported to demand other renewables objects like Items, Value Objects. Additionally, you cannot claim renewable objects for having a recommendation to an injectable object.

If you are looking for Magento 2 Developers, visit Magento 2 Services.