Magento 2 Dependency Injection and Relevant Information

Until now, I’m sure that all of the Magento 1 users have moved their stores to Magento 2 already. To work with Magento 2, it’s necessary to use Magento 2 Dependency injection that is used to replace Magento 1.x Mage class.

The Dependency injection design pattern creates an external environment where you can inject dependencies into an object. Thanks to that, you will no longer have to create the objects manually. Namely, as when object A calls object or value B, this means B is a dependency of A.

Magento 2 Dependency Inversion Principle

If you are working with Magento 2 Dependency Injection, you should take look at Magento 2 Dependency Inversion Principle because this principle will restrict the direct working between the high level and low level classes. At that time, the interaction will implement via an interface of the low level classes as an abstract layer.

Specifically, the di.xml file takes responsibility for mapping an interface dependency to a preferred implementation class. It can be said that with Magento 2 Dependency Inversion Principle, the dependency of the coding will be reduced significantly due to the abstract layer.

Object manager - Dependency Injection Container

Object Manager is called as Dependency Injection Container, Magento 2 service class which contains and handle the dependencies between the objects. During the class construction, the object manager injects the appropriate dependency as defined in the di.xml file.

Constructor signature dependencies

In Magento 2, the class definition use constructor signature to get information (type and number of dependencies).

Compiling dependencies

All information related to Magento 2 Dependency Injection are collected in a class and saved in files by a code complier tool. And then the ObjectManager will get this information to generate concrete objects in the application.

Injection types used in Magento 2

Magento 2 Dependency Injection includes two types: Constructor Injection and Method Injection. You can see the following code snippet to learn more about both of them.

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 the above example, $menuItemFactory and $menu are the dependencies that will be added to an object’s class through the constructor injection. Besides, remember that the constructor injection is required to declare all optional and required of an object.

Method injection

About Method Injection, you will use it when an object makes clear a dependency in one of its methods. As if tracking in the referred instance, $command is the dependency passed into the class through the processCommand method.

Groups of Object

In Magento 2, the object is divided into two groups: injectable and non-injectable (newable) objects. What are they?

Injectable Objects

About the injectable Objects, you can call as services or objects which will show the dependencies in their constructors and are created by the object manager via the configuration in the di.xml file. And you can use these injectable objects to request other injectable services in the constructors.

Non-injectable Objects

Non-injectable (Newable) Objects are a bit similar to the injectable objects when they also expose the dependencies in their constructors, however, the newables are allowed to request other newables objects like Entities, Value Objects. In addition, you cannot demand the newable objects for keeping a reference to an injectable object.

This is the detailed information related to Magento 2 Dependency Injection design pattern. Wish you have a great time with it!

Image Optimizer

Image Optimizer for Magento 2

Speed up page loading & enhance the user experience for your store

Check it out!

Related Topics

Image Description
With over a decade of experience crafting innovative tech solutions for ecommerce businesses built on Magento, Jacker is the mastermind behind our secure and well-functioned extensions. With his expertise in building user-friendly interfaces and robust back-end systems, Mageplaza was able to deliver exceptional Magento solutions and services for over 122K+ customers around the world.

People also searched for

  • magento 2 dependency injection
  • dependency injection in magento 2
  • 2.3.x, 2.4.x