Magento 2 has many changes but one of the biggest changes is the use of dependency injection. Let’s start with the definition of these terms as we know many will not be fluent in programming languages! The dependency is the object which is utilised by a class to allow it to carry out certain functions. The injection is the part that passes this dependency to the dependent class or object. Therefore, when we talk about dependency injection we are simply referring to the injection of a dependency into a class or object from another source!
The Benefits of Dependency Injection in Magneto 2
Much of the coding that is used in programmes is not as up to date and effective as it possibly could be and this is where dependency injections for Magento 2 come into play. Using dependency injections can solve many issues and save you from lengthy and tedious processes, particularly with larger applications. Using dependency injections in long term projects allows for more maintainable code.
Using Object Manager in Magento 2
One of the downsides to dependency injection is that is can make your coding much, much larger! This can then mean that it is harder to debug the code. There is a way around this, however, and that is through ObjectManager. With larger projects, the use of dependency injection also introduces dependency injection container which is the ObjectManager. This will be responsible for determining and producing dependencies upon object creation. Some would argue, however, against using ObjectManager as it defeats the purpose of Dependency Injection. While using ObjectManager allows you to write less code, it does not follow the Magento 2 Development Processes and can create hidden dependencies that are not required!
Injectable and Non-Injectable Objects in Magneto 2
In Magneto 2, there are two groups of objects that we can discuss and this is injectable and non-injectable objects.
Non-injectable objects are simply objects that have an identity, for example, this could be orders, cart items, users and so on so forth. If you want to use non-injectable items in your code you must request their factory. An example of this could be trying to load numerous products. Your code then will be subject to product factory and with that object you would use the ObjectManager method for the identity of the products that you are trying to load.
Injectable objects, on the other hand, will show the dependencies in their constructors. You can form them using the object manager and configuration in the di.xml file. You can also use their injectable objects to demand other injectable facilities in the constructors.
This is the basics of dependency injection usage with Magento 2. It is extremely important to follow the code patterns while doing development and, overall, the Magento community highly recommends that you use Dependency Injection