mjhjmtu

What is difference on both and how will i understand to where should i use any one of these ?

MagentoFrameworkObjectManagerInterface

MagentoFrameworkAppObjectManager::getInstance()

if i use

MagentoFrameworkAppObjectManager

In constructor then.

There is no difference between use of ObjectManagerInterface and ObjectManager class. As When you use ObjectManagerInterface it will give instance of ObjectManager class.

MagentoFrameworkAppObjectManager
MagentoFrameworkObjectManagerInterface

But You should never use ObjectManager directly in the code. It will Automatically come in use when we specify Factory Classes in constructor.

If due to some application constraints, you need to use ObjectManager then use ObjectManagerInterface in constructor.

First you must know what are interfaces?

• Interfaces are 100% abstract classes – they have methods but the methods have no ‘guts’




• Interfaces cannot be instantiated – they are a construct in OOP that allows you to inject ‘qualities’ into classes .. like abstract classes.



• Where an abstract class can have both empty and working/concrete methods, interface methods must all be shells – that is to say, it must be left to the class (using the interface) to flesh out the methods.

Below reference will guide when to use interface and when to direct class.

when and why you should use them instead of classes

Using in constructor is a better choice then the other way, as you are injecting it into the class.

The other way is also used but it is not good. I use the other way only when i am overriding a class which has many injected classes, so if i inject my new class in the child class then i have to override the contructor of parent class. which means i have to inject all classes in parent also in classed and call the parent class. So to avoid this i use object mangener.

You should use the interface

MagentoFrameworkObjectManagerInterface

as Magento has mechanism called Dependency injection. This is originally provided by symfony/dependency-injection package - look it up in your composer.lock file.

In effect the dependency injection mechanism will locate that actual class that implements the given interface. You need not to worry which is the actual class that gets instantiated.

For example, each module will define a preference for a given interface.

Lets take a look at file /vendor/magento/module-wishlist/etc/di.xml

There is a code like

<preference for="MagentoWishlistModelAuthenticationStateInterface" type="MagentoWishlistModelAuthenticationState" />

which means that if you try to inject MagentoWishlistModelAuthenticationStateInterface in some of your class, Magento will make sure you get instance of MagentoWishlistModelAuthenticationState

And if for some reason you are not happy with the default class used, you can always tell magento to use another class in you module /etc/di.xml file.