Magento 2 – Access Helper Without Constructor Injection

best practicedependency-injectionhelpermagento2

Is there a clean way to initiate and access a custom helper without using the constructor? Currently I instantiate the custom helper using the constructor of the model as shown here as the accepted answer.

This is great in most cases but now I would like to access a helper method on a model that adds a bit of functionality to the product model – extending \Magento\Catalog\Model\Product. It seems a bit overkill to overwrite this constructor so I am wondering if there is an alternative, acceptable way to do this? Can I just grab it directly via the ObjectManager or roll out my own factory like @philwinkle suggested here or is this not recommended?

Best Answer

the clean way to do it is to inject it in the constructor. Exactly what you are trying to avoid.
Also it can work if you instantiate it via objectManager, but this is discouraged. Even if there are classes instantiated via object manager in the core, this is not the recommended way to do it.
I'm not 100% sure, but I think the suggestion you mention from @philwinke is not valid anymore. That was for an older version. A lot has changed since then.
But even so, if you want to instantiate it via a helper factory, you still need to inject the helper factory in the constructor.
My recommendation is to inject it in the constructor, but if you absolutely don't want that, and you have an instance of the object manager available, instantiate it via object manager.

Related Solutions

Magento2 Unit Testing – Use Object Manager

The object manager for unit tests is in magento/framework/TestFramework/Unit/Helper/ObjectManager.php and you obviously instantiated it, otherwise you would not get this error message. But you are using it wrong, it does not have a create() method. As explained in the linked answer, you need getObject():

public function getObject($className, array $arguments = [])

I am using the ObjectManager::create method to get an Instance of my Helper class in another custom class. So i shouldnt use ~::create at all?

Not with this object manager helper for unit tests. It has a different interface than the regular object manager. It sounds like you are passing the unit test object manager to a class under test. This is not how it is intended to be used.

In an integration test you can use: Magento\TestFramework\ObjectManager::getInstance() which works like the "real" object manager. In a unit test, you could instantiate or mock the real object manager Magento\Framework\App\ObjectManager.

But the fact that you need it, tells you that there's something wrong. Don't use the object manager to get an instance of your helper. Instead, add your helper as a constructor parameter and let Magento handle the Dependency Injection.

Magento2 Best Practices – Using ObjectManager Directly

You should not use the ObjectManager directly!

Exception from the rule are:

in static magic methods like __wakeup, serialize, etc
in case you should make backward compatibility of constructor
in global scope, like in fixtures of integration test.
in class that needs only for creation of object like factory, proxy , etc

Best Answer

Related Solutions

Magento2 Unit Testing – Use Object Manager

Magento2 Best Practices – Using ObjectManager Directly

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