Receiving object specific class which was injected in constructor by three-part extension

Question

For example, anybody can modify this virtual type magento/module-catalog/etc/di.xml:

<virtualType name="Magento\Catalog\Model\Layer\Search\Context" type="Magento\Catalog\Model\Layer\Context">
    <arguments>
        <argument name="collectionProvider" xsi:type="object">Magento\Catalog\Model\Layer\Search\ItemCollectionProvider</argument>
        <argument name="stateKey" xsi:type="object">Magento\Catalog\Model\Layer\Category\StateKey</argument>
        <argument name="collectionFilter" xsi:type="object">Magento\Catalog\Model\Layer\Search\CollectionFilter</argument>
    </arguments>
</virtualType>

Let's assume that instead

Magento\Catalog\Model\Layer\Search\ItemCollectionProvider  

now

Vendor\Name\Model\Layer\Search\ItemCollectionProvider

When I implement virtual type (Magento\Catalog\Model\Layer\Search\Context) in own class constructor I get fatal error:

Class Magento\Catalog\Model\Layer\Search\Context does not exist

It seems, that using of virtual types is allowed only in di.xml

I can inject in own class the class which use this context, but context is the protected property and i can't get it.

How I can find class Vendor\Name\Model\Layer\Search\ItemCollectionProvider from any place of code?

Answer 1

The configurations declared via virtualType are not sub-classes of base class.

Virtual types with class-similar names add some confusion in this problem.

You need to perceive "virtual types" as configured instances of base class.

Example:

di.xml

<virtualType name="LetterA" type="Magento\Framework\Alphabet\CharacterInterface">
    <arguments>
        <argument name="symbol" xsi:type="string">A</argument>
    </arguments>
</virtualType>
<virtualType name="LetterB" type="Magento\Framework\Alphabet\CharacterInterface">
    <arguments>
        <argument name="symbol" xsi:type="string">B</argument>
    </arguments>
</virtualType>

<type name="Magento\Framework\Alphabet\CharacterListInterface">
    <arguments>
        <argument name="characters" xsi:type="array">
            <item name="a" xsi:type="object">LetterA</item>
            <item name="b" xsi:type="object">LetterB</item>
        </argument>
    </arguments>
</type>

This configuration in PHP code without DI looks like:

$a = new Character('A');
$b = new Character('B');

$list = new CharacterList([
    'a' => $a,
    'b' => $b
]);

Pay attention to this - only class instances, without subtypes of Character.

---

In your case, if you need to inject virtual types object in your constructor, you need to inject the virtual type's base type and add type-preference to di.xml special for your class.

Example:

MyClass.php

class MyClass
{
    /**
     * @param \Magento\Catalog\Model\Layer\Context $context
     */
    public function __construct(\Magento\Catalog\Model\Layer\Context $context)
    {
        $this->context = $context;
    }
}

di.xml

<type name="Vendor\Name\Model\MyClass">
    <arguments>
        <argument name="context" xsi:type="object">Magento\Catalog\Model\Layer\Search\Context</argument>
    </arguments>
</type>

So the virtual type will be injected in your class.