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Factories

Overview

Factories are service classes that instantiate non-injectable classes, that is, models that represent a database entity . They create a layer of abstraction between the ObjectManager and business code.

Relationship to ObjectManager

The Magento\Framework\ObjectManager is the class responsible for instantiating objects in the Magento application. Magento prohibits depending on and directly using the ObjectManager in your code.

Factories are an exception to this rule because they require the ObjectManager to instantiate specific models.

The following example illustrates the relationship between a simple factory and the ObjectManager:

namespace Magento\Framework\App\Config;

class BaseFactory
{
  /**
   * @var \Magento\Framework\ObjectManagerInterface
   */
  private $_objectManager;

  /**
   * @param \Magento\Framework\ObjectManagerInterface $objectManager
   */
  public function __construct(\Magento\Framework\ObjectManagerInterface $objectManager)
  {
    $this->_objectManager = $objectManager;
  }
  /**
   * Create config model
   * @param string|\Magento\Framework\Simplexml\Element $sourceData
   * @return \Magento\Framework\App\Config\Base
   */
  public function create($sourceData = null)
  {
    return $this->_objectManager->create(\Magento\Framework\App\Config\Base::class, ['sourceData' => $sourceData]);
  }
}

Writing factories

Unless you require specific behavior for your factory classes, you do not need to explicitly define them because they are an automatically generated class type. When you reference a factory in a class constructor, Magento’s object manager generates the factory class if it does not exist.

Factories follow the naming convention <class-type>Factory where <class-type> is the name of the class the factory instantiates.

For example the automatically generated Magento\Cms\Model\BlockFactory class is a factory that instantiates the class Magento\Cms\Model\Block.

Using factories

You can get the singleton instance of a factory for a specific model using dependency injection.

The following example shows a class getting the BlockFactory instance through the constructor:

function __construct ( \Magento\Cms\Model\BlockFactory $blockFactory) {
    $this->blockFactory = $blockFactory;
}

Calling the create() method on a factory gives you an instance of its specific class:

$block = $this->blockFactory->create();

For classes that require parameters, the automatically generated create() function accepts an array of parameters that it passes on to the ObjectManager to create the target class.

The example below shows the construction of a Magento\Search\Model\Autocomplete\Item object by passing in an array of parameters to a factory:

$resultItem = $this->itemFactory->create([
  'title' => $item->getQueryText(),
  'num_results' => $item->getNumResults(),
]);

Interfaces

Factories are smart enough to resolve dependencies and allow you to get the correct instance of an interface as defined in your module’s di.xml.

For example, in the CatalogInventory module, the di.xml file contains the following entry:

<preference for="Magento\CatalogInventory\Api\Data\StockItemInterface" type="Magento\CatalogInventory\Model\Stock\Item" />

It instructs Magento to use the specific Item class wherever the StockItemInterface is used. When a class in that module includes the factory StockItemInterfaceFactory as a dependency, Magento generates a factory that is capable of creating the specific Item objects.