How to change a constructor argument's value with the depenency injection?

dmitry_fedyuk · November 15, 2015, 5:50am

Let’s see the class \Magento\Framework\Config\Reader\Filesystem.

It has a constructor argument domDocumentClass:

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/lib/internal/Magento/Framework/Config/Reader/Filesystem.php#L89


 * @param string $domDocumentClass
 * @param string $defaultScope
 */
public function __construct(
    \Magento\Framework\Config\FileResolverInterface $fileResolver,
    \Magento\Framework\Config\ConverterInterface $converter,
    \Magento\Framework\Config\SchemaLocatorInterface $schemaLocator,
    \Magento\Framework\Config\ValidationStateInterface $validationState,
    $fileName,
    $idAttributes = [],
    $domDocumentClass = 'Magento\Framework\Config\Dom',
    $defaultScope = 'global'
) {
    $this->_fileResolver = $fileResolver;
    $this->_converter = $converter;
    $this->_fileName = $fileName;
    $this->_idAttributes = array_replace($this->_idAttributes, $idAttributes);
    $this->validationState = $validationState;
    $this->_schemaFile = $schemaLocator->getSchema();
    $this->_perFileSchema = $schemaLocator->getPerFileSchema() && $validationState->isValidationRequired()
        ? $schemaLocator->getPerFileSchema() : null;

The default domDocumentClass value is Magento\Framework\Config\Dom.

It is used here:

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/lib/internal/Magento/Framework/Config/Reader/Filesystem.php#L136


 * @return array
 * @throws \Magento\Framework\Exception\LocalizedException
 */
protected function _readFiles($fileList)
{
    /** @var \Magento\Framework\Config\Dom $configMerger */
    $configMerger = null;
    foreach ($fileList as $key => $content) {
        try {
            if (!$configMerger) {
                $configMerger = $this->_createConfigMerger($this->_domDocumentClass, $content);
            } else {
                $configMerger->merge($content);
            }
        } catch (\Magento\Framework\Config\Dom\ValidationException $e) {
            throw new \Magento\Framework\Exception\LocalizedException(
                new \Magento\Framework\Phrase("Invalid XML in file %1:\n%2", [$key, $e->getMessage()])
            );
        }
    }
    if ($this->validationState->isValidationRequired()) {

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/lib/internal/Magento/Framework/Config/Reader/Filesystem.php#L173


/**
 * Return newly created instance of a config merger
 *
 * @param string $mergerClass
 * @param string $initialContents
 * @return \Magento\Framework\Config\Dom
 * @throws \UnexpectedValueException
 */
protected function _createConfigMerger($mergerClass, $initialContents)
{
    $result = new $mergerClass(
        $initialContents,
        $this->validationState,
        $this->_idAttributes,
        null,
        $this->_perFileSchema
    );
    if (!$result instanceof \Magento\Framework\Config\Dom) {
        throw new \UnexpectedValueException(
            "Instance of the DOM config merger is expected, got {$mergerClass} instead."
        );

Let’s try to change the Magento\Framework\Config\Dom to a custom class for a particular \Magento\Framework\Config\Reader\Filesystem descendant: Magento\Config\Model\Config\Structure\Reader

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/app/code/Magento/Config/Model/Config/Structure/Reader.php#L18


*/
namespace Magento\Config\Model\Config\Structure;


use Magento\Framework\DataObject;
use Magento\Framework\Exception\LocalizedException;
use Magento\Framework\View\TemplateEngine\Xhtml\CompilerInterface;


/**
* Class Reader
*/
class Reader extends \Magento\Framework\Config\Reader\Filesystem
{
   /**
    * List of identifier attributes for merging
    *
    * @var array
    */
   protected $_idAttributes = [
       '/config/system/tab' => 'id',
       '/config/system/section' => 'id',
       '/config/system/section(/group)+' => 'id',

My dependency injection code:

<type name='Magento\Config\Model\Config\Structure\Reader'>
	<arguments>
		<argument name='domDocumentClass' xsi:type='string'>Df\Framework\Config\Dom</argument>
	</arguments>
</type>

See http://devdocs.magento.com/guides/v2.0/extension-dev-guide/depend-inj.html#dep-inj-preview-cons