Magento 2 override core Model class with psr-4 by replacing in app/code/Magento

Question

"autoload": {
        "psr-4": {
            "Magento\\Framework\\": "lib/internal/Magento/Framework/",
            "Magento\\Setup\\": "setup/src/Magento/Setup/",
            "Magento\\": "app/code/Magento/"
        },
        "psr-0": {
            "": "app/code/"
        },
        "files": [
            "app/etc/NonComposerComponentRegistration.php"
        ]
    },

This is composer autoload part from composer.json on magento2 root

as per this i have successfully overirde

vendor/magento/framework/View/Element/Html/Link.php

by replacing this file in

lib/internal/Magento/Framework/View/Element/Html/Links.php

Now i have tried same for

vendor/magento/module-catalog-import-export/Model/Import/Product/Validator/Media.php

By replacing this file in

app/code/Magento/CatalogImportExport/Model/Import/Product/Validator/Media.php

above override method is not working.can anyone point me in right direction ?

PS : i want to change const URL_REGEXP = '|^http(s)?://[a-z0-9-_]+(.[a-z0-9-_]+)*(:[0-9]+)?(/.*)?$|i'; of above class as it cause issue in product import which has double underscore in image url

Can i override using psr-4 or not ? I do not want to go for "preference" if above solution fix my issue.

Answer 1

As described here, you can override single classes by (ab)using composer autoload definitions like this:

  "files": ["app/code/Magento/CatalogImportExport/Model/Import/Product/Validator/Media.php"]

But just because you can, does not mean you should. Always prefer plugins if possible, and fall back to DI preferences if not. There are very rare cases where a hack like this is really necessary.

Regarding your concrete issue: while you cannot override a constant using preferences, you can override its usages. In Magento 2.1 this constant is only used once, in Magento\CatalogImportExport\Model\Import\Product\Validator\Media::checkValidUrl(). Since it is a protected method, you cannot write a plugin for it, but you can replace the class using preferences with:

class MediaValidator extends Magento\CatalogImportExport\Model\Import\Product\Validator\Media
{
    const URL_REGEXP = '|^http(s)?://[a-z0-9-]+(.[a-z0-9-]+)*(:[0-9]+)?(/.*)?$|i'; // <-- change this line

    protected function checkValidUrl($string)
    {
        return preg_match(self::URL_REGEXP, $string);
    }
}

Here, self refers to the new class instead of the parent class.

And just for your info, in Magento 2.2 this method is not used anymore and marked as deprecated:

 * @deprecated As this method doesn't give a guarantee of correct URL validation.
 * @see \Magento\Framework\Url\Validator::isValid() It provides better URL validation.

Answer 2

TL;DR: You can't use PSR-4 autoload in composer.json file. Every modules in Magento 2 have their own autoload, that's useless unless you are using the source code from Magento 2 Github repo.

magento/framework ("lib/internal/Magento/Framework/") and magento/magento2-base ("app/code/Magento"), actually, have their autoload.

The reason why Git repository (magento/magento2) is that it includes whole Magento and so does not download components (such as Framework) via Composer. That's why composer.json of the Git repository includes duplicated information to let Composer read and process it.