How do I find out where a specific route goes?

Question

In once place, I have a /Vendor/Module/etc/routes.xml, showing:

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
    <router id="standard">
        <route id="categories" frontName="categories">
            <module name="Vendor_Module" />
        </route>
    </router>
</config>

which points to a valid (as far as I can see) controller. (Index/Index, to be precisely. )

In the database, table mg_url_rewrite, "categories" is pointed towards catalog/product/view/id/.

How can I figure out where a request for www.mysite.com/categories actually goes?

My instinct says the routes.xml file, but an exact duplicate of that controller in another module shows an empty page, where .../categories actually shows the categories of the webshop. All the controller does is:

public function __construct(Context $context, PageFactory $resultPageFactory)
    {
        $this->resultPageFactory = $resultPageFactory;
        parent::__construct($context);
    }

public function execute()
    {
        $resultPage = $this->resultPageFactory->create();
        $resultPage->getConfig()->getTitle()->prepend(__('Categories'));
        return $resultPage;
    }

But the page doesn't even have a title, which the other (controller exact duplicate except from namespaces, and same for the routes.xml except ofcourse for the Vendor_Module, route id and frontname) module does.

However, if I manually enter the url provided by the mg_url_rewrite table, I get a 404.

Answer 1

The UrlRewrite Module. And so the urlrewrite rules use an additinoal entry inside the routerList. This entry has the sort order of 20.

    <type name="Magento\Framework\App\RouterList">
        <arguments>
            <argument name="routerList" xsi:type="array">
                <item name="urlrewrite" xsi:type="array">
                    <item name="class" xsi:type="string">Magento\UrlRewrite\Controller\Router</item>
                    <item name="disable" xsi:type="boolean">false</item>
                    <item name="sortOrder" xsi:type="string">20</item>
                </item>
            </argument>
        </arguments>
    </type>

This routerlist is traversed inside the Magento\Framework\App\FrontController. The first one which matched your route is used.

Before the urlRewrite only the RouterList of the module-robots is used.

So I would guess that url-rewrite takes precendence before routes.xml, but i didn't dig further into it yet.

*edit:
What checks for the routes.xml inside the frontend is not the default router. But the standard router, which is also defined in the module-store di.xml and is located in. Magento\Framework\App\Router\Base. This one has a sort order of 30 and is processed directly after the url-rewrites.

The default router which is also defined in module-store, is only for processing the no-route pages.