Check if $node is a node object

Upcasting depends on the type hints of the controller/form.

Things are only upcasted if the "target" has a matching interface, so if you define a route with {node}, if you use "NodeInterface $node" in your controller, then you get an upcasted node object, if you just have "$node", then you just get the ID.

If you have generic code that just accesses a route parameter based on the name, then you don't know what is the case.

Another thing, the correct way to access it would be \Drupal::routeMatch()->getParameter('node') (see https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Core%21Routing%2...), but I think the behavior is the same.

That's what I tried before :)

Let's say you have two routes (more or less made up):

/node/{node} => NodeController::view(NodeInterface $node)

and

/whatever/{node} => WhateverController::doSomething($node)

Then you access it with node/1 vs. whatever/1.

For node/1, the routing/upcasting system automatically loads node 1 and the parameter that is passed around from then on is a Node entity object. for whatever/1, this doesn't happen, and $request->attributes->get('node') or \Drupal::routeMatch()->getParameter('node') is just "1".

Now, if your code runs on such a page, it current fails. I think I've seen this on the confirmation page for reverting a revision, which has this route "/node/{node}/revisions/{node_revision}/revert". Because it never actually uses {node}, it is also not upcasted. So just create a revision of a node, and then try to revert that and you should see some errors.

Because of what I just explained, twice? It is only upcasted when the controller requests an object with a type hint.

Why do you want another way, one is enough?

This tells me we are running a node:

No. That is *not* what it means.

It means you are on a route with a parameter {node}.

That is *just* a name. It could be anything. You can define a route '/whatever/{node}' and call it with whatever/banana. Technically, that is perfectly fine.

Now, there is a bit of magic, that for example for node/1, converts the route parameter {node} with the value '1' into a Node object. That magic is called upcasting (or sometimes parameter converting). That magic works by default*, under one condition: The controller for that route must type hint with NodeInterface, or at least EntityInterface, only then this happens.

* It works by default, but it is also configurable. You can load a {node} as a user, or a {whatever} as a node (sometimes, you want to load two different nodes in a route, but you can only have one {node}, this is why). See paramconverter_test.routing.yml for some fun examples.

Basically, this is the same as % and %node in D7, except that there are some more conditions now and it is more flexible/configurable.

And all of this is why you need to check if $node is actually a node entity. Because someone might have created a route where {node} is 'banana', just to mess with your head.

No, I meant to I tried to explain it before. The patch is fine.