Conflict with Redirect module, impossible to edit Canvas page

This is critical for Drupal CMS, which has both modules and suffers from this with Canvas HEAD.

I think this is a beta blocker, but might be wrong.

Did the same thing ~8 years ago in #2924916: Compatibility with contrib Redirect module: disable language redirects for CDN's "farfuture" route for the CDN module I maintain, and did so with this comment:

…
  defaults:
    _controller: Drupal\cdn\CdnFarfutureController:download
    # Ensure the redirect module does not redirect to add a language prefix.
    # @see \Drupal\redirect\EventSubscriber\RouteNormalizerRequestSubscriber
    # @todo Update this comment when https://www.drupal.org/project/drupal/issues/2641118 lands.
    _disable_route_normalizer: TRUE
…

However that route was for serving file assets which are the same in all contexts, including all translations. Wheras the Canvas module will eventually need to become multilingual. So … won't this get in the way? 🤔

I think the answer is "no, this won't get in the way". Because this MR is setting _disable_route_normalizer in the inbound path processor instead of the route definition.

If @penyaskito can confirm that understanding, then merge away! 😄

P.S.: https://www.hashbangcode.com/article/drupal-10-creating-custom-paths-pat... was quite helpful for this! 😊

Correct. For the record, e.g. /es/canvas works in the same way than before this patch (which is not usable at all, but we aren't making it harder than it already is)

Merged! 🎉

Verified the scenarios described below:

Steps followed:

Install the module using the following commands:

• ddev composer require drupal/redirect
• ddev drush en redirect

Attached the screenshot of the UI for the redirect module page:

@penyaskito, can you investigate the 3 failures reported by @mayur-sose? 🙏

After more testing I cannot reproduce the mentioned problems consistently, but definitely there's some issue here.

E.g. if I go to page 2 it works, if I go to page 3 it doesn't, clearing cache fixes it but eventually I hit it again for some page (but not all of them).

@penyaskito Please check screen record :

Could it be a race condition in client-side routing? 🤔

I fail to see why this could be a client-side issue, as only happens with redirect module enabled, but debugged this and our path processor is always hit (even when the bug happens), so has to be client-side.

I could reproduce this with canvas_vite enabled, and tried to debug AppRoutes.tsx, but couldn't see anything different in the router object, and I'm not very aware how the react app routing works.
Might need help from the FE team to move forward.

Just after posting that decided to read again https://www.hashbangcode.com/article/drupal-10-creating-custom-paths-pat..., and moved the logic to an event subscriber. I cannot reproduce the bug, but this was only manual testing and as we couldn't reproduce consistently, we cannot 100% guarantee we fixed it.

But I did enough back-and-forth testing to think this solves it.

IMHO can be both faster (use RoutingEvents::ALTER) and simpler (str_starts_with($route_name, 'canvas.').

Resolved all review points.

LGTM! I'm assuming @penyaskito did the necessary manual testing :)

Suggested commit message:

[#3546600] fix: Conflict with Redirect module, impossible to edit Canvas page

By: penyaskito
By: wim leers
By: mayur-sose

Needs to get recent 1.x commits merged in before this can be merged.

Reported issues are now resolved and changes are working as expected.

Problem still persist if try to use Canvas on multilingual site.

If Language module is activated and used (default and logical) option with prefixes for choosing interface language.

And you add one or more interface languges.

Canvas editor will not work

See #3546597: Create Canvas pages in any enabled content language.