RequestRouter: POST Requests - Process POST request inside admin_init

[nicolas-jaussaud]

Hi @zinigor!

It looks like there is a small issue with the way we handle POST request currently

Every DataView request is processed inside a menu or submenu render callback (here)

It causes issues for POST requests because they trigger a redirection, and as we have already rendered content at this point it triggers the following error and the redirection fails:

Warning: Cannot modify header information - headers already sent by (output started at /var/www/html/tobet/wp-includes/fonts/class-wp-font-face.php:98) in /var/www/html/tobet/wp-includes/pluggable.php on line 1535

See associated screencast:
https://github.com/user-attachments/assets/b8a89d61-b4ad-4784-8022-2daf7ea6d344

As a fix, I moved POST request handling in a separate method called maybe_redirect(), which will be triggered earlier during admin_init

[zinigor]

Yeah, this makes sense, but I think it will need some work after the Request PR is merged, wouldn't it?

[nicolas-jaussaud]

Ah yes indeed!

We'll need to replace $this->is_post(), $this->url_builder->get_current_action() and $this->url_builder->get_current_id()

I'll merge the other PR first, merge the changes from main on this branch and replace what's needed before merging