[wp-trac] [WordPress Trac] #53176: Block Editor: Backport the FSE infrastructure required to make the template editor work for classic themes.

[WordPress Trac]

#53176: Block Editor: Backport the FSE infrastructure required to make the template
editor work for classic themes.
----------------------------+---------------------
 Reporter:  youknowriad     |       Owner:  (none)
     Type:  task (blessed)  |      Status:  new
 Priority:  normal          |   Milestone:  5.8
Component:  Editor          |     Version:
 Severity:  normal          |  Resolution:
 Keywords:                  |     Focuses:
----------------------------+---------------------

Comment (by Bernhard Reiter):

 In Gutenberg, we're currently
 [https://github.com/WordPress/gutenberg/blob/416d1adb2ec0f46b111d5b3898859244c41f06b1/lib
 /full-site-editing/template-loader.php#L20 hooking] into all the
 [https://developer.wordpress.org/reference/hooks/type_template/
 `{type}_template`] filters.

 The overall sequence in Core looks about like this:

 * WordPress detects that the current route maps to an entity of type
 `{type}` (e.g. a `page` or `category`).
 * It calls `get_{type}_template()` (e.g. `get_page_template()`), which in
 turn passes an array of candidate template slugs (with `.php` file
 extension) to
 [https://developer.wordpress.org/reference/functions/get_query_template/
 `get_query_template()`].
 * Internally, `get_query_template()` calls, in order:
   * the
 [https://developer.wordpress.org/reference/hooks/type_template_hierarchy/
 `type_template_hiearchy`] filter, which can modify the template candidate
 list.
   * [https://developer.wordpress.org/reference/functions/locate_template/
 `locate_template`], to find the template file with the highest specificity
 that matches the candidate list.
   * the [https://developer.wordpress.org/reference/hooks/type_template/
 `type_template`] filter, which can modify that result (the path to the
 template file).

 Gutenberg only hooks into the latter filter, to "redirect" WordPress to
 its special `template-canvas.php` template file, which will render the
 best matching block template (if any). The reason for this is that WP
 expects a (PHP) file _path_ -- and in GB, we can't guarantee that there's
 always a template file, since block templates can also come from a
 `wp_template` post object.

 OTOH, it means that Gutenberg is conflating concerns within that filter,
 rather than aligning them within the framework of e.g.
 `get_{type}_template()` and `locate_template()`.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/53176#comment:2>
WordPress Trac <https://core.trac.wordpress.org/>
WordPress publishing platform