Themes should support uninstall.php or uninstall hook

[WraithKenny]

Related tickets on extending Themes to have Plugin features: #7795 and #14849 but those deal primarily with activation and deactivation centering around 'switch_themes' action.

From looking at /wp-admin/includes/plugin.php, adding support for uninstall is a separate concern (and it doesn't have the issue blocking activation/deactivation).

Should is_uninstallable_plugin, register_uninstall_hook and uninstall_plugin be extended to check theme directory or should versions (is_uninstallable_theme, register_uninstall_theme_hook and uninstall_theme) be added to theme.php?

Advantage of the first method is that the register_uninstall_hook could be reused for Themes where in the second, a new, less attractive name would be needed (register_uninstall_theme_hook?) Also, there's no theme_basename as it was reverted/removed.

[scribu]

We shouldn't attempt to reuse register_*_hook() functions because there's only one theme running at a time, so the underlying logic would be very different.

That's why there's no theme_basename() and why the $file parameter wouldn't be needed.

[scribu]

Forget what I said, as it doesn't apply to the uninstall process.

[scribu]

Related: #7795

(duh, it's in the ticket description)

[chipbennett]

So, at Scribu's prompting, I'm going to attempt to create a patch for this. I'm thinking of creating analogous functions in themes.php, unless either of you think I should go the route of extending the existing Plugin hooks?

(Should I assign this to myself? I am still mostly unfamiliar with Trac workflow.)

[scribu]

You can assign it to yourself, if you want, but it's not mandatory.

Extending register_uninstall_hook() is not an option.

The available options are:

• uninstall.php file
• register_theme_uninstall_hook()

[greuben]

Instead of register_theme_uninstall_hook() we can use 'uninstall_theme' hook.

14955.diff​ makes use of uninstall.php and introduces 'uninstall_theme' hook.

[DrewAPicture]

#19505 closed as duplicate.

[oncletom]

Any progress on this topic?

[obenland]

Refreshed patch

[c3mdigital]

Related: #16401

[nacin]

This doesn't seem like functionality I'd want themes to have.

[WraithKenny]

@nacin Theme's can add options, create tables, and do all sorts of things that plugins can do, but has little opportunity to clean up after themselves. Shouldn't themes clean up like plugins are expected to?

[helen]

Replying to nacin:

This doesn't seem like functionality I'd want themes to have.

[Apiweb]

As the WraithKenny said, has many themes that add tables, alter the structure of WordPress, and with all the powerful API of WordPress they can do a lot more, I believe this would be an interesting option to be implemented.

[chriscct7]

#16401 was marked as a duplicate.

[kjodle]

Some themes are doing this already. It would be beneficial to keep the database clean, and to ensure that all themes are doing this in a uniform way. Perhaps as all themes migrate to using the customizer, this can be implemented.

[muxahuk1214]

Any progress on this topic? May be you could implement only do_action for now ?

[swissspidy]

#37951 was marked as a duplicate.

[vetyst]

v4.6 deleted_theme hook

[vetyst]

I would really want this feature to be implemented aswell, I had a round about way for catching theme deletions before by checking if the script wp-admin/theme.php was used. Unfortuanetly since 4.6 this no longer works as everything goes through ajax.

A simple hook would be sufficient as profided in 14955.2.patch!

[swissspidy]

#38001 was marked as a duplicate.

[okvee]

I have a very simple theme that has no feature, just index.php style.css and screenshot.png.

WordPress have customizer and save settings in the db. (Its name is theme_mods_MYTHEMENAME in the options table.)

When I delete my theme WordPress did not delete that value in the db.

And @nacin said "This doesn't seem like functionality I'd want themes to have."!
I don't think you love junk.

Please have a function to work on delete/uninstall the theme.

[swissspidy]

@okvee Theme mods are somewhat different. I understand this ticket to be about helping themes to remove their custom tables etc. on uninstall (which themes really shouldn't use). Theme mods are handled by WordPress and crucial to the overall UX. When changing themes and previewing them in the customizer, I want to have the same modifications (e.g. custom CSS) applied as before. I don't want this data to get lost.

[pbiron]

adds delete_theme and deleted_theme actions

[pbiron]

14955.2.diff adds the delete_theme actions before the deletion attempt and the deleted_theme action after the deletion attempt.

I think #37951 should be opened back up as it is more appropriate to these hooks (since this ticket was originally intended for theme uninstall hooks), but since @vetyst was encouraged to add his similar patch to this ticket I did as well.

My use case is simple: I've got a plugin that modifies the database when themes are installed (which it detects by hooking into ​upgrader_process_complete) and I need it to cleanup after itself when themes are deleted.

[bookdude13]

The auto-updates feature plugin also needs this hook to clean up update metadata about themes. Even if themes shouldn't need clean-up hooks, plugins relating to themes do.

The patch applies cleanly, I move for this being added.

[desrosj]

I came across this looking for a theme equivalent to deleted_plugin hook only to find it doesn't exist yet.

14955.2.diff​ looks like it would solve my use case, but it does not address the original ask of the ticket. Since an active theme cannot be deleted, any hooks in the theme will not be registered, so using deleted_theme wouldn't work. I'm reopening #16401 and will use that ticket to commit these hooks.

I do see a difference between using switch_theme and waiting to delete options until the theme is actually deleted. It's not uncommon to switch themes to try a new one out before switching back if you prefer the old one. If a theme used switch_theme to remove custom settings or options, the user would lose their customizations.

That said, the purpose of and concept of what constitutes a theme is undergoing a massive shift with the introduction of full site editing in 5.8 and theme.json files. I don't know that I see a clear use case of an uninstall hook in FSE era themes yet.

With that in mind, and that this ticket has seen no meaningful movement in 5+ years, I'm going to close this out as a maybelater. Discussion can always continue on maybelater tickets, and they can be reopened once things become more clear.