When a category is removed, uncategorize feeds/categories explicitly to plugins

[39aldo39]

Currently, when a category is removed without children, its feeds/categories are uncategorized. However, these changes aren't sent to the plugins. For example, in Nextcloud the children are removed.

This pull request sends these changes explicitly to the plugin.

[brendanlong]

I'm not sure if this will work right if plugins support multiple categories per feed, although I'm guessing the original logic isn't right either. Do you know how to review this @jangernert ?

[brendanlong]

Is it possible that this belongs at the plugin level, in OwnCloudNewsInterface.deleteCategory (under plugins/backend/owncloud), and the NextCloud plugin is just implementing that function incorrectly?

[jangernert]

Thx for your efforts with this PR :)

I would also suggest to move this into the NextCloud plugin. Most RSS services have children of deleted categories still around as uncategorized.

[39aldo39]

I do think the implementation is correct when a feed has multiple categories. The function moveFeed only removes the given category from the feed.

Also, it is quite tricky to implement it in the plugin, since the database might update before the plugin method is called, in which case the children cannot be read from the database.

I mainly made the change for my fork with a plugin for syncing with my DecSync. For that plugin, it is way easier to implement the deleteCategory with this pull request. I thought of doing a pull request for that plugin next week. It also needed another change, a bit similar to this one.

[brendanlong]

Ok I looked at this a little more, and I'm still a little worried because this part of the code is pretty flaky, but I'm pretty sure this pull request won't make it any worse. Hopefully sometime soon we'll be able to test the plugins.

This seems to work in Feedbin (well.. as well as it worked previously, which is "barely"). Do you mind if I merge this @jangernert?

@39aldo39 I took a look at your fork and I'm happy to review a pull request to add your plugin. I'll try to review it later this week if I can find time, but the major thing that stands out is that we should try not to duplicate the dependencies shared with the local plugin (date parsing, libmrss, etc.).