This pull request follows on from https://github.com/discourse/discourse/pull/16308. This one does the following:
* Changes `BookmarkQuery` to allow for querying more than just Post and Topic bookmarkables
* Introduces a `Bookmark.register_bookmarkable` method which requires a model, serializer, fields and preload includes for searching. These registered `Bookmarkable` types are then used when validating new bookmarks, and also when determining which serializer to use for the bookmark list. The `Post` and `Topic` bookmarkables are registered by default.
* Adds new specific types for Post and Topic bookmark serializers along with preloading of associations in `UserBookmarkList`
* Changes to the user bookmark list template to allow for more generic bookmarkable types alongside the Post and Topic ones which need to display in a particular way
All of these changes are gated behind the `use_polymorphic_bookmarks` site setting, apart from the .hbs changes where I have updated the original `UserBookmarkSerializer` with some stub methods.
Following this PR will be several plugin PRs (for assign, chat, encrypt) that will register their own bookmarkable types or otherwise alter the bookmark serializers in their own way, also gated behind `use_polymorphic_bookmarks`.
This commit also removes `BookmarkQuery.preloaded_custom_fields` and the functionality surrounding it. It was added in 0cd502a558 but only used by one plugin (discourse-assign) where it has since been removed, and is now used by no plugins. We don't need it anymore.
It's very easy to forget to add `require 'rails_helper'` at the top of every core/plugin spec file, and omissions can cause some very confusing/sporadic errors.
By setting this flag in `.rspec`, we can remove the need for `require 'rails_helper'` entirely.
Instead of going to the OP of the topic for topic-level bookmarks
(which are bookmarks where for_topic is true) when clicking on the
bookmark in the quick access menu or on the user bookmark list,
this commit takes the user to the last unread post in
the topic instead. This should be generally more useful than landing
on the unchanging OP.
To make this work nicely, I needed to add the last_read_post_number to
the BookmarkQuery based on the TopicUser association. It should not add
too much extra weight to the query, because it is limited to the user
that we are fetching bookmarks for.
Also fixed an issue where the bookmark serializer highest_post_number was
not taking into account whether the user was staff, which is when we
should use highest_staff_post_number instead.
