Discourse Category Sidebars

This theme component takes a topic and applies it as a sidebar for a category’s topic list. These sidebars are only visible when the browser is 767px or wider (most tablets and monitors).

Want sidebars for tags? Check out Discourse Tag Sidebars.

What can I do with this theme component?

  • Choose a topic and display its content as a sidebar for a category.

  • Set a sidebar to be displayed on the /latest, /new, /unread, and /top pages by using all as the category name in your settings.

  • Choose for the sidebars to appear on the left or the right of the topic list.

  • By default a category’s sidebar will also display for all its subcategories unless a subcategory has its own sidebar defined (you can disable this by unchecking the inherit parent sidebar setting).

How do I configure it?

Simply insert the category slug (from the category url, e.g. example.com/c/staff) and the id of the topic (e.g. example.com/t/example-topic/57)

I recommend creating sidebar topics in their respective categories, closing the topic so there are no replies, and unlisting it (so it doesn’t appear in the topic list).

Note that you can not use a topic in a private category as a sidebar in a public category (you can, but users without access to that private topic will just see a blank sidebar!).

Custom CSS

Each category sidebar is wrapped with a class that contains the category slug, so for the staff category that would be .category-sidebar-staff. You can use these classes to style the individual sidebars.

The body tag on pages with sidebars also has a class added so you can use body.custom-sidebar to apply styles on all pages that have a sidebar.

:heart: Special thanks to @xrav3nz for laying the groundwork to make this component possible!

Install this theme component


Trying to figure out how to make this work with tags as well. (we use tags heavily rather than having tons of categories.)

It looks like it may be about replacing controller:navigation/category with whatever the equivalent for tags is but not sure.


I just took a quick look and it’s possible to do this for tags…

I’ll probably work on this more tomorrow and spin it off into its own repo.

Yep, that’s the core of it — this seems to work for tags:

const controller = container.lookup("controller:tags-show");
const tag = controller.get("tag");

Update: I’ve got a theme component available, Discourse Tag Sidebars


Since I am using the header submenu plugin, A part of the text is covered by my header bar. It would be great if it was possible to add extra margin/offset or whatever it’s called for the case when additional elements before the header are covering the sidebar’s content.

Also: is there any way to keep the category drop down menu above the sticky sidebar’s content? that would make it easy for users to jump between categories quickly.

altogether I think the category sidebar is a great plugin and has huge potential to add useful information to the forum structure!

Another great plug-in Kris, thanks!

I have a few questions/suggestions that I hope you can help with…

1 - Is it possible to make this so that when a user browses the forum, going from page to page the sidebar always checks for the latest version of the post that it contains? At the moment I think the content of the sidebar only updates on a page refresh? Unfortunately content that rarely changes begins to appear stale to users (particularly active users) and so I’d like to update the topic associated with the sidebar frequently if I can. (Similarly, if the ID of the topic in the options for that page is changed, it would pick it up on the next page-view). I’m quite happy for the additional load per page/view but if you’re worried others may not be perhaps you could add a “cache post contents” option which would make it work like it does now.

2 - Is it possible to associate/pick up content from more than one topic per sidebar please? So for example on the Latests page you might want the content from topics 33,55 (and in that order). This would be great to allow different content per page while also include common info/links that you might want to appear at the bottom of every sidebar.

3 - Is it possible to expand the plugin so it can be used site-wide please? At the moment I think it can only be used on certain pages? Ideally I’d like to use this across the whole forum on all main sections/pages. (Perhaps your tags sidebar plugin could be used in conjunction with this for finer control - eg for individual tags and/or Topics - I think both combined could become a very power sidebar package!!)

4 - Is it possible to add a sidebar width option as well as a configurable cut-off/display-none point please? This isn’t a biggie as it can be done via css changes but think it would be nice to have in the options.

5 - Last but not least… could you get polls to work please? I think allowing users to vote in polls right out of the sidebar would be awesome!!! I find dynamic content like this in sidebars can make them interesting to users, and so less likely that they’ll automatically ignore them.

I think with all the above this plugin would make a very good candidate to be included in core or an official DC plugin - imo it could help people put an individual stamp on their forums and I’m sure people would use them in fun and interesting ways! :smiley:


Great component. Is it possible to have such sidebar for each topic under a specific category?


What is the syntax to adress a subcategory? Things I tried so far:


None of these seem to work. Main categories are displayed, though.

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Hm, anyone, please? It shouldn’t be that hard to give an answer…

It looks like there was a regression and subcategories weren’t working in some cases, the syntax should be the same as categories: subcategory, 123

I’ve refactored the theme, so if you update it subcategories should work as expected!


That did the trick: perfect!
Thank you so much, just in time for our grand opening.

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Awesome plugin!

Is this by any chance possible for groups as well? Having a sidebar for groups would be great to give information about the group.

Can anyone direct me in a way to get the group parameters (let the component know you’re inside a group) so I can attempt it and create a PR myself?

@hyphalos I’ve created a Groups Widget that can be added to sidebars of the Layouts Plugin.

Perhaps the code I had for that will help you to write your PR:

Alternatively, you could also use the Layouts plugin and the widget itself.


It might be a bit bold to ask for it, since it’s called sidebar, but: would it be possible to add an option to place the content not beside, but always above the topic list?

We use Discourse as a social intranet, and for some categories we have the need for a well-maintainable area for links, lists of people, etc. - this machanism would be great for that, but there is just too little space in the sidebar.
CSS hacks are also welcome.

I’ve already tried the category banners, but they are limited to the first paragraph so this is not an option.

(Berlin State Library)

What about this TC?

You will still be stuck with the first paragraph I think. But that could potentially be altered.

Hi Kris, This is quite nice.

I was wondering if this could be modified or have an option to move it from a sidebar to Top bar below site header or maybe just below a category logo?

Or if I might get guidance on adding custom css to move it and also have it display for mobile as a top is it sticky bar? anchored just below site main bar?