The release notes for 2.4.0.beta9 make various references to sub-sub-categories.

Are these actually enabled in this release, or are they coming soon?

On a related point is there a roadmap for future releases available anywhere?


They are currently behind a hidden site setting, max_category_nesting. Should you wish to test them out, modify the site setting via the console to 3 instead of 2.

Sure, see the #releases category for a high-level overview of planned features.


Great, thanks - I was searching for roadmap because I assumed that releases were what had already been released… :doh: (wot, no Homer emoticon! )


Is there any reasonable chance this setting will be going away? In other words, how “safe” is it to use for production use as a data structure, even if the UX changes significantly?


There is not, no. The setting is here to stay. We’ve chosen to make it hidden as we want to encourage sites to strongly think about their IA (dfn) and if they can make it work with just 1-level of subcategories. Also, the UX of this change is still in flux, as we iron everything out.


Yeah agree, that makes very good sense. We are only considering it for internal administrative type stuff that already has a lot of hierarchy, and those categories would be hidden from non-staff.


Quick guide to set it from 2 (default) to 3 via the console:

cd /var/discourse/
./launcher enter app
rails c

read current value:

[1] pry(main)> SiteSetting.max_category_nesting
=> 2

write new value:

[2] pry(main)> SiteSetting.max_category_nesting = 3
=> 3

6 posts were split to a new topic: Cannot move sub-sub-category from UI

Hello jomaxro, whatever can you teach me up level category to 4 or up to 5?

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There is no support for category nesting greater than 3.


This seems like an awkward implementation for users. After setting up sub categories and then later wanting to move them, I ran across this level restriction. I had to adjust my implementation as a result.

And now I see that it’s possible to have more levels … but (a) the feature is hidden and undocumented and (b) it’s still limited to 3.

I appreciate the update and work, but just don’t understand the restrictions and how they’re supposed to make sense to implementers.

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We haven’t designed the UI or tested performance beyond 3 category levels, so we don’t support it. Supporting 3 is meant to cover some exceptions and wasn’t intended to be the norm, which is why it’s not easily discoverable.


I meet this error:
I can create a topic in sub sub category (A) when in category A, but in homepage when create a topic, in UI to select category don’t display all of sub-sub category (include A)

I see my error same this topic

My Discourse upgrade newest version

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So i found a pretty terrible bug with sub-sub categories.
After i created a category, and then created sub categories, i went into the category, and it let me set a subcategory of it self as its parent.