Redirects in Discourse from Xenforo

[Fajfi (Dominik)]

On my Xenforo board links look like this:

For category:
https://example.com/forums/category.1234/
/forums/category-name.ID/

For post:
https://example.com/threads/thread-name.1234/
/threads/thread-name.ID/

Unfortunately I guess by the amount of / and . redirection does not work after addning it in the discourse panel (/admin/customize/permalinks), is there any way to repair this and create proper redirection?

[pfaffman (Jay Pfaffman)]

There is a permalink_normalization site setting to help with that.

[Arkshine]

Also:

@neil

Permalink Normalization

@bletch

Just wanted to circle back to this to mention a few of the gotchas that I found and perhaps leave some breadcrumbs for future travellers - because I found this hellishly difficult to debug.

Escaping in the permalink normalization string

The format of the permalink normalization string has two components

1. the Regular Expression string
2. the Replacement string

They appear, one immediately after the other, in the permalink normalization string like so

         Permalink Normalization
    Regular Expression       Replacement
<-------------------------><------------->
/(this)reallyis(intuitive)/\1reallyisn't\2

Importantly, slashes are treated differently in the different parts of the same string.

A slash (and other regex chars) in the Regular Expression part of the string must be escaped, however, slashes do not need to be escaped in the Replacement part of the same string and will instead be treated literally.

The Format of incoming URL strings

Secondly, and this took me a while to nail down, you match the URL as a relative path description from root but you will not receive the / as the first part of the string.

For example, if the URL that your old forum uses looked like this…

http://oldforum.com/chat/the-topic-title/post/d9aa09c3-19bd-4c6e-9d8d-a8f1008000a1

…then the URL that your the regular expression in your permalink normalization will match against will look like this…

chat/topic-title/post/d9aa09c3-19bd-4c6e-9d8d-a8f1008000a1

i.e. a path description from root but without the leading / slash. (I guess that YMMV here depending on the structure of the URLs that you are redirecting - but I don’t think so).

Examples

Here are some examples from my migration project

CATEGORY_LINK_NORMALIZATION = '/(cat)\/(.*?)([#\?].*)?$/cat/\2'
POST_LINK_NORMALIZATION = '/chat\/(.*?)\/(post)\/(.+?)([#\?].*)?$/post/\3'
TOPIC_LINK_NORMALIZATION = '/(chat)\/(.*?)([#\?].*)?$/topic/\2'

The Process

Old URL	Permalink Normalization	URL Match Text
http://oldsite.com/cat/history	/(cat)\/(.*?)([#\?].*)?$/cat/\2	cat/history
http://oldsite.com/chat/topic-title/post/d9aa09c3-19bd-4c6e-9d8d-a8f1008000a1	/chat\/(.*?)\/(post)\/(.+?)([#\?].*)?$/post/\3	post/d9aa09c3-19bd-4c6e-9d8d-a8f1008000a1
http://oldsite.com/chat/mindgames-in-football	/(chat)\/(.*?)([#\?].*)?$/topic/\2	topic/mindgames-in-football

The Old URL is as it sounds - the URL of the item in the old system.

The permalink normalization (recorded in the permalink_normalizations system setting) will grab the incoming URL (without the leading slash /) and apply the regex match. The resulting normalised URL is then used to match against the URL Match Text entered on the /admin/customize/permalinks screen.

Redirect old forum URLs to new Discourse URLs

Redirecting Old Forum URLs to New Discourse URLs If you’ve moved from other forum software to Discourse using one of our import scripts, then you probably want all your hard-earned Google search results to continue pointing to the same content. Discourse has a built-in way to handle this for you as an alternative to writing nginx rules, using the permalinks lookup table. The permalinks table allows you to set two things: a url to match, and what that url should show. There are a few options …

[Fajfi (Dominik)]

Thanks!

Here’s regex for permalink normalizations for my case on XenForo:

https://example.com/threads/thread-name.1234/
/(threads)\/(.*?)([0-9].*)?$/threads/\3

https://example.com/forums/category.1234/
/(forums)\/(.*?)([0-9].*)?$/forums/\3

---

When there’s numbers in thread-name or category use this

/(threads)\/(.*?\.)([0-9].*)?$/threads/\3

/(forums)\/(.*?\.)([0-9].*)?$/forums/\3