Fix permalinks to point to topic-url and not to first post of topic

Migration
1

After a customized migration many permalinks were pointing to the first post in a topic instead of the topic-url itself.

e.g. permalinks pointing to
https://forum.example.com/t/example-topic/123/1

instead of
https://forum.example.com/t/example-topic/123

Check

A Discourse forum is affected if there are records for this SQL query:

SELECT permalinks.*,
       posts.id,
       posts.topic_id,
       posts.post_number
FROM permalinks
         LEFT JOIN posts
                   ON posts.id = permalinks.post_id
WHERE permalinks.post_id IS NOT NULL
  AND posts.post_number = 1
LIMIT 20;

Quick Fix

This changes permalinks to directly point to the topic, if they were originally pointing to the first post in topic.

UPDATE permalinks
SET topic_id = posts.topic_id,
    post_id  = NULL
FROM posts
WHERE permalinks.post_id = posts.id
  AND permalinks.post_id IS NOT NULL
  AND posts.post_number = 1;

This might be a good cleanup routine to run at the end of migration scripts.

1 Like
2

How did you create the permalinks?

For example, here discourse/script/import_scripts/vanilla_mysql.rb at main · discourse/discourse · GitHub they specifically check the post number, if it’s 1, then the post_is not passed (left as NULL) and thus the permalink shouldn’t point to the first post.

2 Likes
3

I did a SQL based approach on permalinks based on some code similar to

… but with AND post_number <> 1 missing – so that was the culprit.

1 Like
4

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