Fix duplicate videos in feed group "All"

Open Stypox opened this issue 3 years ago • 1 comments

What is it?

[x] Bugfix (user facing)
[ ] Feature (user facing)
[ ] Codebase improvement (dev facing)
[ ] Meta improvement to the project (dev facing)

Description of the changes in your PR

In #8621 I deduplicated the queries to get feed info, but I made a mistake regarding the "All" group. The LEFT JOIN of the subscription table with the feed groups table rightfully generates multiple results for each subscription (since it is a join), but, for user-created groups, all results except for at most one are, in the end, filtered out by the first condition in the WHERE, because a subscription can appear in a group at most once. When the query was used for the "All" group, though, the first condition in the WHERE would not do anything (the reasoning behind this was to allow subscriptions independently of groups), causing duplicate subscription results to be generated (i.e. one per group the subscription belonged to). This PR fixes the problem by just making the condition on the LEFT JOIN stricter: since when we are selecting all subscriptions we don't need data about groups, the LEFT JOIN now always fails since the condition in the ON would evaluate to false when groupId=all. Therefore, since we are using a left join, it is ok for the groups table columns to not exist, and hence exactly one result gets generated.

Fixes the following issue(s)

Fixes #9024

APK testing

The APK can be found by going to the "Checks" tab below the title. On the left pane, click on "CI", scroll down to "artifacts" and click "app" to download the zip file which contains the debug APK of this PR.