Unexpected behaviour for none scope

[bendilley]

where post_id: Post.none

creates a clause like

"post_id" IN (SELECT "posts"."id" FROM "posts")

which is exactly the same as you get with

where post_id: Post.all

This is contrary to what I think most would expect.

I'm not sure how this particular scenario should be addressed. One option might be to generate something like this instead:

"post_id" IN (SELECT "posts"."id" FROM "posts" WHERE 1 = 0)

[kaspth]

I don't think the none relation was meant to be used in queries like this.

Honestly I'm having trouble understanding what you're trying to fetch. Won't where(post_id: nil) work?

[senny]

Probably related to #15763

@kaspth the use case I can see is that you have a method which determines the subquery using a relation. That method could return Post.none in some cases and a different relation in others.

[kaspth]

@senny 👍 that would make sense.

[senny]

@bendilley what version of Rails are you using?

I remember working on that exact issue. See #15176 and c2357eb

[bendilley]

@senny I'm using Rails 4.0.12

You're right - your commit does address this very problem. From which version of Rails is your fix applied?

[bendilley]

Oh I see - it's in 4.2.0. Thanks for your help @senny!

Closing as a dupe of #15176

[senny]

@bendilley I just checked and the patch is only applied on 4-2-stable and master. I'll look into a possible backport to 4-1-stable.

As far as I know the last bugfix release for 4.0. is over so you'd have to upgrade.

[bendilley]

No worries, thanks @senny. I have a serviceable workaround for now - I just wanted to raise it coz it caught me out. Evidently I wasn't alone... I guess I didn't search existing issues thoroughly enough 😅

[senny]

backported the patch to 4-1-stable.

@bendilley thank you for reporting! 💛