union operation in find method, similar to the IN Operator in SQL

[joker-777]

Hi

I always wanted s.th. similar like the SQL Operatorfor 'IN' for ohm.

I've implemented it now for Model.find and I was wondering if you have any thoughts about it?

In our case we have 4 slugs and instead of doing this:

[slug1, slug2, slug3, slug4].each do
  object = Model.find(slug: slug, user_id: some_id)
  ...
end

We wanna do

Model.find(slug: [slug1, slug2, slug3, slug4], user_id: some_id).each do |object|
  ...
end

Could there be some performance issues? What would be more performant?
I didn't run any test yet nor didn't write any. I first would like to get some other views about this subject.

Thanks

[cyx]

Hello,

Due to my nature to want to be able to control these sort of stuff (and most of the time use cases like these
appear in some kind of performant-requiring context), I tend to hand code these.

Here's an example of a simple enough implementation: https://gist.github.com/d05e53cc3f1ae7623a8e

[gingerlime]

@cyx - thanks for the snippet. It is quite simple as you said, but still requires much more familiarity with the inner mechanisms of both ohm and redis.

I'm working with @joker-777 so perhaps I'm biased, but I think that from an ohm end-user's perspective (in my case, a rather inexperienced one), using find with an array makes it much more similar to other ORMs and much more intuitive. If this doesn't break anything, I think it could be a very elegant and useful addition to ohm.

[joker-777]

Hi @cyx

Thanks for your answer. I think similar to @gingerlime.
Just finished it up, fixed some tests and added some more. I also changed the documentation a bit. My implementation only breaks this tag usescase where you have an array as an attribute and you can filter by single elements of this array.
This has to be put now in another array...like this:

User.find(:tag => [["ruby", "python"]])

I hope you will merge this pull request nevertheless.

[gingerlime]

any chance of getting this merged? or a reason why it definitely shouldn't?

[gokulj]

+1 for including this.

[frodsan]

I think you can do User.find(slug: [slug1, slug2]).union(user_id: some_id).