Ruby Activerecord IN clause

ruby activerecord
Black Dynamite picture Black Dynamite · Apr 16, 2012 · Viewed 47.2k times · Source

I was wondering if anyone knew how to do an "IN" clause in activerecord. Unfortunately, the "IN" clause is pretty much un-googleable so I have to post here. Basically I want to answer a question like this "Give me all the college students that are in these dormitories where the dormitory id is in this array [id array]". I know how to write the query given a single dormitory id, but I don't know how to do it given an array of ids.

Any help is greatly appreciated. I'm sure this is a repost of a question somewhere, so I'll delete this once an answer/better search term is found.

Answer

Chen Kinnrot picture Chen Kinnrot · Apr 16, 2012

From §2.3.3 Subset Conditions of the Rails Guides:

If you want to find records using the IN expression you can pass an array to the conditions hash:

Client.where(:orders_count => [1,3,5])

This code will generate SQL like this:

SELECT * FROM clients WHERE (clients.orders_count IN (1,3,5))

You can also use the arel syntax:

Client.where(Client.arel_table[:order_count].in([1,3,5]))

Will generate the same SQL

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