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rubyactiverecord

Ruby Activerecord IN clause

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.

Solution

  • From §3.3.3 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:

    Customer.where(orders_count: [1,3,5])

    This code will generate SQL like this:

    SELECT * FROM customers WHERE
(customers.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.