ActiveRecord - Find rows with array and update column with array of values?

Question

Lets say I have some Users and I want to update their ages because I put them in wrong at first. I could do them one at a time as:

User.find(20).update(age: 25)

But can I pull the users with an array, and then update each individual with the corresponding place in another array? I'm imagining something like:

User.find([20,46,78]).update_all(age: [25, 50, 43])

I have a list of User ids and what their correct ages are supposed to be, so I want to change the existing ones for those users. What's the best way to do this?

MikeWu · Accepted Answer · 2018-10-03 15:32:41Z

1

One way of doing this, if your backing storage is MySql/Maria you can do something like this:

arr = { 1 => 22, 2 => 55}.map { |id, age| "(#{id}, #{age})" }
User.connection.execute("INSERT into users (id, age) VALUES #{arr.join(',')} ON DUPLICATE KEY UPDATE age = VALUES(age)")

This is assuming your table name is users. Be careful. Since SQL is manually composed, watch out for injection problems. Depends on what you need, this solution might or might not work for you. It for the most part bypasses the ActiveRecord, so you will not get any validation or callbacks.

edited Oct 3, 2018 at 15:32

answered Oct 3, 2018 at 8:51

MikeWu

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