Is there any way to select an ActiveRecord relation for update?

Question

In Rails 6.1 I would like to select a relation for update (lock the rows inside a transaction).

Foo.transaction do
  # this is foos_query in raw sql
  ActiveRecord::Base.connection.execute <<~SQL
    SELECT FROM "foos"
    WHERE
      type = 'bar' AND
      associated_object = '#{thing_id}' AND
      other_party_id = '#{user_id}'
    ORDER BY id
    FOR UPDATE
  SQL
  foos_query.update_all(read: "true", seen: true)
end

In previous versions of rails, I think this could be hacked with foos_query.lock.pluck(''), but it stopped working at some point.

Is there a supported or hacky way to do this without raw sql?

https://api.rubyonrails.org/classes/ActiveRecord/Locking/Pessimistic.html — mu is too short, Oct 15 '21 at 00:50
@muistooshort i think there's no way to do it on the entire relation without loading the AR objects into memory — John Bachir, Oct 16 '21 at 11:28

score 0 · Answer 1 · answered Oct 16 '21 at 11:29

0

I went with

ActiveRecord::Base.connection.execute foos_query.order(:id).lock.to_sql

Is there any way to select an ActiveRecord relation for update?

1 Answers1