Rails, ActiveRecord, query id in array of ints, keep order of passed array

Question

I am thinking about the best solution for a problem. Let\'s say that we have a list of ids of ActiveRecord model:

ids = [1, 100, 5, 30, 4, 2, 88, 44]


        

Answer 1

Another possibility for Postgres (9.4 or later):

ordered_ids = [1, 100, 5, 30, 4, 2, 88, 44]
User.joins("join unnest('{#{ordered_ids.join(',')}}'::int[]) WITH " \
           "ORDINALITY t(id, ord) USING (id)").reorder('t.ord')

Notice that the reorder is extremely important.

Solution based on https://stackoverflow.com/a/35456954

Answer 2

regard less of MySQL and Postgresql, if you have a small size of ids,

User.where(id: ids).sort_by { |u| ids.index(u.id) }

Answer 3

With reference to here, for postgresql,

User.where(id: ids).order("position(id::text in '#{ids.join(',')}')")

Answer 4

if you want to get a result of Model::ActiveRecord_Relation

order(Arel.sql("field(id, ids.join(', ') asc"))

Arel.sql is required to prevent the message in log:

Dangerous query method (method whose arguments are used as raw SQL) called with non-attribute argument(s)

Answer 5

users_by_id = User.find(ids).index_by(&:id) # Gives you a hash indexed by ID
ids.collect {|id| users_by_id[id] }

Answer 6

If you are using Postgres you can use intarray

class User < ActiveRecord::Base
  def self.find_in_order(ids)
    self.where(id: ids).order("idx(array[#{ids.join(',')}], id)")
  end
end

you should init module first

CREATE EXTENSION intarray