How to pass data to IN query in rails 3

You can just pass an array in. Rails is clever enough to to the right thing with it:

items = [  @invitation_user1.id,  @invitation_user2.id,  @user1.id,  @user2.id,  @profile1.id,  @profile2.id]@activities = Version.where("item_id IN (?)", items)# or equivalently:@activities = Version.where(:item_id => items)

This is vastly preferred over your variant, as Rails properly handles escaping of all passed values for the used database adapter.

Use array instead of string.

For example

ids = [ @invitation_user1.id, @invitation_user2.id, @user1.id, @user2.id ]

Then easily you can find the records by

@versions = Version.find_all_by_id(ids)

This will result the query you expected.

SELECT "versions".* FROM "versions" WHERE (item_id IN (19,20,4,1))

What you are looking for is split:

[1] pry(main)> a = '19,20,4,1,1,4,1'=> "19,20,4,1,1,4,1"[2] pry(main)> a.split(',')=> ["19", "20", "4", "1", "1", "4", "1"][3] pry(main)> a.split(',').map(&:to_i)=> [19, 20, 4, 1, 1, 4, 1]

But, as you are constructing the 'string' manually, better to use an array:

items = Array.newitems << @invitation_user1.id << @invitation_user2.id << @user1.iditems << @user2.id << @user2.id << @profile1.id << @profile2.id@activities = Version.where(item_id: items) 

Anyway, the way to get the ids is strange because... what would happen if you added more users? or profiles?

What I would do (seeing as little as we can see in your example)

items = Array.newitems << get_invitation_user_idsitems << get_user_ids items << get_profile_ids@activities = Version.where(item_id: items)

and later define those methods, as in:

def get_invitation_user_ids  InvitationUser.select(:id).map(&:id)end...