Question

this is a real hair-puller. I’ve got a junction table that I need to query for 2 different entries, then update the junction table if the values are not there already.

Essentially I have this:

master_actors = [#<Actor2role actorId: 13176, dogTag: 45917, roleId: 1, position: 3>, #<Actor2role actorId: 65471, dogTag: 45917, roleId: 291075, position: 1>]

slave_actors = [#<Actor2role actorId: 11123, dogTag: 5384, roleId: 44, position: 5>, #<Actor2role actorId: 65471, dogTag: 5384, roleId: 291075, position: 0>, #<Actor2role actorId: 66652, dogTag: 5384, roleId: 291073, position: 2>]

I need to compare the contents of each one of those records and if there are entries in slave_actors not present in master_actors I need insert them.

What I can’t figure out is how to compare the contents of those 2 activeRecord relationship objects. Regular array methods like .include? don’t seem to work. Nor does master_actors.attributes == slave_actors.attributes because I get an error saying that the attributes method does not exist for an activeRecord relationship.

Basically I’m really stumped.

Any help would be appreciated.

Answer 1

Have you tried checking if the intersection (ary1 & ary2) is empty ?

EDIT : As mentioned in the comments below, since there is elements in master_actors that can be absent from slave_actors, the difference (ary1 - ary2) was the right answer