Question

I have a table with contacts, a table with events, and a joining table with contact_id and event_id to map their many-to-many relationship.

I’m new to RoR and I’m used to querying the first table, building a set of IDs and running a query on the second table where id IN setofids. Is that how its done in RoR as well?

Here’s what I have so far:

def view
 @contact = Contact.find(params[:contact_id])
 @contactevents = Contacts_Event.where(:contact_id => params[:contact_id])

 s1 = Set.new 
@contactevents.each do |contactevent| 
  s1.add(contactevent.event_id)
end

 @contactevents_test = Event.where(:id => @s1)

end

Answer 1

well that is one way to do it but really you are looking at the has_and_belongs_to_many association (guide here). The idea is that when you do @contact = Contact.find(params[:contact_id]) it will automatically pull all of the associated Contacts_Events as well with one query.