activerecord - rails 4 scope through multiple has_one associations -

i trying activerecord association through 2 layers of has_one associations , cannot quite figure out.

i have 3 models:

class dialog < activerecord::base   belongs_to :contact end  class contact < activerecord::base   has_many :dialogs   belongs_to :location end  class location < activerecord::base   has_many :contacts end 

i create scope in dialog model allows me pass in id of location , dialogs created contacts given location... like:

dialog.from_location(location.first.id) 

i can non-activerecord array of desired result using select:

dialog.all.select{|s| s.contact.location_id == location.first.id } 

but need return activerecord array other scopes or class methods can called on result. have tried using joins , includes, confused after reading rails guides on how use them.

can me figure out how construct scope or class method accomplish this?

thanks in advance

you can define scopes follows:

class dialog < activerecord::base   belongs_to :contact    scope :from_location, -> (id)      where(contact_id: contact.from_location(id).select(:id))   end end  class contact < activerecord::base   has_many :dialogs   belongs_to :location    scope :from_location, ->(id)     where(location_id: id)   end end