Thursday, October 8, 2015
On Wednesday, 7 October 2015 20:47:54 UTC-4, Ruby-Forum.com User wrote:
I have two tables in my app which I am attempting to relate through a
join table. The Artist class which uses 'has_many through', works as
expected. However, the Event class using 'has_one through', brings back
nil.
class Artist < ActiveRecord::Base
has_many :artist_events, dependent: :destroy
has_many :events, through: :artist_events
end
class Event < ActiveRecord::Base
belongs_to :artist_event
has_one :artist, through: :artist_events
Something hasn't been copied correctly here, because this shouldn't work - the `through` refers to an association (artist_events) that doesn't exist on Event.
As noted elsewhere, `belongs_to` is likely not the right association to use here; it's expecting an 'artist_event_id' column on the 'events' table.
You'll also want to carefully consider if `has_one` is the right association as well. The table structure you've set up (Artist / ArtistEvent / Event) is a classic many-to-many relationship. If an Event can truly only have one artist, this structure is not needed. If an Event can have many artists, than a has_one isn't correct.
--Matt Jones
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