Rails isn't using my `foreign_key` in a belongs_to association

Question

I have two models, AssetEvent and Subsystem , and a join model between them AssetEventSubsystem . They look like this:

RehabEvent < AssetEvent
  has_many :asset_event_subsystems
  has_many :subsystems, :through => :asset_event_subsystems

AssetEventSubsystem
  belongs_to  :rehab_event, :class_name => 'AssetEvent', :foreign_key => "asset_event_id"
  belongs_to  :subsystem

Subsystem
  belongs_to :asset_type

When I try to run RehabEvent.new.asset_event_subsystems.build , I get back a ActiveRecord::UnknownAttributeError: unknown attribute: rehab_event_id , which is confusing, because I thought that should have been taken care of by the foreign_key option in the join model.

How do I make rails use the column in my database ( asset_event_id ) instead of the default?

Answer 1

Looks like u need that: ?

RehabEvent < AssetEvent
  has_many :asset_event_subsystems
  has_many :subsystems, :through => :asset_event_subsystems, 
           :foreign_key => "asset_event_id"

AssetEventSubsystem
  belongs_to  :rehab_event, :class_name => 'AssetEvent', :foreign_key => "asset_event_id"
  belongs_to  :subsystem

Subsystem
  has_many :asset_event_subsystems
  has_many :rehab_events, :through => :asset_event_subsystems
  belongs_to :asset_type

And btw, i dont know your project, but can you use just has_and_belongs_to_many ?

Answer 2

您需要在您的has_many关联中以及您的belongs_to定义foreign_key ：

has_many :asset_event_subsystems, foreign_key: 'asset_event_id'