Question

I want to access a legacy database schema from Rails. I have one table NAGIOS_OBJECTS with a primary key OBJECT_ID and one table NAGIOS_HOST_CHECKS that refers to NAGIOS_OBJECTS with a column HOST_OBJECT_ID. I thus defined the relations as follows:

class NagiosObject < ActiveRecord::Base
  has_one :nagios_host_check, :foreign_key => :host_object_id, :primary_key => :object_id
end

class NagiosHostCheck < ActiveRecord::Base
  belongs_to :nagios_object, :foreign_key => :host_object_id, :primary_key => :object_id
end

However, when calling a_nagios_object.nagios_host_check or a_nagios_host_check.nagios_object, I always get nil.

Any idea what is wrong with my code?

Answer 1

foreign_key and primary_key should be strings, not symbols

ex:

class NagiosObject < ActiveRecord::Base
  has_one :nagios_host_check, :foreign_key => 'host_object_id', :primary_key => 'object_id'
end

http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#M001317