Accessing parent object attribute from child's object in Rails

Question

I have a model called Category which looks like this:

class Category < ActiveRecord::Base
  has_many :categories
  belongs_to :category,:foreign_key =>         


        

Answer 1

I'm not sure I completely understand your question, but category.parent.name should work. If a category doesn't have a parent, do something like category.parent.try(:name) to avoid getting a NoMethodError.

Answer 2

Self referencing associations are hard at the first time...

class Category < ActiveRecord::Base
  has_many :children, :class_name => 'Category', :foreign_key => 'parent_id'
  belongs_to :parent, :class_name => 'Category', :foreign_key => 'parent_id'
end

Then you could call category.childrenand category.parent and also access all the attributes of the asscoiated oobjects,...