Just another blog…

I was trying to build a nested form with Rails 3.1, using models that had a “has_one” relationship. The form would show the parents fields but not the nested models field.

So I started by defining the has_one relationship in the models and adding “accepts_nested_attributes_for to the Parent :

class Parent < ActiveRecord::Base
  has_one :child, :dependent => :destroy
  accepts_nested_attributes_for :child
 end
 
 class Child < ActiveRecord::Base
  belongs_to :parent
 end

Just this wasn’t enough. The solution involves initializing the Child by the Parent. This can be done in the Controller or the Model.

In the Model:

class Parent < ActiveRecord::Base
has_one :child, :dependent => :destroy
accepts_nested_attributes_for :child
 
after_initialize do
  self.child ||= self.build_child()
end
end

Or in the Controller:

class ParentsController < ApplicationController
def new
  @parent = Parents.new
  @parent.build_child
 end
end

So, a question, where is the best place to initialize the Child? In the Parents Controller or Model?