Rails 3 - multiple level nesting - getting Uninitialized Constant Error - ruby-on-rails

Question

I'm new to both programming and Ruby on Rails. I'm just trying with a sample 2 level deep nesting. When I followed Ryan's Scraps (http://ryandaigle.com/articles/2009/2/1/what-s-new-in-edge-rails-nested-attributes) for 1 level deep nesting everything well and good but when I extended for 2 level deep I'm getting
NameError in ParentsController#new
uninitialized constant Child::Grandchild
My models are like this
class Parent < ActiveRecord::Base
has_many :children
accepts_nested_attributes_for :children, :allow_destroy => true
end
class Child < ActiveRecord::Base
belongs_to :parent
has_many :grandchildren
accepts_nested_attributes_for :grandchildren
end
class GrandChild < ActiveRecord::Base
belongs_to :child
end
And my controller : new method for parent is ->
def new
#parent = Parent.new
2.times do
child = #parent.children.build
2.times {child.grandchildren.build}
end
respond_to do |format|
format.html # new.html.erb
format.xml { render :xml => #parent }
end
end
Don't know what's the error , when I modified the models into
class Parent < ActiveRecord::Base
has_many :children, :through => :grandchildren
has_many :grandchildren
accepts_nested_attributes_for :children, :allow_destroy => true
accepts_nested_attributes_for :grandchildren, :allow_destroy => true
end
class Child < ActiveRecord::Base
belongs_to :parent
has_many :grandchildren
accepts_nested_attributes_for :grandchildren
end
class GrandChild < ActiveRecord::Base
belongs_to :parent
belongs_to :child
end
then I'll get following error-- uninitialized constant Parent::Grandchild..
I Don't know its a silly mistake or what...
Thanks
I have edited my question which is my real requirement. Instead of creating parent, children and grandchildren at a time as mentioned earlier I want to create parent first then child and grandchild together. I have edited the above code as mentioned below,
My model:
class Parent < ActiveRecord::Base
has_many :children
has_many :grand_children
accepts_nested_attributes_for :children, :allow_destroy => true
accepts_nested_attributes_for :grand_children, :allow_destroy => true
end
class Child < ActiveRecord::Base
belongs_to :parent
has_many :grand_children
accepts_nested_attributes_for :grand_children
end
class GrandChild < ActiveRecord::Base
belongs_to :parent
belongs_to :child
end
My children controller -new method:
def new
#parent = Parent.find(params[:parent_id])
child = Child.new
child.grand_children.build
respond_to do |format|
format.html # new.html.erb
format.xml { render :xml => #child }
end
end
My children _form template is
<%= form_for([#parent, #parent.children.build]) do |form| %>
<div>
<%= form.label :name %><br />
<%= form.text_field :name %>
</div>
<div class="field">
<%= form.label :sex %><br />
<%= form.text_field :sex %>
</div>
<div>
<%= form.fields_for :grand_children do |grand_child_form| %>
<%= render :partial => "grand_children/form", :locals => { :form => grand_child_form} %>
<% end %>
</div>
<% end %>
Here I'm not getting any error as such but when I select new child the grand_child is not appearing,
<%= form.fields_for :grand_children do |grand_child_form| %>
<%= render :partial => "grand_children/form", :locals => { :form => grand_child_form} %>
<% end %>
is not getting reflected at all .
Thanks in advance

Answer 1

I believe your error is your association name, but I don't have a rails terminal to try it on.
has_many :grandchildren
should be
has_many :grand_children
GrandChild is camel cased, and would be grand_child underscored, and grand_children when tableized.
I believe rails is using the underscore/tableize methods when doing it's associations, if you're ever having this problem again with an association, take your class name in a console and do
"GrandChild".tableize
"GrandChild".underscore
That will give you your association names.