Rails 3 controller methods for nested resource don't run - ruby-on-rails-3

Question

I'm creating nested resources Foo and Bar where Foo has_many Bars and Bar belongs_to Foo
This is the new method in BarsController:
def new
#foo = Foo.find(params[:foo_id])
#bar = #foo.bars.build
end
This is the code for the Bar new view:
<%= form_for([#foo, #bar]) do |f| %>
<%= f.text_field :name %>
<%= f.submit "Save" %>
<% end %>
When I try to load the "new bar" page, rails says that the model_name method cannot be found for value Nil. Curiously, this slightly modified view code works:
<%= form_for([#foo, #foo.bars.build]) do |f| %>
<%= f.text_field :name %>
<%= f.submit "Save" %>
<% end %>
However, when I put a logger.debug statement inside the new method in BarsController, it never runs. rake routes says and the server log confirms that BarsController#new is the action being called, but why won't the code that's inside the new action run? Am I missing something here?

Answer 1

Some changes you could make to make it work:
Bars is nested in Foo not the opposite, so instead of BarsController you should write your new action inside your FoosController as follow:
def new
#foo = Foo.new
#bar = #foo.bars.build
end
Inside your foo model you should have:
accepts_nested_attributes_for :bars
Your view:
<%= form_for #foo do |f| %>
<%= f.fields_for :bars do |ff| %>
<%= ff.text_field :name %>
<%= f.submit %>
<% end %>
Don't forget the create action inside your FoosController:
FoosController
def create
#foo = Foo.new(params[:foo])
if #foo.save
redirect_to #foo
else
render :new
end
end
Finally, pay attention to the validations written in your models! For instance it is possible that some fields (that you forgot to fill during your tests) are necessary for your form to be valid! Happened to me recently!