Destroying after save if association is blank? - ruby-on-rails

Question

How would I destroy a Product if it doesn't belong to a Store after_save?
class Product < ActiveRecord::Base
attr_accessible :price, :name, :product_store
belongs_to :store
attr_reader :product_store
# I need this to do also "p.product_store.blank?"
after_save { |p| p.destroy if p.name.blank? && p.price.blank? }
def product_store=(id) # using Jquery TokenInput so only needed this.
self.store_id = id
end
end
I've tried a couple of different approaches like:
after_save { |p| p.destroy if p.name.blank? && p.price.blank? && p.product_store.blank? }
after_save { |p| p.destroy if p.name.blank? && p.price.blank? && p.store.id.blank? }
after_save { |p| p.destroy if p.name.blank? && p.price.blank? && p.store_id.blank? }
after_save { |p| p.destroy if p.name.blank? && p.price.blank? && p.store.blank? }
But these didn't work so I ask for your help on how it would be done?
Here is my form and controller: https://gist.github.com/1472629

Answer 1

how about use ActiveModel::Validations?
you don't want to save record if some attribute not filled.so you need validation.
class Product < ActiveRecord::Base
validates_presence_of :name, :price, :store_id
end
Edit:
your code looks want to create muti products use common attributes.
may be params like this:
{"products" => {:1 => {:name => "good", :desc => "sss"}}, {:2 => {:name => "good", :desc => "tt"}}, "product" => {:price => "10"} }
controller
def create_multiple
#products = params[:products].values.collect do |up|
Product.new(up.merge(params[:product]))
end
if #products.each(&:save)
redirect_to :back, :notice => "Success!"
else
render :new
end
end
Validation do not need change. but the form will a bit complicate.
form_tag "/products" do
%p
= text_field_tag "product[price]", #products.first.price
= #products.first.errors[:price]
- #products.each_with_index do |product, idx|
= text_field_tag "products[#{idx}][name]", product.name
= product.errors[:name]
= submit_tag :submit
the code is simple, you can enhance the view yourself.

Answer 2

This seems more like a validation issue. If it's invalid without a Store, then you shouldn't save it to the DB without a Store reference at all.
If you want to destroy the Product you should do that directly, rather than saving a nil reference to a store, trying to catch that, and then destroying it as a result.
By trying to destroy a record when its association is incorrect, you're essentially saying, "This in an invalid state, and shouldn't be in the database in the first place."