operation on data for model

rubyonrails-talk
1

you can handle this all in the model

since i don't know your attribute names, i'll just use simple ones, foo, bar and the unique id attribute will be unique_ident

class Model < AR::Base

  before_create :generate_unique_ident

  def generate_unique_ident     unique_ident = foo + bar + self.generate_some_number   end

  private   def self.generate_some_number     ...   end

  validates_presence_of :foo   validates_presence_of :bar end

then just save your model as usual

2

sorry, you've confused me.

foo and bar where my mock columns on your model. i don't understand where this bar table is coming from.

perhaps you need to provide more info on your situtation.

3

well, what you could do in this case is just make it a 'psuedo attribute' and you don't even have to store it in the database

class Product

  def unique_ident     category.category_code + product_code   end end

so in this example say you have

products id: 1 product_code: 333 category_id: 2

categories id: 2 category: cars category_code: ca

p = Product.find(1) p.unique_ident # => "ca333"