Find efficiently "greater" string in model attribute

rubyonrails-talk
1

How can I find efficiently the model Invoice with the greater code (invoice attribute) when the code is a string like "1/10", "2/10", "3/10" (without quotes) and where only the number before the slash count? 1/10 < 2/10 < 3/10 < 11/10 < 12/10, etc...

2

Now I'm using:

  def after_initialize     if self.new_record? and self.codigo.blank?       max_codigo = FacturaEmitida.all.map{|f| f.codigo.split('/')[0].to_i}.max       if !max_codigo.nil?         self.codigo = (max_codigo + 1).to_s+'/'+Date.today.strftime("%y")       else         self.codigo = "1/"+Date.today.strftime("%y")       end     end   end

but I think it is very inefficient.

3

If the 10 is the year then I would suggest storing the invoice number (1,2,3) separately from the year. Then build the full string (1/10) when you need it. You may not even need the year code if there is a created_at field.

Colin