Rails: Virtual Association?

I have an Invoice model that has an status_id attribute, this model belongs t开发者_StackOverflow社区o Status models.

The Invoice.status_id can be "0 => active" or "2 => closed" in the DB.

The thing is in my Status model i also have ":id => 1, :name => due", but this is only when the Invoice.payment_date is less than today.

So my question is how can i something like

i = Invoice.find(:first)
i.status.name # i need this to return due if the Invoice.status_id == 0 and
              # Invoice.payment_date < Date.today

Obviously the above code is always returning the name based on the value Invoice.status_id, because the association is correct.

I hope it make sense and somebody can help me.

Thanks.

Is there a reason Status has to be a model? If not, I would make it a method like this:

class Invoice < ActiveRecord::Base
  def status
    if closed?
      "closed"
    elsif payment_date < Date.today
      "due"
    else
      "active"
    end
  end
end

Then add a boolean field closed to the invoices table.

I was looking the problem the wrong way. Once i read a little more of ActiveRecord and searchlogic, it came to me: named scope!!!