How do I initialize attributes when I instantiate objects in Rails?
- by nfm
Clients have many Invoices. Invoices have a number attribute that I want to initialize by incrementing the client's previous invoice number.
For example:
@client = Client.find(1)
@client.last_invoice_number
> 14
@invoice = @client.invoices.build
@invoice.number
> 15
I want to get this functionality into my Invoice model, but I'm not sure how to. Here's what I'm imagining the code to be like:
class Invoice < ActiveRecord::Base
...
def initialize(attributes = {})
client = Client.find(attributes[:client_id])
attributes[:number] = client.last_invoice_number + 1
client.update_attributes(:last_invoice_number => client.last_invoice_number + 1)
end
end
However, attributes[:client_id] isn't set when I call @client.invoices.build.
How and when is the invoice's client_id initialized, and when can I use it to initialize the invoice's number? Can I get this logic into the model, or will I have to put it in the controller?
