Situation: we're creating an application for orders and order tracking. base class : Qoi (quotations, orders, invoices). Quotations < Qoi, Orders < Qoi , Invoices < Qoi
Each Qoi has_many :line_items (each line item has unit price, amount,...) Each line_item --> has_many :rfq_of (Request_for-Quote + Order_Form) for some items we must ask for price to our suppliers so we must create one or more requests for quote and --> has_many :log_items These are used for logging deadlines, phone calls...
When a Quotation becomes an Order we copy the line_items. This way we can keep track when things change during the lifetime of an order (eg the amount changes, so we can still see that in the Quotation we offered 3 MacBooks, but the client ordered only 2.
Now the problems start to bubble up... When copying a line_item we loose the relation to all rfq_of and log_items... We tried to solve this using an extra id in a line_item : base_id. When creating a new line_item we set base_id = id, when copying a line_item, base_id is just copied. This way we can track back to the original line_item and find all rfq_of's and log_items...
We would need a relation from base_id (in line_items) to line_item_base_id (in rfq_of), but afaik rails doesn't support relations that start from a differente field than id....
We could do this in a few ways: 1) in line items we could write : belongs_to :base_record, :class => "LineItem", :foreign_key => :base_id this way we can retrieve the 'base' record and it's rfq's via: @line_item.base_record.rfqs ---> is will give us trouble if for some reason the original line_item in the Quotation is deleted...
2) we could not use relations but do a find RfqOf.find(:all, :conditions {:line_item_base_id => base_id}) I can't give a logical explanation but we don't like this solution, it looks overly complex. And we will need to write a lot of 'search methods for everything
Both solutions also have the problem that we can't use :dependent => :destroy, in the first case rfq_of's would be destroyed if the base line_item was destroyed, in the second case it can't be automated. Rfq_of (and log_items) should be destroyed if all line_items of the same family (same base_id) are destroyed.
Is there better way, either by not using the base_id or a completely different structure... (extra table, wrapper,..)
