accepts_nested_attributes_for和二阶关联，嵌套形式

Question

I have following models with associations:

class Order < ActiveRecord::Base
  has_many :guests
  has_many :customers, :through => :guests
  accepts_nested_attributes_for :customers
end

class Customer < ActiveRecord::Base
   has_many :guests
   has_many :orders, :through => :guests
   has_many :slips
   accepts_nested_attributes_for :slips
end

class Slip < ActiveRecord::Base
   belongs_to :order
   belongs_to :customer
end

class Guest < ActiveRecord::Base
  belongs_to :order
  belongs_to :customer
end

My nested form looks like this:

<!-- general form -->
<%= form_for(@order) do |f| %>
    <% f.fields_for :customers do |builder| %>
        <%= render "customer_fields", :f => builder %>
    <% end %>
    <%= f.submit %>
<% end %>

<!-- partial customer_fields -->
<p>
    <%= f.label :name%><%= f.text_field :name %>
    <% f.fields_for :slips do |builder| %>
        <%= render "slip_fields", :f => builder %>
    <% end %>
</p>

<!-- partial slip_fields -->
<p><%= f.label :quantity%><%= f.text_field :quantity %></p>

With this setup saving an order works as expected, but I need the order_id to be saved with the slip, so I have a reference between order <-> slip. With this setup I loose the reference. I can get all associated customers, but I'll get all associated slips of the customer related to the order or not.

---

Here the fields of my models: Order -> id
Customer -> id
Guest -> id, order_id, customer_id
Slip -> id, order_id, customer_id

---

The result of an order should look like this

• Order
  
  1. Customer A
     • Slip 1
     • Slip 2
  2. Customer B
     • Slip 1
     • Slip 2
  3. Customer A
     • Slip 1
     • Slip 2
     • Slip 3

---

I've no idea how to accomplish this.

Answer 1

As far as you can't return order_id for order that isn't exist you can do this hook (I haven't test it, so you'll maybe need to fix it)

def create
  customers = params[:order].delete :customers_attributes
  @order = Order.new params[:order]
  if @order.save
    customers.each{|c| c[:slips_attributes].each{|s| s[:order_id] = @order.id} }
    @order.customers_attributes = customers
    @order.save
  end
end

def update
  @order = Order.find params[:id]
  params[:order][:customers_attributes].each{|c| c[:slips_attributes].each{|s| s[:order_id] = @order.id} }
  @order = Order.update_attributes params[:order]
  @order.save
end

Also you'd better to remove all this logic into your model and you can dry it a little. This only about understanding an approach.

UPD for your ID collisions. It is only a scetch again

def create
  customers = params[:order].delete :customers_attributes
  @order = Order.new params[:order]
  @order.customer_ids = customers.inject([]){|a,h| a << h[:b] if h[:b]; a}
  if @order.save
    customers.each{|c| c[:slips_attributes].each{|s| s[:order_id] = @order.id} }
    @order.customers_attributes = customers
    @order.save
  end
end

def update
  @order = Order.find params[:id]
  @order.customer_ids = params[:order][:customers_attributes].inject([]){|a,h| a << h[:b] if h[:b]; a}
  params[:order][:customers_attributes].each{|c| c[:slips_attributes].each{|s| s[:order_id] = @order.id} }
  @order = Order.update_attributes params[:order]
  @order.save
end