Rails belongs_to multiple models with accept_nested_attributes_for - ruby-on-rails

Question

I'm building an invoice system for a car trader where each invoice is linked to one customer and one vehicle, with customers potentially having many invoices and vehicles also having many invoices. I have got it working with one nested model doing the following:
purchase_invoice.rb
class PurchaseInvoice < ApplicationRecord
belongs_to :vehicle
accepts_nested_attributes_for :vehicle
end
vehicle.rb
class Vehicle < ApplicationRecord
has_many :purchase_invoices
end
purchase_invoices_controller.rb
def new
#vehicle = Vehicle.new
#purchase_invoice = #vehicle.purchase_invoices.build
end
def create
#vehicle = Vehicle.new
#purchase_invoice = #vehicle.purchase_invoices.build(invoice_params)
if #purchase_invoice.save
redirect_to #purchase_invoice
else
render 'new'
end
end
private
def invoice_params
params.require(:purchase_invoice).permit(:buyer, :location, :vehicle_price, :transfer_fee, :balance_due, :payment_cash, :payment_bank_transfer, :payment_comment, :status, vehicle_attributes: [:vrm, :date_first_registered, :make, :model, :colour, :transmission, :vin, :fuel, :power])
end
new.html.erb
<%= form_with model: #purchase_invoice, local: true do |form| %>
<%= form.fields_for #vehicle do |vehicle_form| %>
<% end %>
<% end %>
However when I add a second relationship like this:
purchase_invoice.rb
class PurchaseInvoice < ApplicationRecord
belongs_to :customer
belongs_to :vehicle
accepts_nested_attributes_for :customer
accepts_nested_attributes_for :vehicle
end
I get an error saying :'Unpermitted parameters: :vehicle'
Does anybody know why? Also, how would I modify the controller new/create action for build whilst maintaining strong params?
I've been Googling this for four hours now and tried a lot but had no luck. Thanks in advance to everybody!
Update
Here's my logs:
Started POST "/purchase_invoices" for 127.0.0.1 at 2018-03-20 15:10:01 +0000
Processing by PurchaseInvoicesController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"JB8py9zNxew6aQ6/za3JHDEb4j8f9HGujTlS6P1Eyhb+5NtPPP47fW7AHBkt9eURcnXg0gh9Mf1DCKCSwvlAbg==", "purchase_invoice"=>{"customer"=>{"name"=>""}, "vehicle"=>{"vrm"=>"SA07SSX", "make"=>"VAUXHALL", "model"=>"MERIVA DESIGN", "colour"=>"Silver", "vin"=>"W0L0XCE7574216645", "date_first_registered"=>"20/03/2007"}, "vehicle_odomoter_reading"=>"", "vehicle_number_of_keys"=>"", "vehicle_mot_expiry"=>"", "vehicle_hpi_clear"=>"", "vehicle_comments"=>"", "buyer"=>"", "location"=>"", "vehicle_price"=>"", "transfer_fee"=>"0", "balance_due"=>"", "payment_cash"=>"", "payment_bank_transfer"=>"", "payment_comments"=>""}, "commit"=>"Create Purchase invoice"}
Vehicle Load (0.3ms) SELECT "vehicles".* FROM "vehicles" WHERE "vehicles"."vrm" = ? ORDER BY "vehicles"."id" ASC LIMIT ? [["vrm", "SA07SSX"], ["LIMIT", 1]]
Unpermitted parameters: :customer, :vehicle, :payment_comments
(0.1ms) begin transaction
(0.1ms) rollback transaction
Rendering purchase_invoices/new.html.erb within layouts/application
Rendered purchase_invoices/new.html.erb within layouts/application (10.2ms)
Rendered layouts/_header.html.erb (1.7ms)
Completed 200 OK in 63ms (Views: 54.4ms | ActiveRecord: 0.4ms)

Answer 1

You approach has some issues but you are very close. The PurchaseInvoice model belongs to a Vehicle and a Customer, and it stores a customer_id and a vehicle_id. That's correct. As you said in the comment, it is much more than just a join model, because it holds many other data, such as price, transfer fees, etc. Anyway, you are passing a lot of params regarding the vehicle to be purchased, and not the id of the vehicle. In fact, you are creating the vehicle in the PurchaseInvoice create, which makes no sense. Moreover, your vehicle_attributes should not be an array, but a hash (because PurchaseInvoice belongs_to :vehicle; so it is just one), and should only have the vehicle_id. And giving that you just need the vehicle_id, you do not need nested_attributes (neither for customer) . I would change:
The controller:
def new
#vehicles = Vehicle.all #All vehicles, to select from the list
#customers = Customer.all #All customers, to select from the list (unless you use current_user)
#purchase_invoice = PurchaseInvoice.new
end
def create
#vehicle = Vehicle.find(params[:vehicle_id])
#customer = Customer.find(params[:customer_id]) # Or use current_user
#The above is only needed to check if vehicle and customer exist, but it is not needed below
#purchase_invoice = PurchaseInvoice.create(invoice_params)
if #purchase_invoice.save
redirect_to #purchase_invoice
else
render 'new'
end
end
def invoice_params
params.require(:purchase_invoice).permit(:customer_id, vehicle_id, :location, :vehicle_price, :transfer_fee, :balance_due, :payment_cash, :payment_bank_transfer, :payment_comment, :status)
end
The view:
<%= form_with model: #purchase_invoice, local: true do |form| %>
<!-- This is necessary to choose the customer. If the customer is current_user, just remove it. -->
<%= form.collection_select(:customer_id, #customers, :id, :name %>
<!-- This is necessary to choose the vehicle. This is extremely simplified -->
<!-- The customer should be able to look at many attributes of the car -->
<!-- to be able to select one to purchase -->
<%= form.collection_select(:vehicle_id, #vehicles, :id, :make %>
<!-- All other invoice fields. -->
<% end %>