Ruby On Rails - validate nested params in controller (must not be nil)

Question

These are my params:

{"utf8"=>"✓", "authenticity_token"=>"0RYiIDDgmOk0gCDRkAgHvv+UIgp/BuU33CLThJXqOTE=", 
    "order"=>
            {"operation_in_orders_attributes"=>
                 {"0"=>{"service_operation_id"=>"5"}, 
                  "1"=>{"service_operation_id"=>""}, 
                  "2"=>{"service_operation_id"=>"4"}, 
                  "3"=>{"service_operation_id"=>""},                 
                  "4"=>{"service_operation_id"=>""}}, 
            "kontakt"=>"comment", "Car_id"=>"50"}, 
                      "commit"=>"Dodaj", 
                      "car_id"=>"dw815gn"}

Order has many operation_in_orders
Order has many service_operations through OperationInOrder
OperationInOrder belongs to Order
OperationInOrder belongs to ServiceOperation
ServiceOperation has many operation_in_orders
ServiceOperation has many orders through OperationInOrder

My form:

<%= form_for @order, url: new_car_order_path(@car, @order),  html: {class: "add_order"} do |r| %>
  <%= r.label "Service", class: :add_order_label    %> 
  <% 5.times do %>
  <%= r.fields_for :operation_in_orders do |v| %>

  <%= v.collection_select(:service_operation_id, ServiceOperation.all, :id, :nazwa,include_blank: true) %>
 <!-- <%= v.text_field :order_id, value: @order.id, :style => "display:none" %> -->
  <% end %>
  <% end %>
  <%= r.label "Kontakt", class: :add_order_label %>
  <%= r.text_field :kontakt %>
  <%= r.text_field :Car_id, value: @car.id, :style => "display:none" %>
  <%= r.label " "  %> 
  <%= r.submit "Add", class: "sub" %>
  <%= link_to "Send",ordered_path(car_id: @car.id) ,  class: 'sub'%> 

<% end %>

I have a form where I can choose five ServiceOperations at most to an order and save.
When I save, 5 new OperationInService objects/rows are made.

Is there a possibility to not create those join tables if corresponding field on form is blank?

For example:
I fill only 2 from 5 fields. I save only these two, not 5. Now I save nil values...

I have tried to validate in OperationInService model, but there was an error (rails do not recognize format in controller).

Any ideas?

Answer 1

Update the accepts_nested_form_for method call in Order model as below:

class Order < ActiveRecord::Base
  has_many :operation_in_orders
  accepts_nested_attributes_for :operation_in_orders, reject_if: proc { |attributes| attributes['service_operation_id'].blank? }
  ## ..
end

This way record for operation_in_orders would not be created if service_operation_id is blank.