I’ve come back to rails after ignoring it for a few years and seem to have forgotten some things!

I have three models:
customer
product
order

When submitting an order, there are two fields to select the customer and the product. However, the logs (and db) show that the customer (customer.email) and product (product.title) is not submitted (just the IDs).

I’m fairly sure it’s something with the associations, but can’t work it out.

Order.rb

class Order < ApplicationRecord
    belongs_to :customer
    belongs_to :product 

    accepts_nested_attributes_for :customer
    accepts_nested_attributes_for :product

    validates :customer, presence: true
    validates :product, presence: true
    validates :quantity, presence: true

    
    def total_price
        product.price * quantity
    end
end

product.rb

class Product < ApplicationRecord
    has_many :orders, dependent: :destroy
end

customer.rb

class Customer < ApplicationRecord
    has_many :orders, dependent: :destroy
end

orders_controller

class OrdersController < ApplicationController
  before_action :set_order, only: %i[ show edit update destroy ]

  # GET /orders or /orders.json
  def index
    @orders = Order.includes(:product, :customer).all  
  end

  # GET /orders/1 or /orders/1.json
  def show
    @order = Order.includes(:product, :customer).find(params[:id])
  end

  # GET /orders/new
  def new
    @order = Order.new
  end

  # GET /orders/1/edit
  def edit
  end

  # POST /orders or /orders.json
  def create
    @order = Order.new(order_params)

    respond_to do |format|
      if @order.save
        format.html { redirect_to order_url(@order), notice: "Order was successfully created." }
        format.json { render :show, status: :created, location: @order }
      else
        format.html { render :new, status: :unprocessable_entity }
        format.json { render json: @order.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /orders/1 or /orders/1.json
  def update
    respond_to do |format|
      if @order.update(order_params)
        format.html { redirect_to order_url(@order), notice: "Order was successfully updated." }
        format.json { render :show, status: :ok, location: @order }
      else
        format.html { render :edit, status: :unprocessable_entity }
        format.json { render json: @order.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /orders/1 or /orders/1.json
  def destroy
    @order.destroy!

    respond_to do |format|
      format.html { redirect_to orders_url, notice: "Order was successfully destroyed." }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_order
      @order = Order.find(params[:id])
    end

    # Only allow a list of trusted parameters through.
    def order_params
      params.require(:order).permit(:product, :customer, :quantity, :product_id, :customer_id, :price, customer_attributes: [:id, :email], produc_attributes: [:id, :title])
    end
end

_form

<%= form_with(model: order) do |form| %>
  <% if order.errors.any? %>
    <div style="color: red">
      <h2><%= pluralize(order.errors.count, "error") %> prohibited this order from being saved:</h2>

      <ul>
        <% order.errors.each do |error| %>
          <li><%= error.full_message %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

  <div>
    <%= form.label :product, style: "display: block" %>
    <%= form.collection_select :product_id, Product.all, :id, :title, prompt: "Select Product" %>
  </div>

  <div>
    <%= form.label :customer, style: "display: block" %>
    <%= form.collection_select :customer_id, Customer.all, :id, :email, prompt: "Select Customer" %>
  </div>

  <div>
    <%= form.label :quantity, style: "display: block" %>
    <%= form.number_field :quantity %>
  </div>

  <div>
    <%= form.submit %>
  </div>
<% end %>
``` (