Accessing Model ID inside of rails form helper

Question

First off I'm new to rails, I have a join table Menus_orders which I'm trying to load ID's into on create.

I have this form helper which has access to Order.new(:id, :name) fields and fields_for Menus_order(:menu_id, :order_id). I can insert the menu_id from a select but I can't for the life of me figure out how to populate a hidden input with the current order_id which the form holds in @order.

look at ORDER_ID HERE

<div class="form">
<h1>Create a new order</h1>
  <%= form_for @order do |f| %>
  <%= f.label :name%><br>
  <%= f.text_field :name%><br>
  <h3>Select meals</h3>
  <%= fields_for(@menus_order) do |i| %>
    <div class="field">
      <%= i.select :menu_id, options_for_select(Menu.all.pluck(:id)) %>
      <%= i.hidden_field :order_id, :value =>   ORDER_ID HERE   %>
    </div>
  <% end %>
  <br>
  <%= f.submit "Create"%><br>
  <% end %>
</div>

Thanks, DW

Answer 1

You should use nested attributes for order model just apply the conventions right & it will be handled, you can achieve this by following example :

order.rb should be like :

class Order < ActiveRecord::Base
  has_many :menu_orders
  accepts_nested_attributes_for :menu_orders
end

menu_order.rb be like :

class MenuOrder < ActiveRecord::Base
belongs_to :order
end

orders/new.html

<div class="form">
<h1>Create a new order</h1>
  <%= form_for @order do |f| %>
  <%= f.label :name%><br>
  <%= f.text_field :name%><br>
  <h3>Select meals</h3>
  <%= f.fields_for :menu_orders do |i| %>
    <div class="field">
      <%= i.select :menu_id, options_for_select(Menu.all.pluck(:id)) %>
    </div>
  <% end %>
  <br>
  <%= f.submit "Create"%><br>
  <% end %>
</div>

OrdersController

class OrdersController < ApplicationController

  def new
    @order = Order.new
    @order.menu_orders.build
  end

  def create
    @order = Order.new(order_params)
    if @order.save
      redirect_to orders_path
      flash[:success] = "Order created"
    else
      render 'new'
    end
  end

  private

  def order_params
    params.require(:order).permit(:name, menu_orders_attributes: [ :menu_id, :order_id ])
  end
end