aBox shopping cart feature

_cart.html.erb

<%= link_to "My cart: #{current_order.quantity} items",
  current_order_path,
  id: "cart", class: "link item"
%>

_nav.html.erb

<div id="nav" class="ui top stackable fixed menu">
  <%= link_to "aBox", root_path, class: "link item" %>

  <%= form_tag search_path, method: :get, class: "item", style: "width:400px" do %>
    <div class="ui action input">
      <%=
        text_field_tag :search,
        params[:search],
        placeholder: "Search for artists, artwork, or orders"
      %>
      <%= button_tag "Search", type: "submit", name: nil, class: "ui teal basic button" %>
    </div>
  <% end %>

  <div class="right menu">
    <%= render partial: "order_items/cart" %>

    <% if user_signed_in? %>
      <%= link_to "Post artwork", new_artwork_path, class: "link item" %>
      <%= link_to "My profile", profile_path, class: "link item" %>
      <%= link_to "Edit profile", edit_user_registration_path, class: "link item" %>
      <%= link_to "Logout", destroy_user_session_path, method: :delete, class: "link item" %>
    <% else %>
      <%= link_to "Sign up", new_user_registration_path, class: "link item" %>
      <%= link_to "Login", new_user_session_path, class: "link item" %>
    <% end %>
  </div>
</div>

add_to_cart.js.erb

$("#nav #cart").replaceWith("<%= j render partial: 'cart' %>");

order.rb

class Order < ApplicationRecord
  multisearchable against: %i[id]

  validates :status, presence: true

  has_many :order_items, dependent: :destroy
  has_many :artworks, through: :order_items

  def quantity
    sum(:quantity)
  end

  def subtotal
    sum(:artwork_subtotal)
  end

  private

  def sum(method)
    order_items.reduce(0) { |sum, order_item| sum + order_item.public_send(method) }
  end
end

order_item.rb

class OrderItem < ApplicationRecord
  validates :quantity, presence: true

  belongs_to :artwork
  belongs_to :order

  def artwork_subtotal
    artwork.price * quantity
  end
end

order_items_controller.rb

class OrderItemsController < ApplicationController
  def create
    @order = current_order
    @order_item = @order.order_items.new(order_item_params)

    respond_to do |format|
      if @order_item.save
        session[:order_id] = @order.id
        format.js { render file: '/order_items/add_to_cart.js.erb' }
      else
        format.html { render :back }
        format.json { render json: @order_item.errors, status: :unprocessable_entity }
      end

      format.js { render file: '/order_items/add_to_cart.js.erb' }
    end
  end

  private

  def order_item_params
    params.require(:order_item).permit(:quantity, :artwork_id, :order_id)
  end
end

orders_controller.rb

class OrdersController < ApplicationController
  def show
    @order = current_order
  end

  private

  def order_params
    params.require(:order).permit(:status)
  end
end

show.html.erb (artworks)

<p id="notice"><%= notice %></p>

<div class="ui stackable two column grid container">
  <div class="nine wide column">
    <%= image_tag(@artwork.photo, class: "ui large fluid image") %>
  </div>

  <div class="seven wide column">
    <p>
      <strong>Title:</strong>
      <%= @artwork.title %>
    </p>

    <p>
      <strong>Price:</strong>
      <%= number_to_currency @artwork.price %>
    </p>

    <div class="ui divider"></div>

    <%= form_with(model: @order_item) do |form| %>
      <% if @order_item.errors.any? %>
        <div id="error_explanation">
          <h2><%= pluralize(@order_item.errors.count, "error") %> prohibited this order item from being saved:</h2>

          <ul>
          <% @order_item.errors.full_messages.each do |message| %>
            <li><%= message %></li>
          <% end %>
          </ul>
        </div>
      <% end %>

      <%= form.hidden_field :artwork_id, value: @artwork.id %>

      <%= form.label :quantity %>
      <%= form.select(
            :quantity,
            (1..10).collect { |i| i }
          ) %><br><br>

      <%= form.submit "Add to cart", class: "ui teal button" %>
    <% end %>
  </div>
</div>

<div class="ui hidden divider"></div>

<% if current_user == @artwork.gallery.user %>
  <%= link_to 'Edit', edit_artwork_path(@artwork) %> |
<% end %>

<%= link_to 'Back', artworks_path %>

show.html.erb (orders)

<p id="notice"><%= notice %></p>

<% if @order.order_items.empty? %>
  <h1>
    Your Cart is empty.
  </h1>
<% else %>
  <h1>
    Your Cart
  </h1>
  <table class="ui very basic table">
    <thead>
      <tr>
        <th>Artwork Item</th>
        <th>Title</th>
        <th>Price</th>
        <th>Quantity</th>
      </tr>
    </thead>
    <tbody>
      <% @order.order_items.each do |item| %>
        <tr>
          <td>
            <%= link_to item.artwork do %>
              <%= image_tag(item.artwork.photo, display: "inline", class: "ui tiny image") %>
            <% end %>
          </td>
          <td>
            <%= item.artwork.title %><br>
          </td>
          <td>
            Price: <%= number_to_currency(item.artwork.price) %><br>
          </td>
          <td>
            Quantity: <%= item.quantity %>
          </td>
        </tr>
      <% end %>
    </tbody>
  </table>

  <div class="ui divider"></div>
  <div class="ui stackable four column grid container">
    <div class="ui four wide column">
      <strong>Subtotal (<%= @order.quantity %> items):</strong>
      <strong><%= number_to_currency(@order.subtotal) %></strong>
    </div>
    <div class="ui twelve wide column">
      <div class="ui mini button">Proceed to checkout</div><br>
    </div>
  </div>
<% end %>