Improve cart page rendering:

- Render line_items collection in partial rather than looping
over line_items and rendering the partial multiple times

Fix solidusio#3609

frontend/app/views/spree/orders/_form.html.erb

@@ -10,9 +10,7 @@
  </tr>
  </thead>
  <tbody id="line_items" data-hook>
- <%= order_form.fields_for :line_items do |item_form| %>
- <%= render :partial => 'line_item', :locals => { :variant => item_form.object.variant, :line_item => item_form.object, :item_form => item_form } %>
- <% end %>
+ <%= render partial: 'line_item', collection: order_form.object.line_items, locals: {order_form: order_form} %>
  </tbody>
  <%= render "spree/orders/adjustments" unless @order.adjustments.eligible.blank? %>
 </table>

frontend/app/views/spree/orders/_line_item.html.erb

@@ -1,31 +1,34 @@
-<tr class="<%= cycle('', 'alt') %> line-item">
- <td class="cart-item-image" data-hook="cart_item_image">
- <% if variant.images.length == 0 %>
- <%= link_to small_image(variant.product), variant.product %>
- <% else %>
- <%= link_to image_tag(variant.images.first.attachment.url(:small)), variant.product %>
- <% end %>
- </td>
- <td class="cart-item-description" data-hook="cart_item_description">
- <h4><%= link_to variant.product.name, product_path(variant.product) %></h4>
- <%= variant.options_text %>
- <% if @order.insufficient_stock_lines.include? line_item %>
- <span class="out-of-stock">
- <%= Spree.t(:out_of_stock) %>&nbsp;&nbsp;<br />
- </span>
- <% end %>
- <%= line_item_description(variant) %>
- </td>
- <td class="cart-item-price" data-hook="cart_item_price">
- <%= line_item.single_money.to_html %>
- </td>
- <td class="cart-item-quantity" data-hook="cart_item_quantity">
- <%= item_form.number_field :quantity, :min => 0, :class => "line_item_quantity", :size => 5 %>
- </td>
- <td class="cart-item-total" data-hook="cart_item_total">
- <%= line_item.display_amount.to_html unless line_item.quantity.nil? %>
- </td>
- <td class="cart-item-delete" data-hook="cart_item_delete">
- <%= link_to image_tag('icons/delete.png'), '#', :class => 'delete', :id => "delete_#{dom_id(line_item)}" %>
- </td>
-</tr>
+<% variant = line_item.variant -%>
+<%= order_form.fields_for :line_items, line_item do |item_form| -%>
+ <tr class="<%= cycle('', 'alt') %> line-item">
+ <td class="cart-item-image" data-hook="cart_item_image">
+ <% if variant.images.length == 0 %>
+ <%= link_to small_image(variant.product), variant.product %>
+ <% else %>
+ <%= link_to image_tag(variant.images.first.attachment.url(:small)), variant.product %>
+ <% end %>
+ </td>
+ <td class="cart-item-description" data-hook="cart_item_description">
+ <h4><%= link_to variant.product.name, product_path(variant.product) %></h4>
+ <%= variant.options_text %>
+ <% if @order.insufficient_stock_lines.include? line_item %>
+ <span class="out-of-stock">
+ <%= Spree.t(:out_of_stock) %>&nbsp;&nbsp;<br />
+ </span>
+ <% end %>
+ <%= line_item_description(variant) %>
+ </td>
+ <td class="cart-item-price" data-hook="cart_item_price">
+ <%= line_item.single_money.to_html %>
+ </td>
+ <td class="cart-item-quantity" data-hook="cart_item_quantity">
+ <%= item_form.number_field :quantity, :min => 0, :class => "line_item_quantity", :size => 5 %>
+ </td>
+ <td class="cart-item-total" data-hook="cart_item_total">
+ <%= line_item.display_amount.to_html unless line_item.quantity.nil? %>
+ </td>
+ <td class="cart-item-delete" data-hook="cart_item_delete">
+ <%= link_to image_tag('icons/delete.png'), '#', :class => 'delete', :id => "delete_#{dom_id(line_item)}" %>
+ </td>
+ </tr>
+<% end -%>