CODEWITHSUNDEEP
ruby-on-railsrubyvariablesruby-on-rails-4sum
Xeen
Xeen

Reputation: 7003

How to sum columns in rails?

  <% @cart.items.each do |item| %>
    <div class="holder">

        <div class="image"><%= link_to (image_tag (item.product.avatar.url(:thumb))), item.product %></div>
        <div class="title"><%= link_to item.product.title, item.product %></div>

        <div class="count"><%= item.count %></div>
        <div class="price"><%= number_to_currency(item.product.price, :unit => '€ ') %></div>
        <div class="description"><%= item.product.description.truncate(110).html_safe %></div>
    </div>
  <% end %>

  <div class="total">Total price: @price</div>

I'd like to get the total sum of item.product.price column for each cart and then display it at the end of the carts list. How can that be done?

Upvotes: 4

Views: 1074

Answers (1)

Beat Richartz
Beat Richartz

Reputation: 9622

You can use arel to achieve this, it avoids loading the items and their products so you wont be hit with as many queries as you have items in your cart:

@cart.items.joins(:product).sum("products.price")

This will lead to a query like:

SELECT SUM(products.price) AS sum_id 
FROM `items` 
INNER JOIN `products` ON `products`.`id` = `items`.`product_id` 
WHERE `items`.`cart_id` = 1

Upvotes: 5

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