Ruby 在轨道上：如何在 ajax 购物车中更改购物车中的数量项目，购物车保存在 session，而不是数据库？

Question

UPDATE: i found solution for my problems. Thanks for your support!

I'm doing simple shopping cart with ajax by ruby on rails.

I want to ajax my cart page when change quantity item of cart. I found some solutions but they save cart into database. How to resolve my solution without save cart into database?

I wonder:

• Can i use ajax in file view or include ajax file in view? As way i tried in PHP?
• If i use ajax default on rails, how to render input field(change value) in file increment/decrement_item.js.erb (file render partial without reload page)? I don't use cart as active record, so render @cart or @item is impossible(or i dont know how to make it possible).

I also have some idea for my problem. But it's so hard. Exp: I think i will create a _quantity_item display input quantity. And i can use it for index view of cart and render in increment/decrement.js.erb but fail. So sad!

My view display cart(short):

<% @cart.each_with_index do |item, index| %>
      <tr>
        <th scope="row"><%= index %></th>
        <td><img src="<%= asset_path(item[0].image) %>" style="width:100px"></td>
        <td><%= item[0].name %></td>
        <td><%= money_vn_format(item[0].price) %></td>
        <td>
          <div class="quantity">
            <%= button_to '-', decrement_item_path(item[0].id), class: 'btn minus1', method: :put, remote: true %>
           <input class="quantity" min="0" value="<%= item[1] %>" type="number"> 
             <%= button_to '+', increment_item_path(item[0].id), class: 'btn add1', method: :put, remote: true %>
          </div>
        </td>
        <td><%= money_vn_format(item[0].price * item[1]) %></td>
        <td><%= link_to 'Remove', delete_cart_path(item[0].id) %></td>
      </tr>
    <% end %>

and code CartsController:

# frozen_string_literal: true

class CartsController < ApplicationController
  def index
    save_session_to_cart if session.key? :cart
  end

  def add
    session[:cart] ||= {}
    session[:cart][params[:id]] = 1 unless session[:cart].key? params[:id]
    save_session_to_cart

    redirect_to carts_index_path
  end

  def delete
    session[:cart].delete params[:id]
    redirect_to carts_index_path
  end

  def destroy
    reset_session
    redirect_to carts_index_path
  end

  def increment_item
    session[:cart][params[:id]] += 1
    save_session_to_cart
    redirect_to carts_index_path
  end

  def decrement_item
    session[:cart][params[:id]] -= 1 if session[:cart][params[:id]] > 1
    save_session_to_cart
    redirect_to carts_index_path
  end

  private

  def save_session_to_cart
    @cart = []
    @total = 0
    session[:cart].each do |product_id, quantity|
      @cart << [Product.find(product_id), quantity]
      @total += Product.find(product_id).price * quantity
    end
    @cart
  end
end

Answer 1

Check out this answer by crispychicken Rails: How to store data in session? . The poster suggests playing around with the session variable in rails.

Or conversely if you want it to be simpler, make use of the browser's local storage using JS.

Answer 2

I'd do that using the browser's local storage, with javascript. You can save values with this:

localStorage.setItem('items-count', 1);

And read them back like this:

localStorage.getItem('items-count');

But bare in mind that if the user opens a different browser or uses another device, the shopping cart will be empty.