Build Shopping Cart with Session in ASP.NET Core MVC 5

Create ASP.NET Core MVC 5 Project

On the Visual Studio, select Create a new project from Get Started

Select ASP.NET Core Web Application

Input Project Name and select Location for new project

Select ASP.NET Core 5.0 Version and select ASP.NET Core Empty Template. Click Create button to finish

Add Image Files

Create new folder named images in wwwroot folder. Copy images need to use in project to images folder.

Add Configurations

Open Startup.cs file and add new configurations as below:

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace LearnASPNETCoreMVC5
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllersWithViews();

            services.AddSession();
        }

        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseSession();

            app.UseStaticFiles();

            app.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Demo}/{action=Index}/{id?}");
            });

        }
    }
}

Entities Class

Create new folder named Models. In Models folder, create new entities class as below:

Product Entity

Create new class named Product.cs as below:

namespace LearnASPNETCoreMVC5.Models
{
    public class Product
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public double Price { get; set; }
        public string Photo { get; set; }
    }
}

Item Entity

Create new class named Item.cs as below:

namespace LearnASPNETCoreMVC5.Models
{
    public class Item
    {
        public Product Product { get; set; }

        public int Quantity { get; set; }
    }
}

Create Session Helper

Create new folder named Helpers. In this folder, create new helper named SessionHelper.cs as below:

using Microsoft.AspNetCore.Http;
using Newtonsoft.Json;

namespace LearnASPNETCoreMVC5.Helpers
{
    public static class SessionHelper
    {
        public static void SetObjectAsJson(this ISession session, string key, object value)
        {
            session.SetString(key, JsonConvert.SerializeObject(value));
        }

        public static T GetObjectFromJson<T>(this ISession session, string key)
        {
            var value = session.GetString(key);
            return value == null ? default(T) : JsonConvert.DeserializeObject<T>(value);
        }
    }
}

Create Controller

Create new folder named Controllers. In this folder, create new controllers as below:

ProductController

Create new class named ProductController.cs as below:

using LearnASPNETCoreMVC5.Models;
using Microsoft.AspNetCore.Mvc;

namespace LearnASPNETCoreMVC5.Controllers
{
    [Route("product")]
    public class ProductController : Controller
    {
        [Route("")]
        [Route("index")]
        [Route("~/")]
        public IActionResult Index()
        {
            var productModel = new ProductModel();
            ViewBag.products = productModel.findAll();
            return View();
        }
    }
}

CartController

Create new class named CartController.cs as below:

using LearnASPNETCoreMVC5.Helpers;
using LearnASPNETCoreMVC5.Models;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.Linq;

namespace LearnASPNETCoreMVC5.Controllers
{
    [Route("cart")]
    public class CartController : Controller
    {
        [Route("index")]
        public IActionResult Index()
        {
            var cart = SessionHelper.GetObjectFromJson<List<Item>>(HttpContext.Session, "cart");
            ViewBag.cart = cart;
            ViewBag.total = cart.Sum(item => item.Product.Price * item.Quantity);
            return View();
        }

        [Route("buy/{id}")]
        public IActionResult Buy(string id)
        {
            ProductModel productModel = new ProductModel();
            if (SessionHelper.GetObjectFromJson<List<Item>>(HttpContext.Session, "cart") == null)
            {
                List<Item> cart = new List<Item>();
                cart.Add(new Item { Product = productModel.find(id), Quantity = 1 });
                SessionHelper.SetObjectAsJson(HttpContext.Session, "cart", cart);
            }
            else
            {
                List<Item> cart = SessionHelper.GetObjectFromJson<List<Item>>(HttpContext.Session, "cart");
                int index = isExist(id);
                if (index != -1)
                {
                    cart[index].Quantity++;
                }
                else
                {
                    cart.Add(new Item { Product = productModel.find(id), Quantity = 1 });
                }
                SessionHelper.SetObjectAsJson(HttpContext.Session, "cart", cart);
            }
            return RedirectToAction("Index");
        }

        [Route("remove/{id}")]
        public IActionResult Remove(string id)
        {
            List<Item> cart = SessionHelper.GetObjectFromJson<List<Item>>(HttpContext.Session, "cart");
            int index = isExist(id);
            cart.RemoveAt(index);
            SessionHelper.SetObjectAsJson(HttpContext.Session, "cart", cart);
            return RedirectToAction("Index");
        }

        private int isExist(string id)
        {
            List<Item> cart = SessionHelper.GetObjectFromJson<List<Item>>(HttpContext.Session, "cart");
            for (int i = 0; i < cart.Count; i++)
            {
                if (cart[i].Product.Id.Equals(id))
                {
                    return i;
                }
            }
            return -1;
        }

    }
}

Create View

Create new folder named Views. In this folder, create new views as below:

Product View

Create new folder named Product. In Product folder, create new view named Index.cshtml as below:

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
</head>
<body>

    <h3>Products List</h3>
    <table cellpadding="2" cellspacing="2" border="1">
        <tr>
            <th>Id</th>
            <th>Name</th>
            <th>Photo</th>
            <th>Price</th>
            <th>Buy</th>
        </tr>
        @foreach (var product in ViewBag.products)
        {
            <tr>
                <td>@product.Id</td>
                <td>@product.Name</td>
                <td><img src="~/images/@product.Photo" width="60" /> </td>
                <td>@product.Price</td>
                <td align="center">
                    <a asp-controller="cart" asp-action="buy" asp-route-id="@product.Id">Buy Now</a>
                </td>
            </tr>
        }
    </table>

</body>
</html>

Cart Views

Create new folder named Cart. In Cart folder, create new view named Index.cshtml as below:

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
</head>
<body>

    <h3>Cart Page</h3>
    <table cellpadding="2" cellspacing="2" border="1">
        <tr>
            <th>Option</th>
            <th>Id</th>
            <th>Name</th>
            <th>Photo</th>
            <th>Price</th>
            <th>Quantity</th>
            <th>Sub Total</th>
        </tr>
        @foreach (var item in ViewBag.cart)
        {
            <tr>
                <td><a asp-controller="cart" asp-action="remove" asp-route-id="@item.Product.Id">Remove</a></td>
                <td>@item.Product.Id</td>
                <td>@item.Product.Name</td>
                <td><img src="~/images/@item.Product.Photo" width="60" /> </td>
                <td>@item.Product.Price</td>
                <td>@item.Quantity</td>
                <td>@(item.Product.Price * item.Quantity)</td>
            </tr>
        }
        <tr>
            <td align="right" colspan="6">Sum</td>
            <td>
                @ViewBag.total
            </td>
        </tr>
    </table>
    <br>
    <a asp-controller="product" asp-action="index">Continue Shopping</a>

</body>
</html>

Create Razor View Imports

Select Views folder and right click to select Add\New Item Menu

Select Web\ASP.NET in left side. Select Razor View Imports item and click Add button to Finish

In _ViewImports.cshtml file and TagHelpers library as below:

@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

Structure of ASP.NET Core MVC 5 Project

Run Application

Access Index action in Product controller with following url: http://localhost:48982

Output

Click Buy Now link from product page to buy a product and show it in cart page