Need help about List<T>

Question

Hi,

I've class as following,

Product.cs

using System;  
using System.Collections.Generic;  
using System.Linq;  
using System.Threading.Tasks;  
  
namespace Training12042022.ViewModels  
{  
    public class Product  
    {  
        public int Id { get; set; }  
        public string Title { get; set; }  
        public string UrlImage { get; set; }  
        public string Detail { get; set; }  
        public decimal Price { get; set; }  
  
    }  
  
  
}  
  

Cart.cs

using System;  
using System.Collections.Generic;  
using System.Linq;  
using System.Threading.Tasks;  
  
namespace Training12042022.ViewModels  
{  
    public class Cart  
    {  
        public Product Product { get; set; }  
        public int Quantity { get; set; }  
    }  
}  
  

I don't know how to access item in List<Cart>. Need help

So far, I've this

public IActionResult Index()  
        {  
            var _Product = _contextECommerceDB.Product.ToList();  
            ViewBag.Product = _Product;  
  
            var cart = HttpContext.Session.GetString("cart");//get key cart  
            if (cart != null)  
            {  
                List<Cart> dataCart = JsonConvert.DeserializeObject<List<Cart>>(cart);  
  
                if (dataCart.Count == 1)  
                {  
                    ViewBag.NoOfCart = dataCart.Count.ToString() + " product";  
                }  
                else   
                {  
                    ViewBag.NoOfCart = dataCart.Count.ToString() + " products";  
                }  
  
            }  
            else  
            {  
                ViewBag.NoOfCart = "0 product";  
            }  
  
  
            return View();  
        }  

How to access data

1. Product(Id)
2. Product(Title)
3. Quantity

And so on ?

Please help

Answer 1

Hi @Jerry Lipan ,

How to access data
Product(Id)
Product(Title)
Quantity
And so on ?

To access the Product from the Cart, you could use foreach or for loop statement to loop through the list, then access the value from the navigation property (the Product property in the Cart class).

Refer the following code:

Controller:

    public IActionResult CartIndex()  
    {  
        //get the cart data:  
        List<Cart> datacart = _datarepo.GetCarts();  

        //use foreach or for statement to loop the list  
        foreach (var item in datacart)  
        {  
            Console.WriteLine("Product Id: {0} Product Title: {1} Quantity: {2}", item.Product.Id, item.Product.Title, item.Quantity.ToString());  
        }  

        return View(datacart);  
    }  

If you want to access the value in the view page, the code like this:

[Note] In the View page, if you want to list and update the value first, and then submit the updated the value to the controller, in this scenario, you'd better use for loop statement to display the page model data.

@model IEnumerable<MVCWebApp.Models.Cart>  
  
@{  
    ViewData["Title"] = "CartIndex";  
}  
  
<table class="table">  
    <thead>  
        <tr>  
            <th>Product Id</th>  
            <th>Product Title</th>  
            <th>  
                @Html.DisplayNameFor(model => model.Quantity)  
            </th>  
            <th></th>  
        </tr>  
    </thead>  
    <tbody>  
@foreach (var item in Model) {  
        <tr>  
            <td>  
                 @Html.DisplayFor(modelItem => item.Product.Id)  
            </td>  
            <td>  
                 @Html.DisplayFor(modelItem => item.Product.Title)  
            </td>  
            <td>  
                @Html.DisplayFor(modelItem => item.Quantity)  
            </td>  
            <td>  
                @Html.ActionLink("Edit", "Edit", new { /* id=item.PrimaryKey */ }) |  
                @Html.ActionLink("Details", "Details", new { /* id=item.PrimaryKey */ }) |  
                @Html.ActionLink("Delete", "Delete", new { /* id=item.PrimaryKey */ })  
            </td>  
        </tr>  
}  
    </tbody>  
</table>  

The output like this:

---

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Best regards,
Dillion

Answer 2

@Jerry Lipan :

You can cast the List to an array and then use a for loop to iterate over the List and get the respective details of the object Product.

for(int i=0;i<dataCart.Count;i++)  
{  
   var productId  = dataCart.ToArray()[i].Product.Id;  
   var productDetail  = dataCart.ToArray()[i].Product.Detail;  
}  

Answer 3

Hi @Sudipta Chakraborty - MSFT , Hi @Zhi Lv - MSFT

I'm still confuse. How to sum ( Quantity ) ? Some Product have Quantity = 1. Some Product, Quantity = 2. See this data,

json data as following,

[{"Product":{"Id":1,"Title":"Spider-Man: No Way Home","UrlImage":"1.png","Detail":"xxxxxx","Price":103.50},"Quantity":2},{"Product":{"Id":3,"Title":"Shang-Chi: Legend Of The Ten Rings","UrlImage":"3.png","Detail":"zzzzzz","Price":102.40},"Quantity":1},{"Product":{"Id":2,"Title":"The Eternals","UrlImage":"2.png","Detail":"yyyyyy","Price":102.40},"Quantity":1}]  

I want to sum ( Quantity )

Please help

Answer 4

First off, this does not make sense, one product which means Quantity is always going to be 1

public class Cart  
{  
    public Product Product { get; set; }  
    public int Quantity { get; set; }  
}  

Should be

public class Cart  
{  
    public List<Product> Products { get; set; }  
    public int Quantity { get; set; }  
}  

But I'll stay with what you presented in a small example excluding some properties done in a unit test.

public class Product  
{  
    public int Id { get; set; }  
    public string Title { get; set; }  
    public decimal Price { get; set; }  
}  
  
public class Cart  
{  
    public Product Product { get; set; }  
    public int Quantity { get; set; }  
}  
  
public class DataOperations  
{  
    private static string _FileName = Path.Combine(  
        AppDomain.CurrentDomain.BaseDirectory, "carts.json");  
  
    public static void CreateCart()  
    {  
        List<Cart> cartList = new List<Cart>();  
  
        Cart cart1 = new()  
        {  
            Quantity = 1,  
            Product = new Product  
            {  
                Id = 9,  
                Title = "Chai tea",  
                Price = 18m  
            }  
        };  
  
  
        Cart cart2 = new()  
        {  
            Quantity = 1,  
            Product = new Product  
            {  
                Id = 24,  
                Title = "Irish tea",  
                Price = 4m  
            }  
        };  
  
        cartList.AddRange(new[] { cart1, cart2 });  
  
        var json = JsonConvert.SerializeObject(cartList, Formatting.Indented);  
        File.WriteAllText(_FileName, json);  
    }  
  
    public static List<Cart> GetCarts() =>   
        JsonConvert.DeserializeObject<List<Cart>>(File.ReadAllText(_FileName));  
}  

Run the above

[TestMethod]  
[TestTraits(Trait.PlaceHolder)]  
public void TestMethod1()  
{  
      
  
    DataOperations.CreateCart();  
  
    var dataCart = DataOperations.GetCarts();  
  
    Console.WriteLine($"Count: {dataCart.Count}");  
  
    foreach (var cart in dataCart)  
    {  
        Console.WriteLine($"{cart.Product.Id,-3}{cart.Product.Title,-15}{cart.Product.Price:C}");  
    }  
  
    Console.WriteLine($"Total: {dataCart.Sum(x => x.Product.Price):C}");  
      
}  

Answer 5

Thanks to all. My problem has been solved