CODEWITHSUNDEEP
c#linq
Edward Tanguay
Edward Tanguay

Reputation: 193282

How to get a custom object out of a List<> with LINQ?

In the example below, why is product null?

using System.Collections.Generic;
using System.Linq;

namespace TestEventsds343
{
    public class Program
    {
        static void Main(string[] args)
        {
            Product product = Product.LoadProduct(222);
        }
    }

    public class Product
    {
        public int ProductNumber { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }

        public static Product LoadProduct(int productNumber)
        {
            List<Product> products = new List<Product>();
            products.Add(new Product { ProductNumber = 111, Name = "Intel CPU", Description = "Newest model, very fast." });
            products.Add(new Product { ProductNumber = 222, Name = "Philips Monitor", Description = "22-inch, very nice." });
            products.Add(new Product { ProductNumber = 333, Name = "Sony Camera", Description = "10 Megapixels, sharp pictures." });

            return products.Where(p => p.ProductNumber == productNumber) as Product;
        }
    }
}

Upvotes: 0

Views: 1846

Answers (2)

TravisWhidden
TravisWhidden

Reputation: 2182

Don't cast it as Product, it already is a product.

return products.Where(p => p.ProductNumber == productNumber).FirstOrDefault()

Null would indicate it doesn't exist, an object returned would be it found something.

Try that.

Upvotes: 1

Stan R.
Stan R.

Reputation: 16065

Where returns an IEnumerable not a single result and using as doesn't throw an exception and just casts it to null, you need to use SingleOrDefault()

return products.Where(p => p.ProductNumber == productNumber).SingleOrDefault();

Upvotes: 6

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