Distinct not working with LINQ to Objects

Question

class Program
{
    static void Main(string[] args)
    {
        List books = new List 
        {
            new Book
            {
                


        

Answer 1

You can use extension method on list which checks uniqueness based on computed Hash. You can also change extension method to support IEnumerable.

Example:

public class Employee{
public string Name{get;set;}
public int Age{get;set;}
}

List employees = new List();
employees.Add(new Employee{Name="XYZ", Age=30});
employees.Add(new Employee{Name="XYZ", Age=30});

employees = employees.Unique(); //Gives list which contains unique objects. 

Extension Method:

    public static class LinqExtension
        {
            public static List Unique(this List input)
            {
                HashSet uniqueHashes = new HashSet();
                List uniqueItems = new List();

                input.ForEach(x =>
                {
                    string hashCode = ComputeHash(x);

                    if (uniqueHashes.Contains(hashCode))
                    {
                        return;
                    }

                    uniqueHashes.Add(hashCode);
                    uniqueItems.Add(x);
                });

                return uniqueItems;
            }

            private static string ComputeHash(T entity)
            {
                System.Security.Cryptography.SHA1CryptoServiceProvider sh = new System.Security.Cryptography.SHA1CryptoServiceProvider();
                string input = JsonConvert.SerializeObject(entity);

                byte[] originalBytes = ASCIIEncoding.Default.GetBytes(input);
                byte[] encodedBytes = sh.ComputeHash(originalBytes);

                return BitConverter.ToString(encodedBytes).Replace("-", "");
            }