Validate Data annotation attribute from C#

Validate Data annotation attribute from C# manually.

Create validation method :

public static IEnumerable<string> Validate(params object[] objects)

{

   foreach (var item in objects)

   {               

     PropertyInfo[] properties = item.GetType().GetProperties();

     foreach (var propertyInfo in properties)

     {

       object[] customAttributes = propertyInfo.GetCustomAttributes(

typeof(ValidationAttribute),

inherit: true);

       foreach (var customAttribute in customAttributes)

       {

         var validationAttribute = (ValidationAttribute)customAttribute;

         bool isValid = validationAttribute.IsValid(propertyInfo.GetValue(item,     

                                                   BindingFlags.GetProperty,

   null,

   null,

   null));

         if (!isValid)

         {

           yield return validationAttribute.ErrorMessage;

         }

       }

     }

   }

}

Add DTO class :

    public class TestClass1

    {

        [Required(ErrorMessage = "This field is required")]

        [EmailAddress(ErrorMessage = "Please enter valid email address")]

        public string Email { get; set; }

        [Range(0, 10, ErrorMessage = "Value between 0 to 10")]

        public int Num1 { get; set; }

        public TestClass2 TestClass2 { get; set; }

    }

    public class TestClass2

    {

        [Required(ErrorMessage = "FirstName is required")]

        public string FirstName { get; set; }

    }

Now use validation method in real code :

TestClass1 tc = new TestClass1();

            tc.Email = "AP@"; // Please enter valid email address

            tc.Num1 = 50; // Value between 0 to 10

            tc.TestClass2 = new TestClass2(); // FirstName is required

            var messages =  Validate(tc, tc.TestClass2);

            StringBuilder sb = new StringBuilder();

            foreach (var item in messages)

            {

                sb.AppendLine(item);

            }