TIL: The new Keyword Doesn't Hide Data Annotations

In another episode of I thought I knew enough about C#… Today I wanted to “overwrite” the validations of a property from a parent DTO on its child DTO. Let’s say I had a Movie and Clip and needed shorter names for clips. Just take a look at the attributes on Movie and ShortClip. using System.ComponentModel.DataAnnotations; namespace TestProject1; [TestClass] public class NewKeywordTests { public abstract class Movie { [Required] [MinLength(52)] // <-- public string? Name { get; set; } } public class ShortClip : Movie { [MaxLength(20)] // <-- Different annotations public new string? Name { get; set; } // ^^^ } [TestMethod] public void NewDoesNotHideValidationAttributes() { var myClip = new ShortClip { Name = "AShortName" // ^^^^^ // It has less than 20 chars, // so it must be valid, right? }; var context = new ValidationContext(myClip); var validationResults = new List<ValidationResult>(); bool isValid = Validator.TryValidateObject( myClip, context, validationResults,…

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