ValidationModulesValidation for .NET, written at build time

Example ​

using ValidationModules.Constraints;

public sealed class SignUp
{
    [Required, EmailAddress]
    public string? Email { get; init; }

    [Required, StringLength(40, Min = 3)]
    public string? DisplayName { get; init; }

    [Range(18, 120)]
    public int Age { get; init; }
}

The generator writes SignUpValidator from these attributes. Validating new SignUp { Email = "not-an-email", DisplayName = "", Age = 12 } with it returns three errors:

What it does ​

• The generator checks your declarations as it reads them. An attribute on the wrong kind of member, a regular expression that does not parse, or a length whose minimum is above its maximum is a build error.
• Each error has a field path, a stable code, a message and a severity. Code that reacts to errors can key on the code, and translations can replace the message.
• The validators contain no reflection, so they work in trimmed and Native AOT applications.
• Most attributes share their names with System.ComponentModel.DataAnnotations, such as [Required], [StringLength] and [Range]. Models that already use DataAnnotations attributes compile as they are.
• Companion packages validate ASP.NET Core minimal API arguments, check options when the host starts, and supply translated messages.

Packages ​