using System;

​

using FluentValidation;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

    public interface INamedItem {

        string Name{ get; }

    }

    public class Customer:INamedItem {

        public string Name { get; set; }

    }

    public class CustomerValidator : AbstractValidator<INamedItem>

    {

  public CustomerValidator()

  {

    RuleFor(x => x.Surname).NotEmpty();

    RuleFor(x => x.Forename).NotEmpty().WithMessage("Please specify a first name");

    RuleFor(x => x.Discount).NotEqual(0).When(x => x.HasDiscount);

    RuleFor(x => x.Address).Length(20, 250);

    RuleFor(x => x.Postcode).Must(BeAValidPostcode).WithMessage("Please specify a valid postcode");

  }

​

  private bool BeAValidPostcode(string postcode)

  {

    // custom postcode validating logic goes here

  }

}

}