using System;

using FluentValidation;

​

​

public class Entity

{

    public string HasMaterialPublishedElseWhereText { get; set; }

    public string DtPublishedTimeText { get; set; }

}

​

public class EntityValidator : AbstractValidator<Entity>

{

    public EntityValidator()

    {

        RuleSet("Rule1", () =>

            {

                RuleFor(x => x.DtPublishedTimeText)

                    .NotEmpty()

                        .When(HasMaterialPublishedElseWhereText)

                        .WithMessage("Required Field")

                    .Must(BeAValidDate)

                        .WithMessage("Must be date");

            });

        RuleSet("Rule2", () =>

            {

                RuleFor(x => x.DtPublishedTimeText)

                    .NotEmpty()

                        .WithMessage("Required Field")

                    .Must(BeAValidDate)

                        .WithMessage("Must be date")

                        .When(HasMaterialPublishedElseWhereText);

            });

    }

    private bool BeAValidDate(string val)

    {

        DateTime date;

        return  DateTime.TryParse(val, out date);

    }

    private bool HasMaterialPublishedElseWhereText(Entity model)

    {

        return model.HasMaterialPublishedElseWhereText != null && 

                 model.HasMaterialPublishedElseWhereText.Equals("yes");

    }       

}

​

public class Program

{

    public static void Main()

    {

        var entityValidator = new EntityValidator(); 

        var yesEntity = 

            new Entity

            {   

                HasMaterialPublishedElseWhereText = "yes",

                DtPublishedTimeText = "2015-10-23"

            };

        var noEntity = 

            new Entity

            {   

                HasMaterialPublishedElseWhereText = "no",

                DtPublishedTimeText = "---"

            };      

​

        var yesResult = entityValidator.Validate(yesEntity, ruleSet: "Rule1");

        var noResult = entityValidator.Validate(noEntity, ruleSet: "Rule1");

        Console.WriteLine("Rule1 yesEntity valid: " + yesResult.IsValid);

        foreach (var error in yesResult.Errors)

        {

            Console.WriteLine("   Error: " + error.ErrorMessage);

        }

        Console.WriteLine("Rule1 noEntity valid: " + noResult.IsValid);

        foreach (var error in noResult.Errors)

        {

            Console.WriteLine("   Error: " + error.ErrorMessage);

        }

        Console.WriteLine();

        Console.WriteLine();

        yesResult = entityValidator.Validate(yesEntity, ruleSet: "Rule2");

        noResult = entityValidator.Validate(noEntity, ruleSet: "Rule2");

        Console.WriteLine("Rule2 yesEntity valid: " + yesResult.IsValid);

        foreach (var error in yesResult.Errors)

        {

            Console.WriteLine("   Error: " + error.ErrorMessage);

        }

        Console.WriteLine("Rule2 noEntity valid: " + noResult.IsValid);

        foreach (var error in noResult.Errors)

        {

            Console.WriteLine("   Error: " + error.ErrorMessage);

        }   

    }

}