ASP.NET MVC?? ??? ??? ?? ??

ASP.NET MVC? ??? ??? ?? ??? ?? ??? ??? ???? ??? ??? ?????. ??? ??? ??? ???? ?? ??? ?? ?? ???? ??? ??? ?? ??? ???? ? ?? ????.

?: ??? ?? ??

?? ????? ??????. "IsSenior" ??? ??? "Person" ??? ??? ??? "Senior" ??? ????. "IsSenior"? true? ??? ???? "Senior.Description" ??? ?? ??? ??? ????.

??? ?? ??

??? ?????? ??????. ?? ??? ??? ?? ??? ?????.

public class Person
{
    [Required(ErrorMessage = "*")]
    public string Name { get; set; }

    public bool IsSenior { get; set; }

    public Senior Senior { get; set; }
}

public class Senior
{
    [Required(ErrorMessage = "*")]
    public string Description { get; set; }
}

IValidatableObject ???

ASP.NET MVC 3?? IValidatableObject ?????? ???? ??? ??? ??? ?? ? ?? ???? ???????. ??? ? ?????? ???? ValidationContext ?? ??? ???? Validate ???? ???? ???. ? ???? ??? ?? ??? ?? ??? ???? ??? ???? ValidationResult ?? ???? ??? ? ????.

public class Person : IValidatableObject
{
    public string Name { get; set; }
    public bool IsSenior { get; set; }
    public Senior Senior { get; set; }

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        if (IsSenior && String.IsNullOrEmpty(Senior?.Description))
            yield return new ValidationResult("必須提供描述。");
    }
}

IValidatableObject ?????? ?????? ?? "IsSenior" ?? ???? ??? ??? ??? ??? ? ????. "IsSenior"? true? ?? "Senior.Description" ??? ?? ??? ???.

?? ??(C# 6.0 ??)

C# 6.0 ????? ? ?? ??? ???? Validate ???? ???? ? ????.

public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) =>
    IsSenior && String.IsNullOrEmpty(Senior?.Description)
        ? new[] { new ValidationResult("必須提供描述。") }
        : Enumerable.Empty<ValidationResult>();

?? ??? ?? ASP.NET MVC?? ??? ??? ????? ??? ? ????. Senior.Description? ???? ????? null ?? ??? ????? null ??? ???(?.)? ?????.

? ??? ASP.NET MVC?? ??? ??? ??? ???? ??? ??????? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!