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

??? ?? ??? ?? ??? ?? ??? ??? ??? ??? ? ???? ?????. ASP.NET MVC??? ValidationAttribute ?? ???? ???? ??? ?? ??? ?? ??? ??? [Validate] ??? ???? ??? ??? ??? ? ????.

??? ?? ??? ?? ??? ?? ??? ?? ??

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

public class CombinedMinLengthAttribute : ValidationAttribute
{
    public CombinedMinLengthAttribute(int minLength, params string[] propertyNames)
    {
        this.PropertyNames = propertyNames;
        this.MinLength = minLength;
    }

    public string[] PropertyNames { get; private set; }
    public int MinLength { get; private set; }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        var properties = this.PropertyNames.Select(validationContext.ObjectType.GetProperty);
        var values = properties.Select(p => p.GetValue(validationContext.ObjectInstance, null)).OfType<string>();
        var totalLength = values.Sum(x => x.Length) + Convert.ToString(value).Length;

        if (totalLength < MinLength)
        {
            return new ValidationResult(ErrorMessageString);
        }

        return ValidationResult.Success;
    }
}

??? ??

? ??? ??? ??? ????? ?? ?? ? ??? [Validate] ???? ??? ? ????.

public class MyViewModel
{
    [CombinedMinLength(20, "Bar", "Baz", ErrorMessage = "Foo, Bar和Baz屬性的組合最小長(zhǎng)度應(yīng)大于20")]
    public string Foo { get; set; }
    public string Bar { get; set; }
    public string Baz { get; set; }
}

? ??? ?? ??? Foo, Bar ? Baz ??? ??? ??? ??? ?? ??(? ???? 20)?? ??? ??? ?????. ??? ??? ???? ErrorMessage ?? ??? ??? ?? ??? ?? ??? ??? ?? ???? ?????.

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