MVC模型自定义控件属性

Question

我正在使用自定义uniqueemail确认属性，如

public class UniqueEmailAttribute : ValidationAttribute
{
    public override bool IsValid(object value)
    {
        WMContext db = new WMContext();
        var userWithTheSameEmail = db.Users.SingleOrDefault(
            u => u.email == (string)value);
        return userWithTheSameEmail == null;
    }

}

插入用户时工作正常。但是，当我尝试更新用户时，它会出错。

public class User
{
    public int userID { get; set; }

    [Required]
    [Display(Name = "Name")]
    public string name { get; set; }

    [Required]
    [Display(Name = "Email")]
    [UniqueEmail(ErrorMessage = "This email is used by another user")]
    public string email { get; set; }
}

解决方案：我已经改变了这样的IsValid方法：

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        var model = (User)validationContext.ObjectInstance;
        WMContext db = new WMContext();
        var userWithTheSameEmail = db.Users.SingleOrDefault(
            u => u.email == (string)value && u.userID!=model.userID);
        if (userWithTheSameEmail!=null)
        {
            return new ValidationResult("Bu eposta adresi kullanılıyor.");
        }
        return ValidationResult.Success;
    }