自定義屬性來驗證，如果郵件是在asp.net mvc的獨特

Question

我有以下型號

public partial class OwnerData 
{ 
    public string firstname { get; set; } 
    public string lastname { get; set; } 

    [Required] 
    [StringLength(60)] 
    [EmailAddress] 
    [MailNotExists] //this is a custom function 
    public string email { get; set; } 
} 

自定義功能MailNotExists如下

namespace MyApp.CustomDataAnnotations 
{ 
    public class MailNotExists : ValidationAttribute 
    { 
     protected override ValidationResult IsValid(object value, ValidationContext validationContext) 
     { 
      DbContext db = new DbContext(); 

      var user = db.Users.FirstOrDefault(u => u.email == (string)value); 

      if (user == null) 
       return ValidationResult.Success; 
      else 
       return new ValidationResult("Mail already exists"); 
     } 
    } 
} 

該模型被用來進查看給用戶更改郵件的可能性，槽

@Html.EditorForModel(); 

html輸出返回到編輯器也是現有的郵件，如果你想改變它，系統首先檢查郵件是否已經存在於db通過驗證器[MailNotExists]並且一切正常。唯一的問題是，如果用戶不想更改郵件，但只需要名字或姓氏，然後提交表單，驗證器將返回錯誤，因爲郵件已存在。

任何解決方案如何旁路驗證程序只在該特定情況下？

Answer 1

那麼它有點特殊，因爲我沒有看到主鍵，但我會做下一個方法添加主鍵所有者數據

public partial class OwnerData 
     { 
      public int Id { get; set; } 
      public string firstname { get; set; } 
      public string lastname { get; set; } 

      [Required] 
      [StringLength(60)] 
      [EmailAddress] 
      [MailNotExists] //this is a custom function 
      public string email { get; set; } 
     } 

和修改屬性

protected override ValidationResult IsValid(object value, ValidationContext validationContext) 
     { 
      var owner = validationContext.ObjectInstance as OwnerData; 
      if(owner == null) return new ValidationResult("Model is empty"); 
      DbContext db = new DbContext(); 
      var user = db.Users.FirstOrDefault(u => u.email == (string) value && u.id != owner.Id); 

      if (user == null) 
       return ValidationResult.Success; 
      else 
       return new ValidationResult("Mail already exists"); 
     }