c# – 将输入数据库的电子邮件地址与DataAnnotations进行比较

发布时间：2020-12-16 02:00:11 所属栏目：百科来源：网络整理

导读：我在MVC的模型中有一个类： public class NewModel{ public bool AllComplexes { get; set; } public int UserID { get; set; } public int? RoleID { get; set; } public int ComplexID { get; set; } [Required(ErrorMessage = "Please enter a user name.

我在MVC的模型中有一个类：

public class NewModel
{
    public bool AllComplexes { get; set; }
    public int UserID { get; set; }
    public int? RoleID { get; set; }
    public int ComplexID { get; set; }

    [Required(ErrorMessage = "Please enter a user name."),StringLength(50)]
    public string Username { get; set; }

    [Required(ErrorMessage = "Please enter Password"),StringLength(100,ErrorMessage = "Password cannot be longer than 100 characters")]
    public string Password { get; set; }

    [Compare("Password",ErrorMessage = "Passwords do not match")]
    [Required(ErrorMessage = "Please confirm Password")]
    public string RetypePassword { get; set; }

    [RegularExpression( "^[a-z0-9_+-]+(.[a-z0-9_+-]+)*@[a-z0-9-]+(.[a-z0-9]+)*.([a-z]{2,4})$",ErrorMessage = "Invalid email format." )]
    [Required(ErrorMessage = "Please enter your e-mail address."),StringLength(50)]
    public string Email { get; set; }

    public List<NEWCategoryModel> Categories { get; set; }
    //public List<NEWPrivilegeModel> userPrivList { get; set; }
    public List<DropDownItem> ComplexList { get; set; }
    public List<DropDownItem> RoleList { get; set; }
    public string NewRole { get; set; }

    public NewModel()
    {

    }
}

输入的电子邮件地址存储在：

public string Email { get; set; }

我需要使用Data Annotation将该电子邮件地址与存储在数据库中的所有电子邮件地址进行比较.我想我需要一个自定义数据注释？但我不知道该怎么做.

这是从数据库获取电子邮件地址的查询示例：

db.ContactInformations.Where(x => x.EMail != null).Select(x => x.EMail);

解决方法

public class NewModel 
{
      [EmailValidation(ErrorMessage = "The Email Address already exists")]
      [RegularExpression( "^[a-z0-9_+-]+(.[a-z0-9_+-]+)*@[a-z0-9-]+(.[a-z0-9]+)*.([a-z]{2,ErrorMessage = "Invalid email format." )]
      [Required(ErrorMessage = "Please enter your e-mail address."),StringLength(50)]
      public string Email { get; set; }
{


public class EmailValidation : ValidationAttribute
{

    protected override ValidationResult IsValid(object value,ValidationContext validationContext)
    {
        PropmetEntities db = new PropmetEntities();
        if (value != null)
        {
            var valueAsString = value.ToString();
            IEnumerable<string> email = db.ContactInformations.Where(x => x.EMail != null).Select(x => x.EMail);
            if (email.Contains(valueAsString))
            {
                var errorMessage = FormatErrorMessage(validationContext.DisplayName);
                return new ValidationResult(errorMessage);
            }
        }
        return ValidationResult.Success;
    }
}

（编辑：李大同）

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