使用DataAnnotations比较两个模型属性

Question

我如何编写一个比较两个字段的自定义ValidationAttribute？这是常见的"输入密码","确认密码"方案.我需要确保两个字段相同并保持一致,我想通过DataAnnotations实现验证.

所以在伪代码中,我正在寻找一种方法来实现如下所示:

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

    [Required]
    [Display(Name = "Re-type Password")]
    [Compare(CompareField = Password, ErrorMessage = "Passwords do not match")]
    public string PasswordConfirm { get; set; }
}

public class CompareAttribute : ValidationAttribute
{
    public CompareAttribute(object propertyToCompare)
    {
        // ??
    }

    public override bool IsValid(object value)
    {
        // ??
    }
}

所以问题是,我如何编码[Compare] ValidationAttribute？

Answer 1

确保您的项目引用system.web.mvc v3.xxxxx.

然后你的代码应该是这样的:

using System.Web.Mvc;

....

[Required(ErrorMessage = "This field is required.")]    
public string NewPassword { get; set; }

[Required(ErrorMessage = "This field is required.")]
[Compare(nameof(NewPassword), ErrorMessage = "Passwords don't match.")]
public string RepeatPassword { get; set; }

Answer 2

ASP.NET MVC 3 Framework中有一个CompareAttribute来执行此操作.如果您正在使用ASP.NET MVC 2并以.Net 4.0为目标,那么您可以查看ASP.NET MVC 3源代码中的实现.

Answer 3

这是Darin答案的较长版本:

public class CustomAttribute : ValidationAttribute
{    
    public override bool IsValid(object value)
    {
        if (value.GetType() == typeof(Foo))
        {
           Foo bar = (Foo)value;
           //compare the properties and return the result
        }

        throw new InvalidOperationException("This attribute is only valid for Foo objects");
    }
}

和用法:

[MetadataType(typeof(FooMD))]
public partial class Foo
{
     ... functions ...
}

[Custom]
public class FooMD
{
     ... other data annotations ...
}

错误将显示在 @Html.ValidationSummary(false)