使用 ValidationAttribute 的自定义验证不会触发客户端验证

Question

我创建了一个从 ValidationAttribute 派生的自定义验证器。我的理解是它将为客户端脚本生成足够的元数据以自动验证（使用 jquery.validate）。自定义验证器在服务器端工作正常。但它不会在客户端触发错误消息。 （其他默认验证器，如“StringLength”在客户端也可以正常工作。）我们如何纠正它？

public class Person
{
    [Required(ErrorMessage = "First name required")]
    public string FirstName { get; set; }

    [CustomStartLetterMatch("FirstName")]
    [StringLength(5,ErrorMessage = "Must be under 5 characters")]
    public string LastName { get; set; }

    [Range(18,50,ErrorMessage="Must be between 18 and 50")]
    public int Age { get; set; }


}


public sealed class CustomStartLetterMatch : ValidationAttribute
{

    private const string _defaultErrorMessage = " First letter of '{0}' must be same as first letetr of '{1}'";
    private string _basePropertyName;

    public CustomStartLetterMatch(string basePropertyName)
        : base(_defaultErrorMessage)
    {
        _basePropertyName = basePropertyName;
    }


    //Override FormatErrorMessage Method
    public override string FormatErrorMessage(string name)
    {
        return string.Format(_defaultErrorMessage, name, _basePropertyName);
    }


    //Override IsValid
    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        //Get PropertyInfo Object
        var basePropertyInfo = validationContext.ObjectType.GetProperty(_basePropertyName);
        var baseValue = (string)basePropertyInfo.GetValue(validationContext.ObjectInstance, null);
        var currentValue = (string)value;


        string firstLetterBaseValue = baseValue.Substring(0, 1);
        string firstLetterCurrentValue = currentValue.Substring(0, 1);

        //Comparision
        if (!string.Equals(firstLetterBaseValue, firstLetterCurrentValue))
        {
            var message = FormatErrorMessage(validationContext.DisplayName);
            return new ValidationResult(message);
        }

        //Default return - This means there were no validation error
        return null;
    }

}

查看

@model MyValidationTEST.Person

<script src="@Url.Content("~/Scripts/jquery-1.5.1.min.js")" type="text/javascript">  </script>

@*UnObtrusive*@
<script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>




@using (Html.BeginForm()) {
@Html.ValidationSummary(true)
<fieldset>
    <legend>Person</legend>

    <div class="editor-label">
        @Html.LabelFor(model => model.FirstName)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.FirstName)
        @Html.ValidationMessageFor(model => model.FirstName)
    </div>

    <div class="editor-label">
        @Html.LabelFor(model => model.LastName)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.LastName)
        @Html.ValidationMessageFor(model => model.LastName)
    </div>

    <div class="editor-label">
        @Html.LabelFor(model => model.Age)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.Age)
        @Html.ValidationMessageFor(model => model.Age)
    </div>



    <p>
        <input type="submit" value="Create" />
    </p>
</fieldset>
}

<div>
@Html.ActionLink("Back to List", "Index")
</div>

阅读：

1. IValidatableObject in MVC3 - client side validation

2. In ASP.NET MVC3 how do you stay DRY with very similar but slightly different viewmodels?

3. http://odetocode.com/Blogs/scott/archive/2011/02/22/custom-data-annotation-validator-part-ii-client-code.aspx

4. http://bradwilson.typepad.com/blog/2010/10/mvc3-unobtrusive-validation.html

5. ASP.NET MVC 3 client-side validation with parameters

6. How can I have a custom ValidationAttribute rendered as a 'data-val-xx' attribute on the client-side?

7. Clientside Validation in "Self Validate Model" in ASP.NET-MVC3

Answer 1

我的理解是它会为 客户端脚本自动验证（使用 jquery.validate）。

你的理解是错误的。您不可能期望有足够的元数据来生成客户端验证。在这个IsValid 方法中，您绝对可以做任何事情。您甚至可以调用非托管 C++ 库来执行验证。您不可能期望 ASP.NET MVC 3 会在客户端上反映这一点。

如果您想为此类自定义验证逻辑启用客户端验证，则需要实现 IClientValidatable 并添加自定义适配器。在这个适配器中，您必须重新实现您在服务器上执行的相同逻辑，但这次使用的是 javascript。

这里是one example。这是another one。

正如您所看到的，客户端验证在一些简单的规则（例如Required 之类的东西）下可以正常工作，一旦您开始进行一些真正的验证，您就必须自己实现它。