在ASP.NET MVC 3不显眼的审定与RequiredAttribute标签= AllowEmptyString真 [英] RequiredAttribute with AllowEmptyString=true in ASP.NET MVC 3 unobtrusive validation

问题描述

如果我有 [必需的（AllowEmptyStrings = TRUE）] 在我看来模型声明验证始终触发空输入。我发现<一个href=\"http://www.kevinlabranche.com/blog/CommentView,guid,96448d56-6783-4dcc-a0dd-2a16a6496342.aspx\">the文章，这也解释了为什么它会发生。你知道，如果有可用的解决？如果没有，你怎么处理呢？

If i have [Required(AllowEmptyStrings = true)] declaration in my view model the validation is always triggered on empty inputs. I found the article which explains why it happens. Do you know if there is a fix available? If not, how do you handle it?

推荐答案

的注：我假设你是因为你还使用网络的情况之外的视图模型有AllowEmptyStrings = TRUE;否则它似乎并不像有太大的点到具有必需的属性，允许空字符串在Web场景。的

有三个步骤来处理这个问题：

There are three steps to handle this:

1. 创建一个自定义属性适配器，它补充说，确认参数


2. 注册您的适配器作为一个适配器工厂


3. 重写jQuery验证功能，使空字符串时属性为present

第1步：自定义属性适配器

我修改了RequiredAttributeAdapter在该逻辑地址：

I modified the RequiredAttributeAdapter to add in that logic:

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Web.Mvc;

namespace CustomAttributes
{
    /// <summary>Provides an adapter for the <see cref="T:System.Runtime.CompilerServices.RequiredAttributeAttribute" /> attribute.</summary>
    public class RequiredAttributeAdapter : DataAnnotationsModelValidator<RequiredAttribute>
    {
        /// <summary>Initializes a new instance of the <see cref="T:System.Runtime.CompilerServices.RequiredAttributeAttribute" /> class.</summary>
        /// <param name="metadata">The model metadata.</param>
        /// <param name="context">The controller context.</param>
        /// <param name="attribute">The required attribute.</param>
        public RequiredAttributeAdapter(ModelMetadata metadata, ControllerContext context, RequiredAttribute attribute)
            : base(metadata, context, attribute)
        {
        }
        /// <summary>Gets a list of required-value client validation rules.</summary>
        /// <returns>A list of required-value client validation rules.</returns>
        public override IEnumerable<ModelClientValidationRule> GetClientValidationRules()
        {
            var rule = new ModelClientValidationRequiredRule(base.ErrorMessage);
            if (base.Attribute.AllowEmptyStrings)
            {
                //setting "true" rather than bool true which is serialized as "True"
                rule.ValidationParameters["allowempty"] = "true";
            }

            return new ModelClientValidationRequiredRule[] { rule };
        }
    }
}

第2步：注册这在Global.asax中/的Application_Start（）

    protected void Application_Start()
    {
        AreaRegistration.RegisterAllAreas();

        DataAnnotationsModelValidatorProvider.RegisterAdapterFactory(typeof(RequiredAttribute),
          (metadata, controllerContext, attribute) => new CustomAttributes.RequiredAttributeAdapter(metadata,
            controllerContext, (RequiredAttribute)attribute)); 

        RegisterGlobalFilters(GlobalFilters.Filters);
        RegisterRoutes(RouteTable.Routes);
    }

第3步：覆盖所要求的jQuery验证功能

这是使用jQuery.validator.addMethod（）调用来完成，将我们的定制逻辑，然后调用原有的功能 - 你可以阅读更多关于这种方法的这里。如果你正在使用这个整个网站，也许从你_Layout.cshtml引用的脚本文件。这里是你可以在一个页下降到试验用的样品脚本块：

This is done using the jQuery.validator.addMethod() call, adding our custom logic and then calling the original function - you can read more about this approach here. If you are using this throughout your site, perhaps in a script file referenced from your _Layout.cshtml. Here's a sample script block you can drop in a page to test:

<script>
jQuery.validator.methods.oldRequired = jQuery.validator.methods.required;

jQuery.validator.addMethod("required", function (value, element, param) {
    if ($(element).attr('data-val-required-allowempty') == 'true') {
        return true;
    }
    return jQuery.validator.methods.oldRequired.call(this, value, element, param);
},
jQuery.validator.messages.required // use default message
);
</script>

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