c# – 每次使用新的guid索引时,如何在集合属性上获取验证消息？

在这个示例ASP.Net MVC 4程序中,我有一个用户填写有关赛马的详细信息.比赛有一个名字,以及所涉及的马匹列表.每匹马都有一个名字和一个年龄.

表单使用ajax和javascript来允许此人动态添加和删除马输入字段,然后在按下提交按钮时立即提交.

为了让这个过程变得简单,我使用Matt Lunn制造的html helper.

public static MvcHtmlString EditorForMany<TModel,TValue>(this HtmlHelper<TModel> html,Expression<Func<TModel,IEnumerable<TValue>>> expression,string htmlFieldName = null) where TModel : class
{
    var items = expression.Compile()(html.ViewData.Model);
    var sb = new StringBuilder();

    if (String.IsNullOrEmpty(htmlFieldName))
    {
        var prefix = html.ViewContext.ViewData.TemplateInfo.HtmlFieldPrefix;

        htmlFieldName = (prefix.Length > 0 ? (prefix + ".") : String.Empty) + ExpressionHelper.GetExpressionText(expression);
    }

    foreach (var item in items)
    {
        var dummy = new { Item = item };
        var guid = Guid.NewGuid().ToString();

        var memberExp = Expression.MakeMemberAccess(Expression.Constant(dummy),dummy.GetType().GetProperty("Item"));
        var singleItemExp = Expression.Lambda<Func<TModel,TValue>>(memberExp,expression.Parameters);

        sb.Append(String.Format(@"<input type=""hidden"" name=""{0}.Index"" value=""{1}"" />",htmlFieldName,guid));
        sb.Append(html.EditorFor(singleItemExp,null,String.Format("{0}[{1}]",guid)));
    }

    return new MvcHtmlString(sb.ToString());
}

虽然我不了解所有细节(请阅读博客文章),但我知道它将索引值更改为guids而不是顺序整数.这允许我删除列表中间的项目,而无需重新计算索引.

这是我的MCVE的其余代码

HomeController.cs

public class HomeController : Controller
{
    [HttpGet]
    public ActionResult Index()
    {
        var model = new Race();

        //start with one already filled in
        model.HorsesInRace.Add(new Horse() { Name = "Scooby",Age = 10 });

        return View(model);
    }

    [HttpPost]
    public ActionResult Index(Race postedModel)
    {
        if (ModelState.IsValid)
            //model is valid,redirect to another page
            return RedirectToAction("ViewHorseListing");
        else
            //model is not valid,show the page again with validation errors
            return View(postedModel);
    }

    [HttpGet]
    public ActionResult AjaxMakeHorseEntry()
    {
        //new blank horse for ajax call
        var model = new List<Horse>() { new Horse() };
        return PartialView(model);
    }
}

Models.cs

public class Race
{
    public Race() { HorsesInRace = new List<Horse>(); }

    [Display(Name = "Race Name"),Required]
    public string RaceName { get; set; }

    [Display(Name = "Horses In Race")]
    public List<Horse> HorsesInRace { get; set; }
}

public class Horse
{
    [Display(Name = "Horse's Name"),Required]
    public string Name { get; set; }

    [Display(Name = "Horse's Age"),Required]
    public int Age { get; set; }
}

Index.cshtml

@model CollectionAjaxPosting.Models.Race
<h1>Race Details</h1>
@using (Html.BeginForm())
{
    @Html.ValidationSummary()
    <hr />
    <div>
        @Html.DisplayNameFor(x => x.RaceName)
        @Html.EditorFor(x => x.RaceName)
        @Html.ValidationMessageFor(x => x.RaceName)
    </div>
    <hr />
    <div id="horse-listing">@Html.EditorForMany(x => x.HorsesInRace)</div>
    <button id="btn-add-horse" type="button">Add New Horse</button>
    <input type="submit" value="Enter Horses" />
}

<script type="text/javascript">
    $(document).ready(function () {

        //add button logic
        $('#btn-add-horse').click(function () {
            $.ajax({
                url: '@Url.Action("AjaxMakeHorseEntry")',cache: false,method: 'GET',success: function (html) {
                    $('#horse-listing').append(html);
                }
            })
        });

        //delete-horse buttons
        $('#horse-listing').on('click','button.delete-horse',function () {
            var horseEntryToRemove = $(this).closest('div.horse');
            horseEntryToRemove.prev('input[type=hidden]').remove();
            horseEntryToRemove.remove();
        });

    });
</script>

查看/共享/ EditorTemplates / Horse.cshtml

@model CollectionAjaxPosting.Models.Horse

<div class="horse">
    <div>
        @Html.DisplayNameFor(x => x.Name)
        @Html.EditorFor(x => x.Name)
        @Html.ValidationMessageFor(x => x.Name)
    </div>
    <div>
        @Html.DisplayNameFor(x => x.Age)
        @Html.EditorFor(x => x.Age)
        @Html.ValidationMessageFor(x => x.Age)
    </div>
    <button type="button" class="delete-horse">Remove Horse</button>
    <hr />
</div>

查看/主页/ AjaxMakeHorseEntry.cshtml

@model IEnumerable<CollectionAjaxPosting.Models.Horse>

@Html.EditorForMany(x => x,"HorsesInRace")

数据流与此代码一起使用.一个人能够在页面上尽可能多地创建和删除马条目,并且在提交表单时,所有输入的值都被赋予操作方法.

但是,如果用户未输入马条目的[必需]信息,则ModelState.IsValid将显示为false,同时显示该表单,但不会显示Horse属性的验证消息.验证错误确实显示在ValidationSummary列表中.

例如,如果将“种族名称”留空,并且还有一个“马”的名称,则会显示前者的验证消息.后者将进行验证< span>使用“field-validation-valid”类.

我非常确定这是因为EditorForMany方法在每次创建页面时为每个属性创建新的guid,因此验证消息无法与正确的字段匹配.

我该怎么做才能解决这个问题？我是否需要放弃guid索引创建,还是可以对EditorForMany方法进行更改以允许验证消息正确传递？

public static class HtmlHelperExtensions
{
    public static MvcHtmlString EditorForMany<TModel,IEnumerable<TValue>>> propertyExpression,Expression<Func<TValue,string>> indexResolverExpression = null,string htmlFieldName = null) where TModel : class
    {
        htmlFieldName = htmlFieldName ?? ExpressionHelper.GetExpressionText(propertyExpression);

        var items = propertyExpression.Compile()(html.ViewData.Model);
        var htmlBuilder = new StringBuilder();
        var htmlFieldNameWithPrefix = html.ViewData.TemplateInfo.GetFullHtmlFieldName(htmlFieldName);
        Func<TValue,string> indexResolver = null;

        if (indexResolverExpression == null)
        {
            indexResolver = x => null;
        }
        else
        {
            indexResolver = indexResolverExpression.Compile();
        }

        foreach (var item in items)
        {
            var dummy = new { Item = item };
            var guid = indexResolver(item);
            var memberExp = Expression.MakeMemberAccess(Expression.Constant(dummy),dummy.GetType().GetProperty("Item"));
            var singleItemExp = Expression.Lambda<Func<TModel,propertyExpression.Parameters);

            if (String.IsNullOrEmpty(guid))
            {
                guid = Guid.NewGuid().ToString();
            }
            else
            {
                guid = html.AttributeEncode(guid);
            }

            htmlBuilder.Append(String.Format(@"<input type=""hidden"" name=""{0}.Index"" value=""{1}"" />",htmlFieldNameWithPrefix,guid));

            if (indexResolverExpression != null)
            {
                htmlBuilder.Append(String.Format(@"<input type=""hidden"" name=""{0}[{1}].{2}"" value=""{1}"" />",guid,ExpressionHelper.GetExpressionText(indexResolverExpression)));
            }

            htmlBuilder.Append(html.EditorFor(singleItemExp,guid)));
        }

        return new MvcHtmlString(htmlBuilder.ToString());
    }
}

public class Race
{
    public Race() { HorsesInRace = new List<Horse>(); }

    [Display(Name = "Race Name"),Required]
    public int Age { get; set; }

    // Note the addition of Index here.
    public string Index { get; set; }
}

<div id="horse-listing">@Html.EditorForMany(x => x.HorsesInRace,x => x.Index)</div>

@Html.EditorForMany(x => x,x => x.Index,"HorsesInRace")

[HttpGet]
public ActionResult AjaxMakeHorseEntry()
{
    var model = new Race();

    model.HorsesInRace.Add(new Horse());
    return PartialView(model);
}

@model Models.Race

@Html.EditorForMany(x => x.HorsesInRace,x => x.Index)