blocks|key|644769|text|我刚刚遇到了这个问题，并通过以下操作简单地解决了它：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|644770|@for(int+i+=+0;+i+<+Model.ToGroups.Count;+i%2B%2B)
{
++++@Html.HiddenFor(model+=>+Model.ToGroups[i])
}|code-block|syntax|javascript|644771|通过使用for而不是foreach，模型绑定将正确工作，并获取列表中的所有隐藏值。这似乎是解决这个问题的最简单的方法。|offset|length|style|CODE|644772|entityMap^0|0|0|4|3|A|7|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

I've just come across this issue and solved it simply by doing the following:
<pre><code>@for(int i = 0; i &lt; Model.ToGroups.Count; i++)
{
 @Html.HiddenFor(model =&gt; Model.ToGroups[i])
}
</code></pre>
By using a <code>for</code> instead of a <code>foreach</code> the model binding will work correctly and pick up all of your hidden values in the list. Seems like the simplest way to solve this problem.

blocks|key|429734|text|HiddenFor与DisplayFor或EditorFor不同。它不适用于集合，只能使用单个值。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|429735|您可以使用MVC+Futures项目中提供的Serialize+HTML帮助器将对象序列化为Hidden字段，否则您必须自己编写代码。更好的解决方案是简单地序列化某种类型的ID，然后在回发时从数据库重新获取数据。|429736|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

HiddenFor is not like a DisplayFor or EditorFor. It won't work with collections, only single values.

You can use the Serialize HTML helper available in the MVC Futures project to serialize an object to a Hidden field, or you will have to write the code yourself. A better solution is to simply serialize an ID of some sort and re-get the data from the database on postback.

blocks|key|644658|text|这有点麻烦，但如果@Html.EditorFor或@Html.DisplayFor适用于你的列表，如果你想确保它在post请求中发送但不可见，你可以只使用display:+none;来隐藏它，例如：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|644659|<div+style="display:+none;">@Html.EditorFor(model+=>+model.MyList)</div>|code-block|syntax|javascript|644660|entityMap^0|9|F|P|G|25|E|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|L|$]]

It's a bit of a hack, but if <code>@Html.EditorFor</code> or <code>@Html.DisplayFor</code> work for your list, if you want to make sure it's sent on the post request but not visible, you could just style it to using <code>display: none;</code> to hide it instead, e.g:

<pre><code>&lt;div style="display: none;"&gt;@Html.EditorFor(model =&gt; model.MyList)&lt;/div&gt;
</code></pre>

blocks|key|644211|text|Html.HiddenFor只为一个值而设计。在创建隐藏字段之前，您需要以某种方式序列化列表。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|644212|例如，如果您的列表是字符串类型，您可以将列表连接到一个逗号分隔的列表中，然后在post返回控制器后拆分该列表。|644213|entityMap^0|0|E|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|N|8|@]|D|@]|E|$]]]|I|$]]

<code>Html.HiddenFor</code> is designed for only one value. You will need to serialize your list in some way before creating the hidden field.

For example, if your list is of type string, you could join the list into a comma separated list, then split the list after post back in your controller.

blocks|key|430244|text|我刚刚发现(经过几个小时的尝试，为什么模型值没有返回到控制器)，隐藏的for应该遵循EditorFor。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|430245|除非我做错了什么，否则这就是我所发现的。我不会再犯同样的错误了。|430246|在包含另一个类的列表的模型的上下文中。|430247|这将不起作用：|430248|++++++++@{
++++++++++++for+(int+i+=+0;+i+<+Model.Categories.Count;+i%2B%2B)
++++++++++++{
++++++++++++++++<tr>
++++++++++++++++++++<td>
++++++++++++++++++++++++@Html.HiddenFor(modelItem+=>+Model.Categories[i].Id)
++++++++++++++++++++++++@Html.HiddenFor(modelItem+=>+Model.Categories[i].ProductCategoryId)
++++++++++++++++++++++++@Html.HiddenFor(modelItem+=>+Model.Categories[i].CategoryName)++++++++++++++++++++++++++++
++++++++++++++++++++++++@Html.DisplayFor(modelItem+=>+Model.Categories[i].CategoryName)++++++++++++++++++++++++++++
++++++++++++++++++++</td>
++++++++++++++++++++<td>
++++++++++++++++++++++++@Html.HiddenFor(modelItem+=>+Model.Categories[i].DailyPurchaseLimit)++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++@Html.EditorFor(modelItem+=>+Model.Categories[i].DailyPurchaseLimit)
++++++++++++++++++++++++@Html.ValidationMessageFor(modelItem+=>+Model.Categories[i].DailyPurchaseLimit)
++++++++++++++++++++</td>
++++++++++++++++++++<td+style="text-align:+center">
++++++++++++++++++++++++@Html.HiddenFor(modelItem+=>+Model.Categories[i].IsSelected)++++++++++++++++++++++++++++
++++++++++++++++++++++++@Html.EditorFor(modelItem+=>+Model.Categories[i].IsSelected)
++++++++++++++++++++</td>
++++++++++++++++</tr>
++++++++++++}
++++++++}|code-block|syntax|javascript|430249|这将会在哪里......|430250|++++++++++++for+(int+i+=+0;+i+<+Model.Categories.Count;+i%2B%2B)
++++++++++++{
++++++++++++++++<tr>
++++++++++++++++++++<td>
++++++++++++++++++++++++@Html.HiddenFor(modelItem+=>+Model.Categories[i].Id)
++++++++++++++++++++++++@Html.HiddenFor(modelItem+=>+Model.Categories[i].ProductCategoryId)
++++++++++++++++++++++++@Html.HiddenFor(modelItem+=>+Model.Categories[i].CategoryName)++++++++++++++++++++++++++++
++++++++++++++++++++++++@Html.DisplayFor(modelItem+=>+Model.Categories[i].CategoryName)++++++++++++++++++++++++++++
++++++++++++++++++++</td>
++++++++++++++++++++<td>
++++++++++++++++++++++++@Html.EditorFor(modelItem+=>+Model.Categories[i].DailyPurchaseLimit)
++++++++++++++++++++++++@Html.HiddenFor(modelItem+=>+Model.Categories[i].DailyPurchaseLimit)++++++++++++++++++++++++++++
++++++++++++++++++++++++@Html.ValidationMessageFor(modelItem+=>+Model.Categories[i].DailyPurchaseLimit)
++++++++++++++++++++</td>
++++++++++++++++++++<td+style="text-align:+center">
++++++++++++++++++++++++@Html.EditorFor(modelItem+=>+Model.Categories[i].IsSelected)
++++++++++++++++++++++++@Html.HiddenFor(modelItem+=>+Model.Categories[i].IsSelected)++++++++++++++++++++++++++++
++++++++++++++++++++</td>
++++++++++++++++</tr>
++++++++++++}|430251|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|V|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|W|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|Y|8|@]|9|@]|A|$K|L]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I've just found out (after a couple of hours of trying to figure out why model values weren't going back to the controller) that hidden for should follow the EditorFor.

Unless I am doing something else wrong this is what I found. I will not make the mistake again.

In the context of a Model that contains a list of another class.

This will NOT work:

<pre><code> @{
 for (int i = 0; i &lt; Model.Categories.Count; i++)
 {
 &lt;tr&gt;
 &lt;td&gt;
 @Html.HiddenFor(modelItem =&gt; Model.Categories[i].Id)
 @Html.HiddenFor(modelItem =&gt; Model.Categories[i].ProductCategoryId)
 @Html.HiddenFor(modelItem =&gt; Model.Categories[i].CategoryName) 
 @Html.DisplayFor(modelItem =&gt; Model.Categories[i].CategoryName) 
 &lt;/td&gt;
 &lt;td&gt;
 @Html.HiddenFor(modelItem =&gt; Model.Categories[i].DailyPurchaseLimit) 
 @Html.EditorFor(modelItem =&gt; Model.Categories[i].DailyPurchaseLimit)
 @Html.ValidationMessageFor(modelItem =&gt; Model.Categories[i].DailyPurchaseLimit)
 &lt;/td&gt;
 &lt;td style="text-align: center"&gt;
 @Html.HiddenFor(modelItem =&gt; Model.Categories[i].IsSelected) 
 @Html.EditorFor(modelItem =&gt; Model.Categories[i].IsSelected)
 &lt;/td&gt;
 &lt;/tr&gt;
 }
 }
</code></pre>

Where as this WILL......

<pre><code> for (int i = 0; i &lt; Model.Categories.Count; i++)
 {
 &lt;tr&gt;
 &lt;td&gt;
 @Html.HiddenFor(modelItem =&gt; Model.Categories[i].Id)
 @Html.HiddenFor(modelItem =&gt; Model.Categories[i].ProductCategoryId)
 @Html.HiddenFor(modelItem =&gt; Model.Categories[i].CategoryName) 
 @Html.DisplayFor(modelItem =&gt; Model.Categories[i].CategoryName) 
 &lt;/td&gt;
 &lt;td&gt;
 @Html.EditorFor(modelItem =&gt; Model.Categories[i].DailyPurchaseLimit)
 @Html.HiddenFor(modelItem =&gt; Model.Categories[i].DailyPurchaseLimit) 
 @Html.ValidationMessageFor(modelItem =&gt; Model.Categories[i].DailyPurchaseLimit)
 &lt;/td&gt;
 &lt;td style="text-align: center"&gt;
 @Html.EditorFor(modelItem =&gt; Model.Categories[i].IsSelected)
 @Html.HiddenFor(modelItem =&gt; Model.Categories[i].IsSelected) 
 &lt;/td&gt;
 &lt;/tr&gt;
 }
</code></pre>

blocks|key|644462|text|我开始深入研究HiddenFor的源代码，我认为您所看到的障碍是您的复杂对象MyList不能隐式转换为类型string，因此框架将您的Model值视为null并将value属性呈现为空。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|644463|entityMap^0|7|9|12|6|1H|6|1V|5|23|4|29|5|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]|$9|Q|A|R|B|C]|$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|G|$]]

I started digging through the source code for <code>HiddenFor</code>, and I think the roadblock you're seeing is that your complex object <code>MyList</code> is not implicitly convertible to type <code>string</code>, so the framework treats your <code>Model</code> value as <code>null</code> and renders the <code>value</code> attribute empty.

blocks|key|644528|text|你可以在这个solution上看一下。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|644529|在EditorTemplate中只放入HiddenFor。|644530|在你的视图中放上这个：@Html.EditorFor(model+=>+model.MyList)|style|CODE|644531|它应该是有效的。|644532|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/4720330/model-containing-list-of-models-mvc-3-razor^0|6|8|0|0|0|B|12|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@$A|U|B|V|1|W]]|C|$]]|$1|D|3|E|5|6|7|X|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|Y|8|@$A|Z|B|10|H|I]]|9|@]|C|$]]|$1|J|3|K|5|6|7|11|8|@]|9|@]|C|$]]|$1|L|3|-4|5|6|7|12|8|@]|9|@]|C|$]]]|M|$N|$5|O|P|Q|C|$R|S]]]]

You can take a look on this <a href="https://stackoverflow.com/questions/4720330/model-containing-list-of-models-mvc-3-razor">solution</a>.

Put only HiddenFor inside the EditorTemplate.

And in your View put this: <code>@Html.EditorFor(model =&gt; model.MyList)</code>

It should works.

blocks|key|430367|text|面临着同样的问题。如果没有for循环，它只发布列表的第一个元素。在遍历for循环后，它可以保存完整的列表并成功发布。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|430368|+@if+(Model.MyList!=+null)
++++{
++++for+(int+i+=+0;+i+<+Model.MyList.Count;+i%2B%2B)
++++++{
++++++++@Html.HiddenFor(x+=>+x.MyList[i])
++++++}
++++}|code-block|syntax|javascript|430369|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Faced the same issue. Without for loop, it only posted the first element of the list. After iterating through for loop, it can keep full list and post successfully.

<pre><code> @if (Model.MyList!= null)
 {
 for (int i = 0; i &lt; Model.MyList.Count; i++)
 {
 @Html.HiddenFor(x =&gt; x.MyList[i])
 }
 }
</code></pre>

blocks|key|430385|text|另一种选择是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|430386|<input+type="hidden"+value=@(string.Join(",",+Model.MyList))+/>|code-block|syntax|javascript|430387|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Another option would be:

<pre><code>&lt;input type="hidden" value=@(string.Join(",", Model.MyList)) /&gt;
</code></pre>

blocks|key|645062|text|用foreach循环代替for循环可能是一个稍微干净一些的解决方案。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|645063|@foreach(var+item+in+Model.ToGroups)
{
++++@Html.HiddenFor(model+=>+item)
}|code-block|syntax|javascript|645064|entityMap^0|1|7|C|3|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

The <code>foreach</code> loop instead of a <code>for</code> loop might be a slightly cleaner solution.

<pre><code>@foreach(var item in Model.ToGroups)
{
 @Html.HiddenFor(model =&gt; item)
}
</code></pre>

blocks|key|430128|text|另一种可能的解决方法是给列表中的每个对象一个ID，然后使用@Html.DropDownListFor(model+=>+model.IDs)并填充一个包含ID的数组。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|430129|entityMap^0|T|15|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

Another possible way to fix this would be to give each object in your List an ID, then use <code>@Html.DropDownListFor(model =&gt; model.IDs)</code> and populate an array which holds the IDs.

blocks|key|430315|text|可能晚了，但我为集合中的隐藏字段创建了扩展方法(使用简单的数据类型项)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|430316|所以就是这样：|430317|///+<summary>
///+Returns+an+HTML+hidden+input+element+for+each+item+in+the+object's+property+(collection)+that+is+represented+by+the+specified+expression.
///+</summary>
public+static+IHtmlString+HiddenForCollection<TModel,+TProperty>(this+HtmlHelper<TModel>+html,+Expression<Func<TModel,+TProperty>>+expression)+where+TProperty+:+ICollection
{
++++var+model+=+html.ViewData.Model;
++++var+property+=+model+!=+null
++++++++++++++++?+expression.Compile().Invoke(model)
++++++++++++++++:+default(TProperty);

++++var+result+=+new+StringBuilder();
++++if+(property+!=+null+&&+property.Count+>+0)
++++{
++++++++for(int+i+=+0;+i+<+property.Count;+i%2B%2B)
++++++++{
++++++++++++var+modelExp+=+expression.Parameters.First();
++++++++++++var+propertyExp+=+expression.Body;
++++++++++++var+itemExp+=+Expression.ArrayIndex(propertyExp,+Expression.Constant(i));

++++++++++++var+itemExpression+=+Expression.Lambda<Func<TModel,+object>>(itemExp,+modelExp);

++++++++++++result.AppendLine(html.HiddenFor(itemExpression).ToString());
++++++++}
++++}

++++return+new+MvcHtmlString(result.ToString());
}|code-block|syntax|javascript|430318|用法很简单，就像：|430319|@Html.HiddenForCollection(m+=>+m.MyList)|430320|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

maybe late, but i created extension method for hidden fields from collection (with simple data type items):

So here it is:

<pre><code>/// &lt;summary&gt;
/// Returns an HTML hidden input element for each item in the object's property (collection) that is represented by the specified expression.
/// &lt;/summary&gt;
public static IHtmlString HiddenForCollection&lt;TModel, TProperty&gt;(this HtmlHelper&lt;TModel&gt; html, Expression&lt;Func&lt;TModel, TProperty&gt;&gt; expression) where TProperty : ICollection
{
 var model = html.ViewData.Model;
 var property = model != null
 ? expression.Compile().Invoke(model)
 : default(TProperty);

 var result = new StringBuilder();
 if (property != null &amp;&amp; property.Count &gt; 0)
 {
 for(int i = 0; i &lt; property.Count; i++)
 {
 var modelExp = expression.Parameters.First();
 var propertyExp = expression.Body;
 var itemExp = Expression.ArrayIndex(propertyExp, Expression.Constant(i));

 var itemExpression = Expression.Lambda&lt;Func&lt;TModel, object&gt;&gt;(itemExp, modelExp);

 result.AppendLine(html.HiddenFor(itemExpression).ToString());
 }
 }

 return new MvcHtmlString(result.ToString());
}
</code></pre>

Usage is as simple as:

<pre><code>@Html.HiddenForCollection(m =&gt; m.MyList)
</code></pre>

I'm using a model that contains a List as a property. I'm populating this list with items i grab from SQL Server. I want the List to be hidden in the view and passed to the POST action. Later on i may want to add more items to this List with jQuery which makes an array unsuitable for expansion later on. Normally you would use 

<pre><code>@Html.HiddenFor(model =&gt; model.MyList)
</code></pre>

to accomplish this functionality, but for some reason the List in POST is always null.

Very simple question, anyone know why MVC behaves like this?

@Html.HiddenFor does not work on Lists in ASP.NET MVC

我正在使用一个包含列表作为属性的模型。我用从SQL Server抓取的项目填充此列表。我希望列表隐藏在视图中，并传递给POST操作。稍后，我可能想用jQuery将更多项添加到这个列表中，这会使数组在以后不适合扩展。通常，您将使用@Html.HiddenFor(model => model.MyList)来实现此功能，但由于某些原因，POST中的列表始终为空。很简单的问题，有人知道MVC为什么会这样

问在ASP.NET MVC中，@Html.HiddenFor不能处理列表
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问在ASP.NET MVC中，@Html.HiddenFor不能处理列表
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