使用asp.net MVC的 HtmlHelper 时遇到的小问题，报错:Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions.

异常信息：Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions

解决办法：

由以下代码：
@foreach (var item in Model)
{
    @Html.DisplayFor(m => !item.IsIdle, "BoolIcon")
}
改为：

@foreach (var item in Model)
{
    var active = !item.IsIdle;
    @Html.DisplayFor(m => active , "BoolIcon")
}

或者

由以下代码：

<div class="controls" style="width:20%">
@{ int index = @Model.chapter_index + 1;}
@Html.TextBoxFor(model => index, new { @class = "span11" })
</div>

改为：

<div class="controls" style="width:20%">
@{ int index = @Model.chapter_index + 1;}
@Html.TextBoxFor(model => index, new { @class = "span11" })
</div>