拉的SelectList信息来源ViewBag：不创造价值=＆QUOT; ...＆QUOT;在生成html [英] SelectList pulling info from ViewBag: not creating value="..." in generated html

问题描述

我想使用的Razor视图引擎打造在MVC4应用程序客户端验证的下拉列表。

I'm trying to create a client-side validated dropdown list in an MVC4 application using the Razor view engine.

在code在视图中产生下拉列表如下：

The code in the view to generate the dropdown list is as follows:

 @Html.DropDownList("Test", new SelectList(ViewBag.AvailableLoBsDescriptions, ViewBag.AvailableLoBsIds), "--none--")

注意ViewBag.AvailableLoBsDescriptions在使用一个IList控制器中创建的，同时也是在控制器使用一个IList创建ViewBag.AvailableLoBsIds。

Note that ViewBag.AvailableLoBsDescriptions is created in the controller using an IList while ViewBag.AvailableLoBsIds is also created in the controller using an IList.

我希望发生的是有剃刀生成一个下拉菜单，说明填充每个内部HTML，而IDS填充值=...。然而，对价值产生什么都没有，结果是这样的：

What I expected to happen is have Razor generate a dropdown menu where Descriptions populates the inner html of each while the Ids populates the value="...". However, there is nothing generated for value at all, resulting in something like this:

<select id="Test" name="Test"><option value="">--none--</option>
<option>N/A</option>
<option>aaaa</option>
<option>bbbb</option>
<option>cccc</option>
<option>dddd</option>
<option>eeee</option>
<option>ffff</option>
</select>

综观选择列表的文档的http://msdn.microsoft.com/en-us/library/system.web.mvc.selectlist%28v=vs.108%29.aspx,在我看来，这应该工作。有没有人有一个想法，为什么没有被除占位符以外的任何生成的值？

Looking at the SelectList documentation, http://msdn.microsoft.com/en-us/library/system.web.mvc.selectlist%28v=vs.108%29.aspx, it seems to me that this should work. Does anyone have an idea why the values are not being generated for anything other than the placeholder?

谢谢！

推荐答案

构造您所使用如下所示：

The constructor you are using looks like the following:

SelectList(IEnumerable, Object)

第二个参数在这里决定了的当前选择的从集合中的第一个参数对象。它并不规定一个对象作为值的列表来使用。

The second parameter here dictates the currently selected object from the collection in the first parameter. It does not dictate an object to use as a list of values.

你应该使用的SelectList（IEnumerable的，字符串，字符串）做。这使您可以通过用于描述和一个值（的IEnumerable 的每个元素的）属性的名称。然后，您可以产生这样的：

What you should be doing is using SelectList(IEnumerable, String, String). This allows you to pass the name of a property (of each element of IEnumerable) to use for the description and one for the value. You can then produce something like this:

控制器：

// Create your IEnumerable
var LoBs = new List<LoB>();

// Assign some parameters to your objects
var exampleItem = new LoB();
exampleItem.Description = "Option text";
exampleItem.Value = "myValue";

// Populate your list and return your view.
LoBs.Add(exampleItem);
ViewBag.LoBs = LoBs;
return View();

查看：

@Html.DropDownList("Test",
    new SelectList(ViewBag.LoBs, "Value", "Description"),
    "--none--")

的Et瞧...

<select id="Test" name="Test">
    <option value="">--none--</option>
    <option value="myValue">Option text</option>
</select>

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