有型无ViewData的项目'的IEnumerable＆LT; SelectListItem＆GT;'这有钥匙'XXX' [英] There is no ViewData item of type 'IEnumerable<SelectListItem>' that has the key 'xxx'

问题描述

有一对夫妇在Stack Overflow上这个职位，但没有一个答案，似乎修复我目前的状况的问题。

There are a couple of posts about this on Stack Overflow but none with an answer that seem to fix the problem in my current situation.

我在这一个表的页面时，每行有一些文本字段和一个下拉的。所有下拉菜单需要使用相同的SelectList的数据，所以我已经将它设置如下：

I have a page with a table in it, each row has a number of text fields and a dropdown. All the dropdowns need to use the same SelectList data so I have set it up as follows:

控制器

ViewData["Submarkets"] = new SelectList(submarketRep.AllOrdered(), "id", "name");

查看

<%= Html.DropDownList("submarket_0", (SelectList)ViewData["Submarkets"], "(none)") %>

我用的正是这种建立在很多地方，但由于某种原因在这期特别我得到的错误：

I have used exactly this setup in many places, but for some reason in this particular view I get the error:

有型'的IEnumerable具有关键submarket_​​0没有ViewData的项目。

推荐答案

好了，答案是从对这个问题的一些其他职位派生，它是：

Ok, so the answer was derived from some other posts about this problem and it is:

如果你的的ViewData 包含的SelectList 使用相同的名称的DropDownList 即submarket_​​0时，HTML辅助会自动填充您的的DropDownList 与该数据如果您不指定第二个参数在这种情况下是源的SelectList

If your ViewData contains a SelectList with the same name as your DropDownList i.e. "submarket_0", the Html helper will automatically populate your DropDownList with that data if you don't specify the 2nd parameter which in this case is the source SelectList.

发生了什么事与我的错误是：

What happened with my error was:

由于含有下拉列表表是在一个局部视图和的ViewData 已被更改，不再包含在的SelectList 我曾引用了的HtmlHelper （而不是抛出一个错误）试图找到所谓的submarket_​​0选择列表中的ViewData（GRRRR！）它STILL不可能发现，然后就抛出一个错误：）

Because the table containing the drop down lists was in a partial view and the ViewData had been changed and no longer contained the SelectList I had referenced, the HtmlHelper (instead of throwing an error) tried to find the SelectList called "submarket_0" in the ViewData (GRRRR!!!) which it STILL couldnt find, and then threw an error on that :)

请纠正我，如果我错了

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