如何获取在列表框项目的"键"在C＃WinForms应用程序？ [英] How do I get at the listbox item's "key" in c# winforms app?

问题描述

我写一个WinForms应用程序中，用户从列表框中选择一个项目和编辑，形成一个关联对象的一部分的一些数据。该编辑，然后从对象列表到底层文件的应用。

I am writing a winforms app in which a user selects an item from a listbox and edits some data that forms part of an associated object. The edits are then applied from the object list to an underlying file.

在ASP.Net比用户看到的是文本显示列表项分配不同的系统值不重要的。在WinForms应用程序，你必须设置的DisplayMember，而在一个稍微更复杂（在互联网上不是经常相关的）过程中每个项目的Valuemember。

In ASP.Net assigning a different system value to a list item than the display text the user sees is trivial. In a winforms app you have to set the "Displaymember" and the "Valuemember" of each item in a slightly more complicated (and not oft related on the internet) process.

这个我已经做了。在调试模式下我已经证实，每个项目现在有一个值是显示屏部件（友好的字符串用户看到）和一个键，valuemember，这是关键的地方要更新的数据的哈希表对象存在。

This I have done. In debug mode I have confirmed that every item now has a value which is the display member (a "friendly" string that the user sees) and a key, the valuemember, which holds the key to a hashtable object where the data to be updated exists.

因此，当用户拿起一个字符串编辑程序应通过钥匙的哈希表，猛拉了对象，并允许编辑发生在它

So when a user picks a string to edit the program should pass the "key" to the hashtable, yank out the object and allow editing to take place upon it.

美中不足的？

我看不到告诉节目看的任何明显的方法项目的valuemember。我天真地期望它填充列表框中的的SelectedValue属性，但是这将是迄今为止太简单了。那么到底如何才能获得到列表项的价值？

I can't see any obvious way of telling the program to look at the item's valuemember. I naively expected it to populate the list box's "SelectedValue" property, but that would be too simple by far. So how the hell do I get to the list item value?

推荐答案

好了，所以答案之际，刘德华的回答的结果，因此，我upvoting这个问题的答案。

Okay so the answer came as a result of Andy's answer, hence my upvoting that answer.

但是当我创建了一个小的类，并试图将列表项投进去该类程序抛出异常。

But when I created a little class and tried to cast the listitem into that class the program threw an exception.

说明问题的异常告诉我，程序无法投出的DictionaryEntry成一个类我已经定义的类型。

Revealingly the exception told me that the program could not cast a DictionaryEntry into a class of the type I had defined.

所以我删除了代理类和重新定义的要求这样的：

So I deleted the proxy class and reframed the request thus:

DictionaryEntry de = (DictionaryEntry)listbox.SelectedItem;

string htKey = de.Key.ToString();

和这一切都很好。

在年底奇怪的是简单的答案。谢谢你的提示安迪。

Bizarrely simple answer in the end. Thanks for the hint Andy.

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