ASP.NET 2.0，PageMethods。

ASP.NET 2.0, PageMethods.

你好，

我使用ASP.NET AJAX PageMethods动态更改标签的文本时一个DropDownList是在我的页面更改。

I'm using ASP.NET AJAX PageMethods to dynamically change the text of a Label when a dropdownlist is changed on my page.

我知道，回发之间将不会保留标签的文本时，他们的客户端，这是我的情况正在发生变化。我听说一个解决办法是保持标签内容在一个隐藏字段，然后在Page_Load中设置该字段标签文本。

I know that the text of Labels are not retained between postbacks when they are changed on client-side, which is my case. I've heard that a solution is to keep the label content in a hidden field, then to set Label text from that field in Page_Load.

但是，这个方案似乎没有真正干净的给我。是否有其他替代方案或最佳做法？

However, this solution does not seem really clean to me. Are there any other alternatives or best practices?

感谢您！

只是为了澄清，我有名字的人一个DropDownList。当DropDownList中得到改变，我想，在一个标签，把那个人的电话。但是，我认为，做一个完整的回发是不是真的是最好的选择，所以我决定得到一个PageMethod的电话，通过在DropDownList检索电话所选项目的ID，而把它的标签。

Just to clarify, I have a dropdownlist with people names. When the dropdownlist get changed, I want, in a label, to put the telephone of that person. However, I thought that doing a full postback was not really the best alternative, so I decided to get the telephone with a PageMethod, passing the Id of the item selected in the dropdownlist to retrieve the telephone, and the put it in the label.

然而，由于其他控件导致完全回传，我失去了对每一个回发的电话。我知道，把它在一个隐藏字段，然后将其设置回在Page_Load中的标签时，有一个完整的回发会的工作，但我wordering如果有另一种解决方案。由于的WebMethods标记为静态的，我不能写Label.text = person.Telephone;在其中。

However, since other controls cause a full postback, I lose the telephone on every postback. I know that putting it in a hidden field, then setting it back to the label in Page_Load when there is a full postback would work, but I was wordering if there was another solution. Since WebMethods are marked as static, I cannot write Label.text = person.Telephone; in them.

推荐答案

至于你似乎有阿贾克斯，你可以只是做一个局部回传，写的号码标签，进入视图状态，并在Page_Load中写入从价值视图状态的标签。

As you seem to have ajax you could just do a partial postback, write the number to the label and into the viewstate, and in page_load write the value from the viewstate to the label.

在DropDownList的事件处理程序：

In the DropDownList eventhandler:

string phone = <.. get phone number ...>;
myLabel.Text = phone;
ViewState["currentPhone"] = phone;

和上pageLoad的：

And on PageLoad:

myLabel.Text = (ViewState["currentPhone"] != null) ? (string)ViewState["currentPhone"] : string.Empty;

如果你不想使用Ajax你可以在你的aspx文件中定义一个HiddenInputField，JavaScript和上回发填充内容填充内容的标签。 在ASPX：

If you don't want to use Ajax you can define a HiddenInputField in your aspx file, fill the content with javascript and on Postback fill the label with the content. On aspx:

<asp:HiddenInputField runat="server" ID="myHiddenInput" />

在pageLoad的：

on PageLoad:

myLabel.Text = myHiddenInput.Text;

可以.value的替代。文中我不知道的时刻。

could be .Value instead of .Text i'm not sure at the moment.