会话对象不更新ASP.NET

I set a session object at one juncture in my code:

我在代码的一个时刻设置了一个会话对象:

Session("my_name") = "Dave"

Later in my code I give the user a chance to update this object:

稍后在我的代码中,我给用户一个更新此对象的机会:

Session("my_name") = TextBox1.Text

I reload my page and display a little hello statement like this:

我重新加载我的页面并显示一个像这样的小问候:

Label1.Text = "Hello" & CStr(Session("my_name"))

The result is: "Hello Dave" no matter what I change Session("my_name") too.

结果是:“Hello Dave”无论我改变Session(“my_name”)也是如此。

EDIT: Here is the a full code-behind I wrote up to demonstrated:

编辑:这是我写的一个完整的代码隐藏演示:

Public Class WebForm1
Inherits System.Web.UI.Page

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    Response.Cache.SetCacheability(HttpCacheability.NoCache)
    Response.ExpiresAbsolute = DateTime.Now.AddMonths(-1)
    If Page.IsPostBack = False Then
        Session("my_name") = "Dave"
    End If
    Label1.Text = CStr(Session("my_name"))
End Sub

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
    Session("my_name") = TextBox1.Text
End Sub

End Class

3 个解决方案

#1

The Page's Load event fires up sooner than the Button's click event. Therefore, at the time it runs, the value of Session("my_name") is still "Dave".

Page的Load事件比Button的click事件更快启动。因此,在运行时,Session(“my_name”)的值仍然是“Dave”。

If you'd like to set it up correctly, you should either put the Label1.Text = CStr(Session("my_name")) into the PreRender event handler of your page.

如果您想正确设置它,您应该将Label1.Text = CStr(Session(“my_name”))放入页面的PreRender事件处理程序中。

You cut put it into the Button's Click event as well (after setting the session value, of course), but I guess that you want to use the session later for storing objects for less trivial purposes.

你也把它放入了Button的Click事件中(当然,在设置了会话值之后),但我想你以后想要使用会话来存储对象,以减少不重要的目的。

(I guess that you'd like to use the session for more advanced purposes later. After all, what would be the point of using session if you only want to change a label's text?)

(我想你以后想要将会话用于更高级的目的。毕竟,如果你只想更改标签的文本,那么使用会话会有什么意义?)

Basically, here is what you want:

基本上,这就是你想要的:

• The Page_Load sets Session("my_name") to "Dave" if it is not a postback

如果不是回发,则Page_Load将Session(“my_name”)设置为“Dave”

• The Button1_Click sets Session("my_name") to the textbox's text

Button1_Click将Session(“my_name”)设置为文本框的文本

• The Page_PreRender sets the label's text.

Page_PreRender设置标签的文本。

Here's what's happening with your current code:

以下是您当前代码所发生的情况:

• The Page_Load sets Session("my_name") to "Dave" if it is not a postback

如果不是回发,则Page_Load将Session(“my_name”)设置为“Dave”

• The Page_Load sets the label's text

Page_Load设置标签的文本

• The Button1_Click sets Session("my_name") to the textbox's text

Button1_Click将Session(“my_name”)设置为文本框的文本

You can read more about the topic in here: ASP.NET Page Life Cycle Overview.

您可以在此处阅读有关该主题的更多信息:ASP.NET页面生命周期概述。

#2

The Page.Load runs before your Button1_Click - so you are setting the value of your textbox to whatever you have in session, and then a bit later taking the contents of that textbox (which you have already overwritten) and popping it back into session.

Page.Load在您的Button1_Click之前运行 - 因此您将文本框的值设置为会话中的任何内容,然后稍后获取该文本框的内容(已经覆盖)并将其弹回到会话中。

#3

You're not setting your Session variable default properly. Basically you're setting the session variable to 'Dave' on every page load that's not a postback. That even includes callbacks and page reloads.

您没有正确设置Session变量的默认值。基本上你是在每次页面加载时将会话变量设置为'Dave'而不是回发。这甚至包括回调和页面重新加载。

To set the Session default try...

要设置会话默认尝试...

if( String.IsNullOrEmpty(Session["my_name"]) )
{
    Session["my_name"] = "Dave";
}

Now you can use your session variable without testing if it's part of a Postback or Callback.

现在,您可以使用会话变量而不进行测试,如果它是回发或回调的一部分。