使用 VB.NET 形式的会话变量在页面之间传递值
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/21030565/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Pass values between pages using session variable in VB.NET form
提问by Nita
I am trying to create session variable for 2 items so I can use it between pages. However the variable will be the search results displayed in the form. In the code behind how can I get the value of the control.
我正在尝试为 2 个项目创建会话变量，以便我可以在页面之间使用它。但是，变量将是表单中显示的搜索结果。在后面的代码中，我如何获得控件的值。
aspx page:
aspx页面：
<asp:Label ID="txtdate" runat="server" Text='<%# Eval("Inci_date", "{0:d}")%>'></asp:Label>
VB.NetCode:
VB.Net代码：
Dim strDate As String = ""
If strDate Is Nothing Then
strDate = DirectCast(frmUpdateIncident.FindControl("txtInciDate"), Label).Text
End If
Session("IncidentDate") = strDate
My Varialbe strDate is still empty.
我的 Varialbe strDate 仍然是空的。
回答by Jo?o Pinho
Dim strDate As String = ""
This condition is always false, since "" != Nothing, String.IsNullOrEmpty is better suited to test string emptiness conditions.
此条件始终为假，因为 "" != Nothing，String.IsNullOrEmpty 更适合测试字符串空性条件。
If strDate Is Nothing Then
Also in your label, is your label inside a databing control like GridView?
If no then you cannot set your label text with server side tags, you must use code behind txtDate.Text="abc", maybe in Page_Load.
同样在您的标签中，您的标签是否在像 GridView 这样的数据控件中？如果否，则您无法使用服务器端标签设置标签文本，您必须使用后面的代码txtDate.Text="abc"，也许在 Page_Load 中。
Regards.
问候。
回答by Mych
I would check that it is a date not just not empty using IsDate. So
我会使用 IsDate 检查它是否是一个不为空的日期。所以
Dim strDate As String = ""
If IsDate(txtInciDate.Text) Then
strDate = txtInciDate.Text
End If
Session("IncidentDate") = strDate
