Retrieving data after postback

  • Thread starter Thread starter Guest
  • Start date Start date
G

Guest

If have an asp.net page (code behind written in VB.NET) which needs to store
information from a postback in an arraylist and retain this list across
multiple postbacks.

The variable is declared at the class level as:

Public files As New ArrayList

And I am accessing it in two event procedures. (fileList is an ap:listbox
control and fileUploadBox is an HtmlInputFile control with runat="server"):

Private Sub addFile_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles addFile.Click
If IsPostBack And fileUploadBox.Value <> "" Then
files.Add(fileUploadBox)
fileList.Items.Add(fileUploadBox.PostedFile.FileName)
End If
End Sub

Private Sub removeFile_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles removeFile.Click
If fileList.Items.Count <> 0 And fileList.SelectedIndex <> -1 Then
files.RemoveAt(fileList.SelectedIndex)
fileList.Items.Remove(fileList.SelectedItem.Text)
End If
End Sub

The addFile_Click procedure works fine and the files arraylist is updated;
however, when the removeFile_Click procedure runs the files arraylist is
always empty.

I thought that the contents of any global variables was automatically
maintained across postbacks but this doesn't seems to be working. How can I
do this?

Many thanks for any help.

Alan
 
Alan,

Being public has nothing to do with life time. You need to save it in either
a session variable or in the application cache. Or make it static. Or
repopulate it on every postback. Or put it into viewstate. Many choices.

Eliyahu
 
Thanks for the advice. Got it sorted now.

Alan

Eliyahu Goldin said:
Alan,

Being public has nothing to do with life time. You need to save it in either
a session variable or in the application cache. Or make it static. Or
repopulate it on every postback. Or put it into viewstate. Many choices.

Eliyahu
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