[RESOLVED] keep user input available through gridview paging

[VBnewbeee]

Hi, I'm trying to cache user's input avail through gridview paging. I receive error System.NullReferenceException was unhandled by user code
Message="Object reference not set to an instance of an object." Any thought is appreciated. Thank you in advance.

When I walked through CacheData, it seems to cache the data just fine. However, sd is empty.

 Private Sub CacheData()
        Dim row As GridViewRow
        Dim sd1 As New StringDictionary
        Dim count As Integer = 0
        For Each row In GridView1.Rows
            Dim txtRoomNum As TextBox = CType(row.FindControl("RoomNumber"), TextBox)
            Dim lblID As Label = CType(row.FindControl("RetreatantID"), Label) 'a way to identify the row, I use primary key. This would be a template column
            sd1.Add(lblID.Text, txtRoomNum.Text)
        Next

        Dim index As String = GridView1.PageIndex
        Cache.Insert("cachedRMAssignValues" & index, sd1)
    End Sub

    Private Sub setCachedEdit()
        Dim sd As StringDictionary = Cache.Get("cachedRMAssignValues" & GridView1.PageIndex)
        Dim de As New DictionaryEntry
        Dim r As GridViewRow

        If sd.Count > 0 Then 
            For Each de In sd
                For Each r In GridView1.Rows
                    Dim txtRoomNum As TextBox = CType(r.FindControl("RoomNumber"), TextBox)
                    Dim lblID As Label = CType(r.FindControl("RetreatantID"), Label)
                    Dim index As String = GridView1.PageIndex
                    If lblID.Text = de.Key Then
                        txtRoomNum.Text = de.Value
                    End If
                Next
            Next
        End If
    End Sub

Here's my GridView Paging:

 Protected Sub GridView1_PageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs)
        Dim rpData As New clsACData
        Dim groupID As String = Session("groupID")
        If GridView1.EditIndex <> -1 Then
            e.Cancel = True
        End If

        If (dlSearchOptions.SelectedValue = "recruiter name" Or dlSearchOptions.SelectedValue = "retreatant name" Or dlSearchOptions.SelectedValue = "retreatant not assigned a room" Or dlSearchOptions.SelectedValue = "special needs") Then
            CacheData()
            GridView1.PageIndex = e.NewPageIndex
            GridView1.DataSource = SortDataTable(rpData.RetreatantsForRMAssign(getSearchOptions(), getInput(), groupID), True)
            GridView1.DataBind()
            setCachedEdit()

        ElseIf (dlSearchOptions.SelectedValue = "registration status") Then
            CacheData()
            GridView1.DataSource = SortDataTable(rpData.RetreatantsForRMAssign(getSearchOptions(), getRegStatus(), groupID), True)
            GridView1.PageIndex = e.NewPageIndex
            GridView1.DataBind()
            setCachedEdit()

        ElseIf (dlSearchOptions.SelectedValue = "building") Then
            CacheData()
            GridView1.DataSource = SortDataTable(rpData.RetreatantsForRMAssign(getSearchOptions(), getRegBuilding(), groupID), True)
            GridView1.PageIndex = e.NewPageIndex
            GridView1.DataBind()
            setCachedEdit()

        End If

[mendhak]

Went through your code, it looks like it should work, obviously. It's a little hard to see why this is happening, but on what line is the error thrown, for what object?

[VBnewbeee]

I totally agree that it should work! However, it fails on If sd.Count > 0 Then
in setCachedEdit(). The error msg is System.NullReferenceException was unhandled by user code Message="Object reference not set to an instance of an object." I think at that point, sd > 0 is not true, sd is empty.

The funny thing is, when I change Dim index As String = GridView1.PageIndex + 1 in CacheData(), it cached whatever values that I assigned in the previous time I compiled. Then, I go back and changed the above statement back to original (Dim index As String = GridView1.PageIndex in CacheData()), everything is working fine after that, all values cached when paging!!! I don't know what's going on, obviously, it's driving me nuts...Any idea?

[mendhak]

When debugging, is GridView1.PageIndex = e.NewPageIndex anyways? Or are they different values before the statement is executed?

Also, this statement is somewhat worrying

The funny thing is, when I change Dim index As String = GridView1.PageIndex + 1 in CacheData(), it cached whatever values that I assigned in the previous time I compiled.

You're values from the previous compilation are remembered?

[Eclipsyo]

i think its something to do with your logic as the page event occurs...

Try adding a parameter to your sub and use the grids previous index before the event fires off.

currentGridIndex Being e.NewPageIndex? or e.index? (off of my memory)

Private Sub setCachedEdit(currentGridIndex as integer)
        
Dim sd As StringDictionary = Cache.Get("cachedRMAssignValues" & currentGridIndex)

'OR you COULD do this  to prevent the crash:
Dim sd As StringDictionary
if not Cache.Get("cachedRMAssignValues" & currentGridIndex) Is Nothing then
          sd =Cache.Get("cachedRMAssignValues" & currentGridIndex)
          If sd.Count > 0 Then .....
          ' rest of ur code
          end if
end if

End Sub


USING  setCachedEdit(e.NewPageIndex) when u call setCachedEdit().

[VBnewbeee]

Mendhak: Yes, my values from the previous compilation are remembered. I find it very odd myself. How? I don't know. That's why it's driving me nuts.

Eclipsyo: I agree that some kind of logic is off set as the page event occurs. Although I don't know why yet, your idea seems to work. Thank you very much!