[RESOLVED] keep user input available through gridview paging

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.

Code:

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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

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Here's my GridView Paging:

Code:

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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

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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?

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?

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

Also, this statement is somewhat worrying

Quote:

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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.

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You're values from the previous compilation are remembered?

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.

Code:

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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().

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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!