I want to display the results of a pivot table in a datagrid. I have defined the static columns in the <Columns> section as bound columns. Since I don't know what the pivoted columns are going to be (they are data dependent) I have to dynamically add them in the code before doing the data binding. That works ok, but on postback is where it gets ugly. What I have to do in the Page_Init is recreate the dynamic columns because they won't be preserved in the postback. Unless they are recreated in the Page_Init event, the sort event will not fire when the header of one of the "pivot" (i.e. dynamic) columns is clicked. This means I have to save those column names in a Session variable, so I know what I need to recreate on the postback. That handles the problem with sorting on a pivot column. If instead of doing a sort, the user changes any of the criteria, I get the new set of data and I transform it into a new pivot table. Now I have to delete all of the pivot columns in the datagrid from the previous request. It seems that there are a whole lot of issues to deal with for dynamically-created columns. Is there an easier way? Am I missing something here? Thanks.
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Shouldn't be a problem. My datagrid does something similar and all I do is re-build columns in the viewstate event like so:
I use a property to maintain a bool value of whether the columns have been added:
Private Property DynamicColumnAdded() As Boolean
Get
If ViewState("ColumnAdded") Is Nothing Then
Return False
Else
Return True
End If
End Get
Set(ByVal Value As Boolean)
ViewState("ColumnAdded") = Value
End Set
End Property
Then in viewstate event:
Protected Overrides Sub LoadViewState(ByVal savedState As Object) MyBase.LoadViewState(saved
If Me.DynamicColumnAdded Then
Me.CreateTemps()
End If
End Sub
After I create the columns I set: DynamicColumnAdded = True
Also, I clear the columns like so before building template columns: Datagrid1.Columns.Clear()
regards,
KS
How do you know the names of the dynamic columns that you have to re-create in your CreateTemps(). Are you saving the names of the dynamic columns somewhere? Are you putting them in a Session variable maybe or using the SaveViewState()? Mine vary because of the nature of the pivot table. If the postback is due to a SortCommand, then I have to know the name of the columns so that I can recreate it in the grid in order for the SortCommand Event handler to fire.
i too had the same problem
In Page_Load Event changed from
If Not Page.IsPostBack Then
BindGrid()
End If
to
BindGrid()
in BindGrid()
while adding new bound columns check
If dgResults.Columns.Count = 0 Then
dgResults.AutoGenerateColu
dgResults.AllowSorting = True
dgResults.Width.Percentage
For loopCount = 0 To columnsList.Count - 1
resultGridColumn = New BoundColumn
resultGridColumn.DataField
resultGridColumn.HeaderTex
resultGridColumn.SortExpre
dgResults.Columns.Add(resu
Next
End If
this sorted out the problem
sort event was fired after this
the column list was dynamic and so were based on xml - for each xml node id it was different columns and different tables
i didnt maintain in the viewstate, as the column were based on xml and xml id
and i call the bind grid in page load, its generated again, obvious the column list is not going to change during sort event.
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by: b1xml2Posted on 2005-06-06 at 07:50:37ID: 14153685
can you instead change the underlying source, and set AutoGenerateColumns to true and hook into the ItemCreated and ItemDataBound to further finetune the display. What I mean by this is you have your original source of data which you transform by code to another dataset with the columns in the datatable determined by the original data, thereby having a datatable that can be plugged straight into a DataGrid. This way, you deal purely with the data and let the DataGrid do its thing.