[Solved] Dynamically generating RadGrid on user action

[cheburek]

I have dynamically generated user control that contains RadGrid.

Protected Overrides Sub CreateChildControls()
      MyBase.CreateChildControls()
      GenerateTable()
    End Sub

    Private Sub GenerateTable()
      If BtnExpandOpen Then
        Dim ctrl = GetProperControl(RowIndex)
        If ctrl IsNot Nothing Then
          ctrl.WriteToDisplay(Me)
          PanelCategory.Controls.Add(ctrl)
        End If
      End If
    End Sub

    Private Sub btnExpand_Click(ByVal sender As Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles btnExpand.Click
      BtnExpandOpen = Not BtnExpandOpen
      SetExpandButtonState()

      GenerateTable()
    End Sub

This control I need to show up due to user request (some button click). When user clicks on button control is rendered properly but if I try to change page then grid is not changing its state.
If i try to change the page size then it throws exception like that:

[NullReferenceException: Object reference not set to an instance of an object.]
   Telerik.Web.UI.RadGrid.RaisePostBackEvent(String eventArgument) +8609
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +175

What have I do if I need to create RagGrid not in PageInit or PageLoad events but rendered grid must have some postbacks (i.e. paging)?
Thank you

[cheburek]

If you try creating your controls in the CreateChildControls you have to get the old value somehow.
The typical solution is to store this value in a property backed in the ViewState.

    Protected Overrides Sub LoadViewState(ByVal savedState As Object)
      MyBase.LoadViewState(TryCast(savedState, Pair).First)
      EnsureChildControls()
    End Sub

    Protected Overrides Function SaveViewState() As Object
      Return New Pair(MyBase.SaveViewState(), Nothing)
    End Function

[Iana Tsolova]

Hi cheburek,

Note that if grid is created entirely i code behind, it should be created on Page_Init as described here.
I suggest that you check out this article as see how grid structure could be changed dynamically on Page_Init.

Give it a try and let me know how it goes.

All the best,
Iana
the Telerik team

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