Advanced via NeedDataSource

The key to the advanced data binding of a RadPivotGrid control is handling the NeedDataSource event. RadPivotGrid fires the NeedDataSource event each time it needs to be bound to a data source. If, at the time of the event, the DataSource property is not set to a valid data source object, the pivot grid will not behave correctly.

This event fires in the following cases:

• Right after OnLoad, Telerik RadTreeList checks the ViewState for stored TreeList-related information. If such information is missing (when the page loads for the first time), the NeedDataSource event is fired. This also means that if the EnableViewState property of the control has been set to false, the treelist will bind each time the page loads (not only the first time).

• When a paging operation occurs.

• When a sorting operation occurs.

• After expand/collapse.

• When other operations requiring Rebind occurs.

The advantage of using the NeedDataSource event is that you have the flexibility of generating your data source in the code-behind, but are freed from handling the logic of when and how data-binding should take place.It is still your responsibility to properly construct a data source object and assign it to the pivotgrid's DataSource property.

Important: You should never call the Rebind () method in a NeedDataSource event handler.You should never call DataBind () as well when using advanced data-binding through NeedDataSource .

RadPivotGrid does not fire the NeedDataSource event unless it is visible(Visible=True).

In a NeedDataSource event handler, you should prepare the data source(list of objects) for RadPivotGrid and assign it to the pivotgrid's DataSource property:

protected void RadPivotGrid1_NeedDataSource(object sender, PivotGridNeedDataSourceEventArgs e)
{
    RadPivotGrid1.DataSource = GetDataTable("SELECT * FROM Transportation");
}

public DataTable GetDataTable(string query)
{
    String ConnString = ConfigurationManager.ConnectionStrings["TelerikConnectionString"].ConnectionString;
    SqlConnection conn = new SqlConnection(ConnString);
    SqlDataAdapter adapter = new SqlDataAdapter();
    adapter.SelectCommand = new SqlCommand(query, conn);

    DataTable myDataTable = new DataTable();

    conn.Open();
    try
    {
        adapter.Fill(myDataTable);
    }
    finally
    {
        conn.Close();
    }

    return myDataTable;
}

Protected Sub RadPivotGrid1_NeedDataSource(sender As Object, e As PivotGridNeedDataSourceEventArgs)
    RadPivotGrid1.DataSource = GetDataTable("SELECT * FROM Transportation")
End Sub

Public Function GetDataTable(query As String) As DataTable
    Dim ConnString As [String] = ConfigurationManager.ConnectionStrings("TelerikConnectionString").ConnectionString
    Dim conn As New SqlConnection(ConnString)
    Dim adapter As New SqlDataAdapter()
    adapter.SelectCommand = New SqlCommand(query, conn)

    Dim myDataTable As New DataTable()

    conn.Open()
    Try
        adapter.Fill(myDataTable)
    Finally
        conn.Close()
    End Try

    Return myDataTable
End Function