# NeedDataSource Event

Fired when RadGrid needs a data source for rebinding.

### Event Parameters

* `(object)` **sender**

  * The control that fires the event

* `(GridNeedDataSourceEventArgs)` **e**

  * Event arguments

    * `(boolean)` **e.IsFromDetailTable**

      Returns true if the event is fired for the DetailTable.

    * `(GridRebindReason)` **e.RebindReason**

      Gets a value specifying why the event was fired.

    * `(int)` **e.RowsCount**

      Gets a value specifying the number of rows that should be extracted from the data source when virtualization and custom paging are enabled.

    * `(int)` **e.StartRowIndex**

      Gets a value specifying the index of the first row in the data source that should be extracted when virtualization and custom paging are enabled.

## Attaching the event

In the Markup

```ASP.NET
<telerik:RadGrid ID="RadGrid1" runat="server" OnNeedDataSource="RadGrid1_NeedDataSource">
</telerik:RadGrid>
```

In the Code behind

```C#
protected void Page_Init(object sender, EventArgs e)
{
    RadGrid1.NeedDataSource += RadGrid1_NeedDataSource;
}
```

```VB
Protected Sub Page_Init(sender As Object, e As EventArgs) Handles Me.Init
    AddHandler RadGrid1.NeedDataSource, AddressOf RadGrid1_NeedDataSource
End Sub
```

The event handler

```C#
protected void RadGrid1_NeedDataSource(object sender, GridNeedDataSourceEventArgs e)
{
    bool isFromDetailTable = e.IsFromDetailTable;
    GridRebindReason rebindReason= e.RebindReason;
    int rowsCount = e.RowsCount;
    int startRowIndex = e.StartRowIndex;
}
```

```VB
Protected Sub RadGrid1_NeedDataSource(ByVal sender As Object, ByVal e As GridNeedDataSourceEventArgs)
    Dim isFromDetailTable As Boolean = e.IsFromDetailTable
    Dim rebindReason As GridRebindReason = e.RebindReason
    Dim rowsCount As Integer = e.RowsCount
    Dim startRowIndex As Integer = e.StartRowIndex
End Sub
```

## See Also

* [Telerik RadGrid Event Sequence](https://www.telerik.com/products/aspnet-ajax/documentation/controls/grid/control-lifecycle/event-sequence)