call swf from datagrid

[stonyx]

hi coders, how can i call SWFLoader only if there is a swf in the XML
my XML sometimes has <desc> as description (only text)
and sometimes <video> could be swf or flv
everything is ok if all the <book> tags have a <video> tag but if there is no <video> it will throw an error

<catalog>
<book>
<name></name>
<desc></desc>
</book>
<book>
<name></name>
<video></video>
</book>
</catalog>

<mx: DataGrid dataProvider="{xlc}"
width="161" id="datagrid" scroll="true" height="531" x="5" showScrollTips="true" variableRowHeight="true" y="4" >

<mx:SWFLoader x="10" y="118" width="546" height="294.5"
source="{datagrid.selectedItem.video.*}"/>

<mx:TextArea id="areaDeTexto" width="560" height="414" htmlText="{datagrid.selectedItem.desc}" x="3" y="3"/>

help

[Tink]

<mx: DataGrid dataProvider="{xlc}"
width="161" id="datagrid" scroll="true" height="531" x="5" showScrollTips="true" variableRowHeight="true" y="4" change=onDataGridChange( event );>

<mx:SWFLoader id="myLoader" x="10" y="118" width="546" height="294.5" >

then in AS

private function onDataGridChange( event:Event ):void
{
if( datagrid.selectedItem.video ) myLoader.source = datagrid.selectedItem.video;
}

[stonyx]

Gracias Tink