Use the following code
<s:if test="#attr.row.Commentaire != null && #attr.row.Commentaire != ''">
The if
tag uses the test
attribute to evaluate OGNL expression to a boolean value.
You may also want to use an a
tag which renders a HTML anchor tag that could be used combined with the if
tag to
consult the contents of the property
There's also a debug
tag that could be used to wrap other tags to show you a link that will render a debug data.
<s:debug>
<s:property value="%{#attr.row.Commentaire}"/>
</s:debug>