Is there an expression to know if a feature has attachments? To show or hide the image caption.

Hi, 

I'm using the feature attachments control in a GeoCortex report, and a separate label underneath to display a caption with the image. 

I'd like to show this label only when the feature has attachments - the label is populated in all cases, but will be listed elsewhere in the report if there are no image attachments. 

Is there any expression on the feature, or property the attachment controls that I can use to then show or hide this label control? Something like  a singleFeatureattachment.hasAttachments  property?

Thanks!

Andrew