Show Document Name

Hi
My scenario is that I am using the Upload Widget to upload documents .
Now the Document type is Single. Only 1 document needs to be Uploaded.

Now I am showing the Document in the next task.
Here, I am using the Link widget to download the Document.

For a single Document type , I have a JavaScript variable and I return the value as
return "/bonita/portal/" + $data.context.attachedDoc_ref.url;

In the link Widget , I set the url as the JavaScript variable.
This works fine. I am able to download the Document.
But I need to Show the FileName of the Document.
But in the Text section i have tried using {{attachedDoc_ref.fileName}} and {{context.attachedDoc_ref.fileName}} .
But this does not show the document name.

Kindly suggest