After reading the topic page action in seam reference. I wonder if I could do and if it is a good practice of doing a check whether a user is log in or not then perform a redirect if necessary.

I don't fully understand this piece of code.

<s:button view="/#{empty userFrom ? 'UserList' : userFrom}.xhtml"
id="done"
value="Done"/>

I got this code from xhtml file generate from seam gen' seam generate-entities command. the userFrom is a parameter variable from page.xml file. when the userFrom is empty it will be evaluated to UserList.xhtml but if userFrom is not empty it will be evaluated to .xhtml? If it happens that the userFrom has a value this will produce an error right? Can I assume that userFrom will never have a value?

Thanks