I've got a case for my model where the name field is required, ONLY if
the comment field has been filled out. I thought I could do this like
validates_presence_of :name, :unless=>@comment.nil?
but I can't seem to get the syntax right, can somebody help me out? I'm
not sure how the incoming data has been provided to the model, so that I
can reference the value of what is going to be the comment field, if
that makes sense.