You’re most likely going to deal with file uploads within your Rails application.  If you haven’t yet, it’s coming and hopefully this will save you some time.  I spent about an hour today racking my brain as to why I couldn’t validate different image types: image/jpeg, image/gif, and image/png.  I was doing a simple string check that looked like this:

def check_format
content_type = params[:photo].content_type
if content_type != “image/pjpeg” && content_type != “image/jpeg” && content_type != “image/gif” && content_type != “image/png”
“Error: You’ve specified the wrong file type”
end
end

This was failing repeatedly and even printing the content_type variable would yield image/jpeg.  It seemed that everything should work perfectly.  The only thing I could fathom is that there may be some extraneous garbage at the end of the string.  After doing a nice ruby chomp this solved the problem:

content_type = params[:photo].content_type.chomp

I hope this saves you some frustration in the future.