Blind Squirrel

Once in a while, even a blind squirrel finds a nut.

Different Content in Rails Based on UserAgent

I was recently working on a website built using Rails that needed to render different content for certain user agents. Specifically, we needed simpler versions of certain pages for BlackBerry devices. Here’s how I accomplished it.

First, I added a new mime-type for BlackBerry by adding the following line to config/initializers/mime_types.rb:

mime_types.rb 
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Mime::Type.register_alias "text/html", :blackberry

Next, I added two utility methods to app/controllers/application.rb:

application.rb 
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# Checks UserAgent
def is_blackberry?
  ua = request.user_agent
  return false if ua.nil?
  return false if ! ua.downcase.index('blackberry')

  # Don't call the BlackBerry 9800 a BlackBerry, since it has a modern browser
  # based on WebKit:
  # Mozilla/5.0 (BlackBerry; U; BlackBerry 9800; en) AppleWebKit/534.1+ (KHTML, Like Gecko) Version/6.0.0.141 Mobile Safari/534.1+
  return false if ua.downcase.index('webkit')

  # Must be a BlackBerry!
  true
end

# Sets the respond_to format to blackberry if blackberry
def set_blackberry_format
  if !request.xhr? && is_blackberry?
    request.format = :blackberry
  end
end

With that in hand, it’s easy to render BlackBerry specific content on specific pages:

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set_blackberry_format
respond_to do |format|
  format.blackberry
  format.html
  format.js { render :layout => false }
end