Inline Mail Part URLs

inline_mail_part_urls.rb

module InlineMailPartUrls
  def url
    # I'm toggling this behaviour based on an environment variable. 
    # As far as I can see, there is no (better) way to decide whether or not
    # the url is being called from a Rails Mailer Preview vs the actual Mailer call.
    if ENV["INLINE_MAIL_PART_URLS"] == "true"
      # Encode the part body in a data URI
      # http://en.wikipedia.org/wiki/Data_URI_scheme
      "data:#{mime_type};base64,#{Base64.encode64(body.decoded)}"
    else
      # If turned off, just defer to the superclass, which generates a
      # "cid:" URI.
      super
    end
  end
end

class Mail::Part
  # use InlineMailPartUrls for all attachments
  prepend InlineMailPartUrls
end