paperclip + gravatar

I've found this tutorial (http://www.coffeepowered.net/2009/02/15/graceful-degredation-using-gravatar-as-a-fallback-开发者_如何学Goavatar-with-paperclip/) about implementing gravatar as default image to the paperclip-enabled model, but on implementing i see message "undefined method `match' for [:format, :png]:Array". Whats wrong in this article?

I've updated the code to make it easier for you to understand and debug.

Paperclip.interpolates(:gravatar_url) do |attachment, style|
  size = nil
  # style should be :tiny, :small, or :regular
  # size_data is assumed to be "16x16#", "20x20#", or "25x25#", i.e., a string
  size_data = attachment.styles[style][:geometry]
  if size_data
    # get the width of the attachment in pixels
    if thumb_size = size_data.match(/\d+/).to_a.first
      size = thumb_size.to_i
    end
  end
  # obtain the url from the model
  # replace nil with "identicon", "monsterid", or "wavatar" as desired
  # personally I would reorder the parameters so that size is first
  # and default is second
  attachment.instance.gravatar_url(nil, size)
end

Note I got the following error when attempting this solution:

NoMethodError: undefined method `first' for #<Hash:0xb6476178>
    from /home/bob/dev/Firehoze/app/models/user.rb:114:in `gravatar_url'

I solved it by replacing the line:

size_data = attachment.styles[style].first

with

size_data = attachment.styles[style][:geometry]

Paperclip.interpolates :gravatar_url do |attachment, style|
    attachment.instance.gravatar_url(attachment.styles[style][:geometry].split('x').first)
end

If you continue to have trouble, you could try the Avatar gem, which supports a chain of different Avatar methods, including both Paperclip and Gravatar.

NB: this is a bit of a shameless plug, since I wrote the thing.