fix mongo mapper's as_json so it handles :include with sub-options (e.g. :include => {:foos => {:only => "name"}} )

mongomapper_json.rb

module App
  class Model
    def as_json(opts={})
      hash = super
      if opts && inclusions = opts[:include]
        case inclusions
        when Array
          inclusions.each do |key|
            hash[key.to_s] = send(key.to_sym).as_json
          end
        when Hash
          inclusions.each do |key, sub_opts|
            hash[key.to_s] = send(key.to_sym).as_json.map {|r| r.as_json(sub_opts) }
          end
        when String, Symbol
          hash[inclusions.to_s] = send(inclusions.to_sym).as_json.map(&:as_json)
        end
      end
      hash
    end
  end
end