gistfile1.rb

# Splits a given parameter hash into two hashes - one containing all
      # string and non-binary parameters, and one containing all file/binary parameters.
      # This action is performed recursively so that:
      #   params = {:user=>{:attributes=>{:file=>some_file, :name=>"user name"}}, :foo=>"bar"}
      #   normal, multipart = split_multipart_params(params)
      #   normal.inspect # => {:user=>{:attributes=>{:name=>"user name"}}, :foo=>"bar"}
      #   multipart.inspect # => {:user=>{:attributes=>{:file=>some_file}}}
      def split_multipart_params(params, *hash_path)
        strings = {}
        files = {}
        params.each do |key, value|
          if value.is_a?(Hash)
            # Call recursively
            s, f = split_multipart_params(value, *(hash_path+[key]))
            strings = strings.deep_merge(s)
            files = files.deep_merge(f)
          else 
            # Insert it into files at the current key path if it is a binary,
            # and into strings if it is not.
            pwd = (value.is_a?(IO))? files : strings
            hash_path.each do |component|
              pwd[component] ||= {}
              pwd = pwd[component]
            end
            pwd[key] = value
          end
        end
        return strings, files
      end