gistfile1.rb

module NestedParams
  NESTED_PARAM_PREFIX = /^__nested_/i

  module ControllerClassMethods
    def expand_nested_params
      before_filter :handle_params #{ |c| c.expand_nested_params(c.params) }
    end
  end
  
  module ControllerInstanceMethods
    def handle_params
      self.params.replace(expand_nested_params(params))
      if @seen_exp_params
        logger.info "Expanded params"
      end
      true
    end
    
    def expand_nested_params(h)
      h.each_pair do | k, v |
        if k =~ NESTED_PARAM_PREFIX
          @seen_exp_params = true
          expanded_key = k.gsub(NESTED_PARAM_PREFIX, '')
          expanded = CGIMethods.parse_query_parameters(v)
          # Special case - the hash with one value which is an array must be expanded
          # in an array neglecting the subkey
          if expanded.is_a?(Hash) && (expanded.length == 1) && expanded[expanded.keys.first].is_a?(Array)
            h[expanded_key]  = expanded.values.pop
            h[expanded_key] = [] if h[expanded_key].empty?
          elsif expanded == {}
            h[expanded_key] = []
          else
            h[expanded_key] = expanded
          end
          
          h.delete(k)
        elsif v.is_a?(Hash)
          expand_nested_params(v)
        end
      end
      return h
    end
  end
  
  ActionController::Base.send :include, ControllerInstanceMethods
  ActionController::Base.send :extend, ControllerClassMethods

end