Code demonstrating multi-value params working and not working with Rack

0-readme.md

Readme

Code to accompany the weblog posting: Ruby/Rack and Multiple Value Request Param Pain — Part One

Demonstrating multi-value params not working with out-of-the-box Rack, but working with a monkey patched Rack.

1-only-ever-one.rb

#!/usr/bin/env ruby

# For an explanation, see my post at http://xampl.com/so/2009/12/16/rubyrack-and-multiple-value-request-param-pain-—-part-one/

require 'rubygems'
require 'haml'
require 'sinatra'

get '/' do
  haml :play, :layout => false
end

post '/' do
  puts "#{File.basename(__FILE__)}:#{__LINE__} #{ __method__ } params: #{ params.inspect }"
  haml :play, :layout => false
end

use_in_file_templates!

__END__

@@ play
%html
  %head
    %title play
  %body
    %h1 Play
    %form{ :method => 'post' }
      %select{ :id => 'several', :name => 'several', :size => 4, :multiple => 'multiple' }
        %option{ :id => 'one' } one
        %option{ :id => 'two' } two
        %option{ :id => 'three' } three
        %option{ :id => 'four' } four
      %input{ :type => 'submit' }

2-multiple.rb

#!/usr/bin/env ruby

# For an explanation, see my post at http://xampl.com/so/2009/12/16/rubyrack-and-multiple-value-request-param-pain-—-part-one/

require 'rubygems'
require 'haml'
require 'sinatra'

require 'rack-monkey-patch'

get '/' do
  haml :play, :layout => false
end

post '/' do
  puts "#{File.basename(__FILE__)}:#{__LINE__} #{ __method__ } params: #{ params.inspect }"
  haml :play, :layout => false
end

use_in_file_templates!

__END__

@@ play
%html
  %head
    %title play
  %body
    %h1 Play
    %form{ :method => 'post' }
      %select{ :id => 'several', :name => 'several', :size => 4, :multiple => 'multiple' }
        %option{ :id => 'one' } one
        %option{ :id => 'two' } two
        %option{ :id => 'three' } three
        %option{ :id => 'four' } four
      %input{ :type => 'submit' }

3-rack-monkey-patch.rb

# For an explanation, see my post at http://xampl.com/so/2009/12/16/rubyrack-and-multiple-value-request-param-pain-—-part-one/

require 'rack'

module Rack
  module Utils

    def normalize_params(params, name, v = nil)
      name =~ %r(\A[\[\]]*([^\[\]]+)\]*)
      k = $1 || ''
      after = $' || ''

      return if k.empty?

      if after == ""
        # The original simply did: params[k] = v
        case params[k]
          when Array
            params[k] << v
          when String
            params[k] = [ params[k], v ]
          else
            params[k] = v
        end
      elsif after == "[]"
        params[k] ||= []
        raise TypeError, "expected Array (got #{params[k].class.name}) for param `#{k}'" unless params[k].is_a?(Array)
        params[k] << v
      elsif after =~ %r(^\[\]\[([^\[\]]+)\]$) || after =~ %r(^\[\](.+)$)
        child_key = $1
        params[k] ||= []
        raise TypeError, "expected Array (got #{params[k].class.name}) for param `#{k}'" unless params[k].is_a?(Array)
        if params[k].last.is_a?(Hash) && !params[k].last.key?(child_key)
          normalize_params(params[k].last, child_key, v)
        else
          params[k] << normalize_params({}, child_key, v)
        end
      else
        params[k] ||= {}
        raise TypeError, "expected Hash (got #{params[k].class.name}) for param `#{k}'" unless params[k].is_a?(Hash)
        params[k] = normalize_params(params[k], after, v)
      end

      return params
    end

    module_function :normalize_params

  end
end