verify_authenticity_token

Rails2.1にバージョンアップしてソースをいろいろ書き換えているが
今度は、下記のような例外が発生してしまう。

ActionController::InvalidAuthenticityToken (ActionController::InvalidAuthenticityToken):
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/request_forgery_protection.rb:86:in `verify_authenticity_token'
    /Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/callbacks.rb:173:in `send'
    /Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/callbacks.rb:173:in `evaluate_method'
    /Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/callbacks.rb:161:in `call'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/filters.rb:430:in `call'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/filters.rb:592:in `run_before_filters'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/filters.rb:578:in `call_filters'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/filters.rb:573:in `perform_action_without_benchmark'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/benchmark.rb:293:in `measure'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/rescue.rb:201:in `perform_action_without_caching'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/caching/sql_cache.rb:13:in `perform_action'
    /Library/Ruby/Gems/1.8/gems/activerecord-2.1.0/lib/active_record/connection_adapters/abstract/query_cache.rb:33:in `cache'
    /Library/Ruby/Gems/1.8/gems/activerecord-2.1.0/lib/active_record/query_cache.rb:8:in `cache'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/caching/sql_cache.rb:12:in `perform_action'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/base.rb:529:in `send'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/base.rb:529:in `process_without_filters'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/filters.rb:569:in `process_without_session_management_support'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/session_management.rb:130:in `process'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/base.rb:389:in `process'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/dispatcher.rb:149:in `handle_request'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/dispatcher.rb:107:in `dispatch'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/dispatcher.rb:104:in `synchronize'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/dispatcher.rb:104:in `dispatch'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/dispatcher.rb:120:in `dispatch_cgi'
    /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/dispatcher.rb:35:in `dispatch'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/bin/../lib/mongrel/rails.rb:76:in `process'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/bin/../lib/mongrel/rails.rb:74:in `synchronize'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/bin/../lib/mongrel/rails.rb:74:in `process'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel.rb:159:in `process_client'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel.rb:158:in `each'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel.rb:158:in `process_client'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel.rb:285:in `run'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel.rb:285:in `initialize'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel.rb:285:in `new'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel.rb:285:in `run'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel.rb:268:in `initialize'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel.rb:268:in `new'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel.rb:268:in `run'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel/configurator.rb:282:in `run'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel/configurator.rb:281:in `each'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel/configurator.rb:281:in `run'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/bin/mongrel_rails:128:in `run'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/lib/mongrel/command.rb:212:in `run'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.4/bin/mongrel_rails:281
    /Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:502:in `load'
    /Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:502:in `load'
    /Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:354:in `new_constants_in'
    /Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:502:in `load'
    /Library/Ruby/Gems/1.8/gems/rails-2.1.0/lib/commands/servers/mongrel.rb:64
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `require'
    /Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:509:in `require'
    /Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:354:in `new_constants_in'
    /Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:509:in `require'
    /Library/Ruby/Gems/1.8/gems/rails-2.1.0/lib/commands/server.rb:39
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `require'
    ./script/server:3
    -e:2:in `load'
    -e:2


これは下記のようにAjaxのリクエストでPOSTしているのがダメらしい。

new Ajax.Request(url,
	{
		method : 'post', 
		parameters : params ,
		onComplete : showMindmap
	}) ;


Rails 2 では CSRF対策の仕組みが入っていてこうなるらしい。
取りあえず、ここも書き換えか。