title: Error 422 (Unprocessable Entity) while making Ajax call on Rails Controller
body: <p>Here is my code:</p>
  
  <pre><code>class EventController &lt; ApplicationController
  
    def update
      render :json =&gt; { :status =&gt; :ok, :message =&gt; 'Good Morning'}
    end
  end
  </code></pre>
  
  <p>and this is my route entry:</p>
  
  <pre><code>post 'event/update', controller:'event', action: :update
  </code></pre>
  
  <p><strong>Error Message</strong></p>
  
  <pre><code>   &lt;header&gt;
    &lt;h1&gt;
      ActionController::InvalidAuthenticityToken
        in EventController#update
    &lt;/h1&gt;
  &lt;/header&gt;
  
  &lt;div id="container"&gt;
    &lt;h2&gt;ActionController::InvalidAuthenticityToken&lt;/h2&gt;
  
  
  
  Rails.root: /Clients/M/Application/HITS
  
  Framework Trace
  actionpack (4.1.4) lib/action_controller/metal/request_forgery_protection.rb:176:in `handle_unverified_request'
  actionpack (4.1.4) lib/action_controller/metal/request_forgery_protection.rb:202:in `handle_unverified_request'
  actionpack (4.1.4) lib/action_controller/metal/request_forgery_protection.rb:197:in `verify_authenticity_token'
  activesupport (4.1.4) lib/active_support/callbacks.rb:424:in `block in make_lambda'
  activesupport (4.1.4) lib/active_support/callbacks.rb:160:in `call'
  activesupport (4.1.4) lib/active_support/callbacks.rb:160:in `block in halting'
  activesupport (4.1.4) lib/active_support/callbacks.rb:86:in `call'
  activesupport (4.1.4) lib/active_support/callbacks.rb:86:in `run_callbacks'
  actionpack (4.1.4) lib/abstract_controller/callbacks.rb:19:in `process_action'
  actionpack (4.1.4) lib/action_controller/metal/rescue.rb:29:in `process_action'
  actionpack (4.1.4) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
  activesupport (4.1.4) lib/active_support/notifications.rb:159:in `block in instrument'
  activesupport (4.1.4) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
  activesupport (4.1.4) lib/active_support/notifications.rb:159:in `instrument'
  actionpack (4.1.4) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
  actionpack (4.1.4) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
  activerecord (4.1.4) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
  actionpack (4.1.4) lib/abstract_controller/base.rb:136:in `process'
  actionview (4.1.4) lib/action_view/rendering.rb:30:in `process'
  actionpack (4.1.4) lib/action_controller/metal.rb:196:in `dispatch'
  actionpack (4.1.4) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
  actionpack (4.1.4) lib/action_controller/metal.rb:232:in `block in action'
  actionpack (4.1.4) lib/action_dispatch/routing/route_set.rb:82:in `call'
  actionpack (4.1.4) lib/action_dispatch/routing/route_set.rb:82:in `dispatch'
  actionpack (4.1.4) lib/action_dispatch/routing/route_set.rb:50:in `call'
  actionpack (4.1.4) lib/action_dispatch/journey/router.rb:71:in `block in call'
  actionpack (4.1.4) lib/action_dispatch/journey/router.rb:59:in `each'
  actionpack (4.1.4) lib/action_dispatch/journey/router.rb:59:in `call'
  actionpack (4.1.4) lib/action_dispatch/routing/route_set.rb:678:in `call'
  rack (1.5.2) lib/rack/etag.rb:23:in `call'
  rack (1.5.2) lib/rack/conditionalget.rb:35:in `call'
  rack (1.5.2) lib/rack/head.rb:11:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/flash.rb:254:in `call'
  rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context'
  rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/cookies.rb:560:in `call'
  activerecord (4.1.4) lib/active_record/query_cache.rb:36:in `call'
  activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:621:in `call'
  activerecord (4.1.4) lib/active_record/migration.rb:380:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
  activesupport (4.1.4) lib/active_support/callbacks.rb:82:in `run_callbacks'
  actionpack (4.1.4) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/reloader.rb:73:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
  railties (4.1.4) lib/rails/rack/logger.rb:38:in `call_app'
  railties (4.1.4) lib/rails/rack/logger.rb:20:in `block in call'
  activesupport (4.1.4) lib/active_support/tagged_logging.rb:68:in `block in tagged'
  activesupport (4.1.4) lib/active_support/tagged_logging.rb:26:in `tagged'
  activesupport (4.1.4) lib/active_support/tagged_logging.rb:68:in `tagged'
  railties (4.1.4) lib/rails/rack/logger.rb:20:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/request_id.rb:21:in `call'
  rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
  rack (1.5.2) lib/rack/runtime.rb:17:in `call'
  activesupport (4.1.4) lib/active_support/cache/strategy/local_cache_middleware.rb:26:in `call'
  rack (1.5.2) lib/rack/lock.rb:17:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/static.rb:64:in `call'
  rack (1.5.2) lib/rack/sendfile.rb:112:in `call'
  railties (4.1.4) lib/rails/engine.rb:514:in `call'
  railties (4.1.4) lib/rails/application.rb:144:in `call'
  rack (1.5.2) lib/rack/lock.rb:17:in `call'
  rack (1.5.2) lib/rack/content_length.rb:14:in `call'
  rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service'
  /Users/JD/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:138:in `service'
  /Users/JD/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:94:in `run'
  /Users/JD/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/server.rb:295:in `block in start_thread'
  
  Full Trace
  actionpack (4.1.4) lib/action_controller/metal/request_forgery_protection.rb:176:in `handle_unverified_request'
  actionpack (4.1.4) lib/action_controller/metal/request_forgery_protection.rb:202:in `handle_unverified_request'
  actionpack (4.1.4) lib/action_controller/metal/request_forgery_protection.rb:197:in `verify_authenticity_token'
  activesupport (4.1.4) lib/active_support/callbacks.rb:424:in `block in make_lambda'
  activesupport (4.1.4) lib/active_support/callbacks.rb:160:in `call'
  activesupport (4.1.4) lib/active_support/callbacks.rb:160:in `block in halting'
  activesupport (4.1.4) lib/active_support/callbacks.rb:86:in `call'
  activesupport (4.1.4) lib/active_support/callbacks.rb:86:in `run_callbacks'
  actionpack (4.1.4) lib/abstract_controller/callbacks.rb:19:in `process_action'
  actionpack (4.1.4) lib/action_controller/metal/rescue.rb:29:in `process_action'
  actionpack (4.1.4) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
  activesupport (4.1.4) lib/active_support/notifications.rb:159:in `block in instrument'
  activesupport (4.1.4) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
  activesupport (4.1.4) lib/active_support/notifications.rb:159:in `instrument'
  actionpack (4.1.4) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
  actionpack (4.1.4) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
  activerecord (4.1.4) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
  actionpack (4.1.4) lib/abstract_controller/base.rb:136:in `process'
  actionview (4.1.4) lib/action_view/rendering.rb:30:in `process'
  actionpack (4.1.4) lib/action_controller/metal.rb:196:in `dispatch'
  actionpack (4.1.4) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
  actionpack (4.1.4) lib/action_controller/metal.rb:232:in `block in action'
  actionpack (4.1.4) lib/action_dispatch/routing/route_set.rb:82:in `call'
  actionpack (4.1.4) lib/action_dispatch/routing/route_set.rb:82:in `dispatch'
  actionpack (4.1.4) lib/action_dispatch/routing/route_set.rb:50:in `call'
  actionpack (4.1.4) lib/action_dispatch/journey/router.rb:71:in `block in call'
  actionpack (4.1.4) lib/action_dispatch/journey/router.rb:59:in `each'
  actionpack (4.1.4) lib/action_dispatch/journey/router.rb:59:in `call'
  actionpack (4.1.4) lib/action_dispatch/routing/route_set.rb:678:in `call'
  rack (1.5.2) lib/rack/etag.rb:23:in `call'
  rack (1.5.2) lib/rack/conditionalget.rb:35:in `call'
  rack (1.5.2) lib/rack/head.rb:11:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/flash.rb:254:in `call'
  rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context'
  rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/cookies.rb:560:in `call'
  activerecord (4.1.4) lib/active_record/query_cache.rb:36:in `call'
  activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:621:in `call'
  activerecord (4.1.4) lib/active_record/migration.rb:380:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
  activesupport (4.1.4) lib/active_support/callbacks.rb:82:in `run_callbacks'
  actionpack (4.1.4) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/reloader.rb:73:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
  railties (4.1.4) lib/rails/rack/logger.rb:38:in `call_app'
  railties (4.1.4) lib/rails/rack/logger.rb:20:in `block in call'
  activesupport (4.1.4) lib/active_support/tagged_logging.rb:68:in `block in tagged'
  activesupport (4.1.4) lib/active_support/tagged_logging.rb:26:in `tagged'
  activesupport (4.1.4) lib/active_support/tagged_logging.rb:68:in `tagged'
  railties (4.1.4) lib/rails/rack/logger.rb:20:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/request_id.rb:21:in `call'
  rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
  rack (1.5.2) lib/rack/runtime.rb:17:in `call'
  activesupport (4.1.4) lib/active_support/cache/strategy/local_cache_middleware.rb:26:in `call'
  rack (1.5.2) lib/rack/lock.rb:17:in `call'
  actionpack (4.1.4) lib/action_dispatch/middleware/static.rb:64:in `call'
  rack (1.5.2) lib/rack/sendfile.rb:112:in `call'
  railties (4.1.4) lib/rails/engine.rb:514:in `call'
  railties (4.1.4) lib/rails/application.rb:144:in `call'
  rack (1.5.2) lib/rack/lock.rb:17:in `call'
  rack (1.5.2) lib/rack/content_length.rb:14:in `call'
  rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service'
  /Users/JD/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:138:in `service'
  /Users/JD/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:94:in `run'
  /Users/JD/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/server.rb:295:in `block in start_thread'
  
  
  
  Request parameters
  {"name"=&gt;"John",
   "time"=&gt;"2pm"}
  
  Session dump
  _csrf_token: "a4y1SDHaXHRkiyIW8AncOYcPgRiO5syFXihKc5qqZlg="
  session_id: "0d860d9a22ba027b92fcfa2ec5055965"
  
  Env dump
  GATEWAY_INTERFACE: "CGI/1.1"
  HTTP_ACCEPT: "*/*"
  HTTP_ACCEPT_ENCODING: "gzip,deflate"
  HTTP_ACCEPT_LANGUAGE: "en-US,en;q=0.8,ur;q=0.6"
  HTTP_CACHE_CONTROL: "no-cache"
  HTTP_PRAGMA: "no-cache"
  REMOTE_ADDR: "127.0.0.1"
  REMOTE_HOST: "127.0.0.1"
  SERVER_NAME: "0.0.0.0"
  SERVER_PROTOCOL: "HTTP/1.1"
  
  Response headers
  None
  
  &lt;/div&gt;
  </code></pre>