ajax – Ember.js with rails on rails application：406注册时

当我启动对POST /users.json路由的ajax调用时,我得到406 Not Acceptable.

这是我的ajax电话：

urlBase : '/users'

signup : (username,email,password,passwordConfirmation) ->
  $.ajax
    url: "#{@.get('urlBase')}.json"
    type: "POST"
    dataType: "json"
    data:
      "user[username]": username
      "user[email]": email
      "user[password]": password
      "user[password_confirmation]": passwordConfirmation

    success: (data) ->
      alert('Completed sign up process: '+ JSON.stringify(data));
      @errorMsg = "Signed up successfully." 

    error: (jqXHR,textStatus,errorThrown) ->
      alert "Error completing sign up: " + textStatus + " error: " + errorThrown

这是日志：

Started POST "/users.json" for 127.0.0.1 at 2013-01-14 14:38:57 +0100
Processing by Devise::RegistrationsController#create as JSON
  Parameters: {"user"=>{"username"=>"obo","email"=>"obo@obo.dv","password"=>"[FILTERED]","password_confirmation"=>"[FILTERED]"}}
   (1.3ms)  begin transaction
  User Exists (1.3ms)  SELECT 1 AS one FROM "users" WHERE "users"."email" = 'obo@obo.dv' LIMIT 1
   (0.1ms)  rollback transaction
Completed 406 Not Acceptable in 311ms (ActiveRecord: 2.6ms)

我不明白为什么会这样.