The change you wanted was rejected.Maybe you tried to change something you didn’t have access to.
422 Unprocessable Entity (WebDAV) (RFC 4918)
The request was well-formed but was unable to be followed due to semantic errors.
在rails应用中出现这个422错误基本上是由于 `authenticity token` 造成的.在提交表单的时候如果不想手动拼加上`authenticity token`可以这样：
protect_from_forgery :except => :some_action