user模型扩展字段无法写入数据

![image](https://user-images.githubusercontent.com/12623898/60066388-8ca40400-9739-11e9-844c-d93ffc25222a.png)
![image](https://user-images.githubusercontent.com/12623898/60066414-aa716900-9739-11e9-954a-5a7749861354.png)
![image](https://user-images.githubusercontent.com/12623898/60066442-c96ffb00-9739-11e9-9f36-b2d3c5fbe4b5.png)
