Django rest serializer.data是一个空的OrderedDict（）

Here is my model:

这是我的模型:

from django.db import models
from django.contrib.auth.models import User
from datetime import datetime


class Staff(models.Model):
    employer = models.ForeignKey("shops.Shop")
    user = models.ForeignKey(User)

    def __unicode__(self):
        return self.user.username
from django.db im