class BookInfo(models.Model):   #创建书本信息类，继承models.Model

    booktitle=models.CharField(max_length=20)

    bookdata=models.DateField()

    def __unicode__(self):

        return self.booktitle

class HeroInfo(models.Model):   #创建英雄信息类
    heroname=models.CharField(max_length=10)
    herosex=models.CharField(max_length=1)
    herocontent=models.CharField(max_length=50)
    herobook=models.ForeignKey('BookInfo',on_delete=models.CASCADE,)   #引用外键，即BookInfo对象
    def __unicode__(self):
        return self.heroname