数据模型类的写法

from django.db import models

# Create your models here.
class BookInfo(models.Model):
    btitle = models.CharField(max_length=20,verbose_name='名称')
    bpub_date = models.DateField(verbose_name='发布日期')
    bread = models.IntegerField(default=0,verbose_name='阅读量')
    bcomment = models.IntegerField(default=0,verbose_name='评论量')
    is_delete = models.BooleanField(default=False,verbose_name='逻辑删除')

    class Meta:
        db_table = 'tb_book' #指明数据库表明
        verbose_name = '图书'  #在admin站点显示的名称
        verbose_name_plural = verbose_name #显示的负数名称

    def __str__(self):
        '''定义每个数据对象的显示信息 '''
        return self.btitle

#定义英雄模型类
class HeroInfo(models.Model):
    GENDER_CHOICES = (
        (0,'female')
        (1,'male')
    )
    hname = models.CharField(max_length=20,verbose_name='名称')
    hgender = models.SmallIntegerField(choices=GENDER_CHOICES,default=0,verbose_name='性别')
    hcomment = models.CharField(max_length=200,null=True,verbose_name='描述信息')   #null=True表示该字段可为空 。那默认的是什么？
    hbook = models.ForeignKey(BookInfo,on_delete=models.CASCADE,verbose_name='图书')  #外键  on_delete=models.CASCADE?
    is_delete = models.BooleanField(default=False,verbose_name='逻辑删除')

    class Meta:
        db_table = 'tb_heros'
        verbose_name = '英雄'
        verbose_name_plural = verbose_name
    def __str__(self):
        return self.name