django ManyToMany字段

django ManyToMany字段

可以把多对多字段写在filter里面，会自动把所有的都比较一遍，拿出结果
如：

class Book(object):
    book_name = models.CharField(max_length=15)
    star = models.IntegerField()
    visible = models.BooleanField()


class Hero(object):
    hero_name = models.CharField(max_length=15)
    power = models.IntegerField()
    visible = models.BooleanField()
    books = models.ManyToMany(Book, on_delete=models.CASCASE)

查：某本书中总共出现了多少个张三：
    b1 = Book.objects.get(book_name="侠客行")
    b1.objects.filter(books__name="张三").count()