django ManyToMany字段

django ManyToMany字段

可以把多對多字段寫在filter裏面，會自動把所有的都比較一遍，拿出結果
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：某本書中總共出現了多少個張三：
    b1 = Book.objects.get(book_name="俠客行")
    b1.objects.filter(books__name="張三").count()