查询之： __ 及 修改和删除

def date_op(req):

    # 关联查询： 双下划线：————   （如：book__title）

    # 查询多对多
    author_name = models.Book_To_Author.objects.filter(book__title='python').values('author__name')
    print(author_name)

    # name = models.Publish.objects.filter(book__title='python').values('name')
    # print(name)
    #
    # title = models.Book.objects.filter(publisher__name='河南出版社').values('title')
    # print(title)

    # city = models.Book.objects.filter(title='python').values('publisher__city')
    # print(city)

    # 出版社为“河南出版社”的所有名
    # obj = models.Publish.objects.filter(name="河南出版社")[0]
    # print(obj.book_set.values('title').distinct())
    # print(obj.book_set, type(obj.book_set))

    # 书名为go的出版社的地址
    # obj_set = models.Book.objects.filter(title='go')[0]
    # print(obj_set.publisher.name)
    # print(obj_set.publisher.city)

    #  迭代器（性能）
    # if obj_set.iterator():
    #     pass

    #    -- for循环

    # obj_set = models.Book.objects.filter(id=3)
    # for obj in obj_set:
    #     print(obj.title)
    #
    # obj_set.update(title='js')
    # for obj in obj_set:
    #     print(obj.title)

    # 修改
    # models.Book.objects.filter(id=3).update(price=30)

    # 删除
    # models.Book.objects.filter(id=2).delete()

    # models.Book_To_Author.objects.create(
    #     book_id=1,
    #     author_id=2,
    # )

    # dic1 = {"title": "", "price": 35, "color": "yellow"}
    # Book.objects.create(**dic1)

    # Book.objects.create(
    #     title="li漂流记",
    #     price=1,
    #     color="yellow",
    #
    #     publisher_id=4,
    # )

    # book = models.Book.objects.filter(id=2)
    # price = book.values("price")

    # #   某些书绑定某些作者
    # book = models.Book.objects.filter(id=2)[0]
    # authors = models.Author.objects.filter(id_gt=2)
    # # 绑定关系
    # book.author.add(*authors)
    # # 取消关系
    # book.author.remove(*authors)

    return HttpResponse("ok")