Question

好的，我们有三个表：Order，Product和OrderProduct。我想找到Orders有些产品，我写了以下函数：

def get_orders_with_products(products):
    if len(products) < 1:
        raise Exception("at least one product expected")

    query = get_order_set_query(products[0])

    if len(procducts > 1):
        for product in products[1:]:
            query = query & get_order_set_query(product)

    return Order.objects.filter(query)

def get_order_set_query(product):
    product_orders = OrderProduct.objects \
        .values_list('order_id', flat=True)\
        .filter(product=product)
    return Q(id__in=set(product_orders))

此代码将导致类似以下的SQL查询：

select * from Orders
where id in [1, 2, 3]
and id in [2, 3, 4]

有没有办法让Django的ORM编写以下查询？

select * from Orders
where id in (select order_id from OrderProduct where product_id = 1)
and id in (select order_id from OrderProduct where product_id = 2)

有什么建议可以做得更好吗？

Answer 1

是

from django.db.models import Q

queryset = Order.objects.filter(Q(order_id = [1, 2, 3]) & Q(order_id = [2, 3, 4]))

您可以使用

之类的内容替换列表

[id[0] for id in OrderProduct.objects.filter(product_id = 1).values_list('id')]

艾伦

Django ORM - 由多个相关对象和Q查询选择

1 个答案: