SQLAlchemy：一个 "all-inclusive" in_

Question

在通常的 Customer -> Orders 示例模式中，如果我们想要获得所有下订单的客户 order_category_id 设置为 12 或 13，我们会告诉 SQLAlchemy。 ..

for customer in db.query(Customer)\
        .join(Order, Customer.id = Order.cst_id)\
        .filter(Order.order_category_id.in_([12,13]):
    # do something with customer
    ...

但是，如果我们想要获得所有 Customers，这使得 Orders 具有 12 和 13 order_category_id秒？在 SQL 中，我将其写为：

select * 
from Customer
where 
   exists (select 1 from Order 
    where Customer.id = Order.cst_id and Order.order_category_id = 12)
   and exists (select 1 from Order 
    where Customer.id = Order.cst_id and Order.order_category_id = 13)

如何触发 SQLAlchemy 生成此类查询？即与 12 和 13 的订单行关联的一个返回客户实体 category_ids?

Answer 1

像这样：

subq1 = (
    Customer.query
    .join(Order, Customer.id = Order.cst_id)
    .filter(Order.order_category_id == 12)
).subquery()

final_query = (
    query(subq1)
    .join(Order, Customer.id = Order.cst_id)
    .filter(Order.order_category_id == 13)
)

我还没有测试过这个，但我认为它应该可以。

SQLAlchemy：一个 "all-inclusive" in_

SQLAlchemy: An "all-inclusive" in_

sqlalchemy