Translate SQLite query, with subquery, into Peewee statement

问题

I've got a SQL statement that does what I need, but I'm having trouble converting it into the correlated Peewee statement. Here's the SQL I have now, note that I'm using a subquery right now, but I don't care that it's a subquery either way.

select t.name,
        count(a.type_id) as total,
        (
            select count(id)
            from assignment a
            where a.course_id = 7
            and a.due_date < date()
              and a.type_id = t.id
            group by a.type_id
            order by a.type_id
        ) as completed
from assignment a
inner join type t on t.id = a.type_id
where a.course_id = 7
group by a.type_id
order by a.type_id

Here's the closest I've come to the Peewee statement. Currently I'm aliasing a static number in the query just so that I have a value to work with in my template, so please ignore that part.

Assignment.select(
    Type.name,
    fn.Lower('1').alias('completed'),
    fn.Count(Type.id).alias('total'),
).naive().join(Type).where(
    Assignment.course==self,
).group_by(Type.id).order_by(Type.id)

回答1:

Have you tried just including the subquery as part of the select?

Something like this?

query = (Assignment
 .select(
   Type.name, 
   fn.COUNT(Type.id).alias('total'), 
   Assignment.select(fn.COUNT(Assignment.id)).where(
     (Assignment.due_date < fn.DATE()) & 
     (Assignment.course == 7) &
     (Assignment.type == Type.id)
   ).group_by(Assignment.type).alias('completed'))
 .join(Type)
 .where(Assignment.course == 7)
 .group_by(Type.name))

来源：https://stackoverflow.com/questions/27581826/translate-sqlite-query-with-subquery-into-peewee-statement