postgresql - JSONB sqlalchemy 聚合函数

Question

我想使用 SQLAlchemy 重现可用的 aggregate function来自子查询的 jsonb_object_agg sq_objects:

from sqlalchemy import select, func
s = select([
    sq_objects.c.object_id,
    func.jsonb_object_agg(
        sq_objects.c.keys, sq_objects.c.values).over(
        partition_by=sq_objects.c.object_id).label("attributes"),
]).\
    distinct(sq_objects.c.object_id)

但是，执行返回:

(psycopg2.ProgrammingError) can't adapt type 'method'

[ SQL: "SELECT DISTINCT ON (sq_objects.object_id)
     sq_objects.object_id,
     jsonb_object_agg(
         %(jsonb_object_agg_1)s,
         %(jsonb_object_agg_2)s
     ) OVER (PARTITION BY sq_objects.object_id) AS attributes
 FROM (SELECT ... ) AS sq_objects"
] [
parameters: {'jsonb_object_agg_1': <bound method Properties.keys of <sqlalchemy.sql.base.ImmutableColumnCollection object at 0x7f0ffb7aa828>>,
             'jsonb_object_agg_2': <bound method Properties.values of <sqlalchemy.sql.base.ImmutableColumnCollection object at 0x7f0ffb7aa828>>}]

这是我要重现的sql代码:

SELECT DISTINCT ON (sq_objects.object_id)
    sq_objects.object_id,
    jsonb_object_agg(
        sq_objects.keys,
        sq_objects.values
    ) OVER (PARTITION BY sq_objects.object_id) AS attributes
FROM (SELECT ... ) AS sq_objects

Answer 1

问题在于属性 keys 和 values 是不可变列集合 sq_objects.c 的方法。该问题的另一种解决方案是使用项目访问符号来获取实际列:

func.jsonb_object_agg(
    sq_objects.c["keys"],
    sq_objects.c["values"]
).over(
    partition_by=sq_objects.c.object_id
).label("attributes")