Syntax for row_to_json with sqlalchemy
Your query generates an incorrect SQL
SELECT row_to_json(SELECT ... FROM foo) AS detailsFROM (SELECT ... FROM foo) AS details_foo_row_qIt should be
SELECT row_to_json(details_foo_row_q) AS detailsFROM (SELECT ... FROM foo) AS details_foo_row_qYou need to use select as literal_column
from sqlalchemy.sql.expression import literal_columndetails_foo_q = select([ func.row_to_json(literal_column(details_foo_row_q.name)).label('details')]).select_from(details_foo_row_q).where( details_foo_row_q.c.bar_id == Bar.id).alias('details_foo_q')