krace@hotbox /m/u/code> cat json_pg.py
import psycopg2


def run(stmt):
     cur =  psycopg2.connect(database='test', user='postgres', password='password', host='localhost').cursor()
     cur.execute(stmt)
     result = cur.fetchall()
     print(list(result))


stmt = 'select cast(row_to_json(row) as text) from (select book.id, book.name, book.author_id, author.name as author_name from book inner join author on book.author_id = author.id) row;'
run(stmt)
krace@hotbox /m/u/code> python json_pg.py
[('{"id":1,"name":"War and Peace","author_id":1,"author_name":"Leo Tolstoy"}',),
 ('{"id":2,"name":"The Trial","author_id":2,"author_name":"Kafka"}',),
 ('{"id":3,"name":"The metamorphosis","author_id":2,"author_name":"Kafka"}',)]