Postgres的SQL查詢，在關聯數組它將組字段

Question

例如：我有表的「入場券」

id, int 
client_id, int 
client_name, text 

而不是通常的選擇（「選擇ID，CLIENT_ID，CLIENT_NAME FROM票」）我需要的東西，會給作爲結果：

{ 
    "id": 2, 
    "client": { 
     "id": 31, 
     "name": "Mark" 
    } 
} 

Answer 1

如果你喜歡使用SQL這一點，有json_build_object function：

SELECT 
    json_build_object(
    'id', id, 
    'client', json_build_object(
     'id', client_id, 
     'name', client_name)) 
FROM 
    tickets; 

例：

#!/usr/bin/env python 

import psycopg2 
import json 

conn = psycopg2.connect('') 
cur = conn.cursor() 
cur.execute(""" 
    with tickets(id, client_id, client_name) as (values(1,2,'x'),(3,4,'y')) 
    SELECT 
     json_build_object(
     'id', id, 
     'client', json_build_object(
      'id', client_id, 
      'name', client_name)) 
    FROM 
     tickets; 
    """) 

for row in cur.fetchall(): 
    print row, json.dumps(row[0]) 

輸出：

 
({u'client': {u'id': 2, u'name': u'x'}, u'id': 1},) {"client": {"id": 2, "name": "x"}, "id": 1} 
({u'client': {u'id': 4, u'name': u'y'}, u'id': 3},) {"client": {"id": 4, "name": "y"}, "id": 3}