我正在尝试将 JSON 数据映射到列。我需要的一切都包含在data
数组中。例子:
{"data":
[
{"stamp":1348249585,"date":"2012-09-21 17:46","blur":"blurs/1.jpg","img":["imgs/1.jpg",[1600,1200]],"thumb":["thumbs/1.jpg",[150,113]]},
{"stamp":1375607177,"date":"2013-08-04 09:06","blur":"blurs/2.jpg","img":["imgs/2.jpg",[1600,1200]],"thumb":["thumbs/2.jpg",[150,113]]},
{"stamp":1376242046,"date":"2013-08-11 17:27","blur":"blurs/3.jpg","img":["imgs/3.jpg",[1600,1200]],"thumb":["thumbs/3.jpg",[150,113]]},
...
目前,我正在使用#>>
具有动态生成条件的运算符:
1) 计算data
数组中的元素个数
2)创建 varchar 数组条件以匹配每个“行”
3) 处理各个行上的元素。
我的解决方案是:
select
json_row,
json_row#>>'{stamp}' as stamp,
json_row#>>'{date}' as date,
json_row#>>'{img,0}' as img,
json_row#>>'{img,1,0}' as img_width,
json_row#>>'{img,1,1}' as img_height,
json_row#>>'{thumb,0}' as thumb,
json_row#>>'{thumb,1,0}' as thumb_width,
json_row#>>'{thumb,1,1}' as thumb_height,
json_row#>>'{thumb,2,0}' as th_x1,
json_row#>>'{thumb,2,1}' as th_y1,
json_row#>>'{thumb,3,0}' as th_x2,
json_row#>>'{thumb,3,1}' as th_y2,
json_row#>>'{blur}'
from
(
select
(gjson#>>c.cond)::json json_row
from
gallery_json
cross join (
select ('{data,'|| generate_series(0,
(select json_array_length((gjson#>>'{data}')::json) from gallery_json) - 1) || '}')::varchar[] cond) c
) rd
这行得通,我可以忍受。但是,鉴于这是我在 PostgreSQL 中使用 JSON 的第一次练习,我想问是否有更好的方法将类似的 JSON 结构映射到行。我认为我应该使用json_populate_recordset
,但到目前为止还没有成功。
SQLFiddle 目前不工作,示例数据:
--drop table if exists gallery_json;
create table gallery_json(gjson json);
insert into gallery_json (gjson)
select '{"data":[
{"stamp":1348249585,"date":"2012-09-21 17:46","blur":"blurs/1.jpg","img":["imgs/1.jpg",[1600,1200]],"thumb":["thumbs/1.jpg",[150,113]]},
{"stamp":1376659268,"date":"2013-08-16 13:21","blur":"blurs/7.jpg","img":["imgs/7.jpg",[1600,539]],"thumb":["thumbs/7.jpg",[267,112],[332,112],[32,0]]},
{"stamp":1376666907,"date":"2013-08-16 15:28","blur":"blurs/8.jpg","img":["imgs/8.jpg",[1600,1200]],"thumb":["thumbs/8.jpg",[150,113]]},
{"stamp":1379016669,"date":"2013-09-12 20:11","blur":"blurs/11.jpg","img":["imgs/11.jpg",[1600,590]],"thumb":["thumbs/11.jpg",[267,112],[304,112],[18,0]]},
{"stamp":1383304027,"date":"2013-11-01 11:07","blur":"blurs/17.jpg","img":["imgs/17.jpg",[1600,1200]],"thumb":["thumbs/17.jpg",[150,113]]}]
,"blur":[600,336],"thumb":{"min":[150,112],"max":[267,200]}}'::json