从非结构化 JSON 数据中获取键和值

Question

我有以下 table 和一些数据：

Table:

create table tbl_jsontest
(
   id int,
   jdata json 
);

记录：

insert into tbl_jsontest values(1,'{"Id":1,"Name":"Jack"}');
insert into tbl_jsontest values(1,'[{"Id":2,"Name":"Mak"},{"Name":"Aez","Address":"ZX"}]');
insert into tbl_jsontest values(1,'[{"Id":5,"Name":"Lee"}]');

查询：

SELECT json_data.key AS key1,
       json_data.value AS value1
FROM tbl_jsontest, 
json_each_text(tbl_jsontest.jdata) AS json_data;

出现错误：

ERROR: cannot deconstruct an array as an object

Answer 1

json_each_text 函数将 json 对象作为输入，不适用于数组。

文档https://www.postgresql.org/docs/current/functions-json.html

json_each_text ( json ) → setof record ( key text, value text ) 将顶级 JSON 对象扩展为一组 key/value 对。返回值将是文本类型。

可以先用json_array_elements展开数组，再展开对象

您还应该将 jdata 重新格式化为相同的格式

记录：

insert into tbl_jsontest values(1,'[{"Id":1,"Name":"Jack"}]');
insert into tbl_jsontest values(1,'[{"Id":2,"Name":"Mak"},{"Name":"Aez","Address":"ZX"}]');
insert into tbl_jsontest values(1,'[{"Id":5,"Name":"Lee"}]');

查询：

select t.id, key, value
from (SELECT id, json_array_elements(tbl_jsontest.jdata) d
      FROM tbl_jsontest) t,
     json_each_text(t.d);

结果：

+--+-------+-----+
|id|key    |value|
+--+-------+-----+
|1 |Id     |2    |
|1 |Name   |Mak  |
|1 |Name   |Aez  |
|1 |Address|ZX   |
|1 |Id     |5    |
|1 |Name   |Lee  |
|1 |Id     |1    |
|1 |Name   |Jack |
+--+-------+-----+

从非结构化 JSON 数据中获取键和值

Get key and value from unstructured JSON data

json

postgresql

postgresql-11