PostgreSQL 9.3+上的JSON，太丑了吗？ [英] JSON at PostgreSQL 9.3+, it is so ugly?

问题描述

有某种不太丑陋的选项可以将字符串作为文本 s和整数作为 int s？

There are kind of "less ugly" option to get strings as texts and integers as ints?

所有 JSON树的叶子都具有众所周知的数据类型，那么，如何对PostgreSQL说看数据类型？

All leaves of a JSON-tree have well known datatypes, so, how to say to PostgreSQL to see the datatypes?

示例和丑陋的解决方案...丑陋的解决方案较少？

Examples of problems and UGLY solutions... There are less ugly solution?

SELECT version(); -- PostgreSQL 9.3

CREATE TABLE example (
  id serial PRIMARY KEY,
  info JSON 
);
INSERT INTO example (info) VALUES
  ('{"aa":10,"bb":"nonono nononon"}'),
  ('{"aa":10,"x":"etc"}'),  
  ('{"aa":9,"x":"etc etc"}');

-- SIX ERROS... But human-readable syntax
SELECT DISTINCT info->'aa' FROM example;    -- ex.1
SELECT * FROM example ORDER BY info->'aa';  -- ex.2
SELECT info->'x' FROM example WHERE info->'x' IS NOT NULL; -- ex.3
SELECT * FROM example WHERE info->'x'='etc';  -- ex.4
SELECT * FROM example WHERE (info->'x')::text='etc';  -- ex.5
SELECT * FROM example WHERE info->'aa'=10;  -- ex.6

-- UGLY (!!) six workarounds
SELECT DISTINCT (info->'aa')::text FROM example;        -- ex.1
SELECT * FROM example ORDER BY (info->'aa')::text::int; -- ex.2
SELECT info->'x' FROM example WHERE (info->'x')::text IS NOT NULL; -- ex.3
SELECT * FROM example WHERE trim((info->'x')::text,'"')='etc';  -- exs. 4 and 5
SELECT * FROM example WHERE (info->'aa')::text::int=10;  -- ex.6

推荐答案

使用->> json运算符，它以 text 。

SELECT DISTINCT info->>'aa' FROM example;
SELECT * FROM example ORDER BY info->>'aa';
SELECT info->>'x' FROM example WHERE (info->>'x') IS NOT NULL;
SELECT * FROM example WHERE info->>'x'='etc';
SELECT * FROM example WHERE (info->>'aa')::int=10;  -- still needs a cast to int

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