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Re: Re: SQL/JSON: functions

Alexander Korotkov <a.korotkov@postgrespro.ru>

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From: Alexander Korotkov <a.korotkov@postgrespro.ru>
To: Andrew Alsup <bluesbreaker@gmail.com>
Cc: Nikita Glukhov <n.gluhov@postgrespro.ru>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Andres Freund <andres@anarazel.de>, Dmitry Dolgov <9erthalion6@gmail.com>, Pavel Stehule <pavel.stehule@gmail.com>, Oleg Bartunov <obartunov@postgrespro.ru>, Michael Paquier <michael@paquier.xyz>, Simon Riggs <simon@2ndquadrant.com>, Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Date: 2019-05-17T00:56:44Z
Lists: pgsql-hackers 
Hi!

On Tue, May 14, 2019 at 3:54 AM Andrew Alsup <bluesbreaker@gmail.com> wrote:
> array slicing [0:], [:1], and [0:1] do not work:$.c1.c2[0:].b3
>
> # select json_path_query('{"a1": 123, "b1": "xxx", "c1": {"a2": 456,
> "b2": "yyy", "c2": [{"a3": 777, "b3": "7z"},{"a3": 888, "b3":
> "8z"}]}}'::json, '$.c1.c2[0:].b3'::jsonpath);
> 2019-05-13 20:47:48.740 EDT [21856] ERROR:  bad jsonpath representation
> at character 147
> 2019-05-13 20:47:48.740 EDT [21856] DETAIL:  syntax error, unexpected
> ':', expecting ',' or ']' at or near ":"
> 2019-05-13 20:47:48.740 EDT [21856] STATEMENT:  select
> json_path_query('{"a1": 123, "b1": "xxx", "c1": {"a2": 456, "b2": "yyy",
> "c2": [{"a3": 777, "b3": "7z"},{"a3": 888, "b3": "8z"}]}}'::json,
> '$.c1.c2[0:].b3'::jsonpath);
> ERROR:  bad jsonpath representation
> LINE 1: ...7, "b3": "7z"},{"a3": 888, "b3": "8z"}]}}'::json, '$.c1.c2[0...
>                                                               ^
> DETAIL:  syntax error, unexpected ':', expecting ',' or ']' at or near ":"

There is no color syntax from array slicing in jsonpath.  Instead of
"[0:]" one should write "[0 to last]".  See documentation
https://www.postgresql.org/docs/devel/datatype-json.html#TYPE-JSONPATH-ACCESSORS

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. JSON_TABLE: Add support for NESTED paths and columns

  2. Add basic JSON_TABLE() functionality

  3. Add SQL/JSON query functions

  4. Add soft error handling to some expression nodes

  5. Adjust populate_record_field() to handle errors softly

  6. Refactor code used by jsonpath executor to fetch variables

  7. Add more SQL/JSON constructor functions

  8. SQL/JSON: support the IS JSON predicate

  9. SQL/JSON: add standard JSON constructor functions

  10. Improve readability of SQL/JSON documentation.

  11. Documentation for SQL/JSON features

  12. RETURNING clause for JSON() and JSON_SCALAR()

  13. SQL JSON functions

  14. SQL/JSON query functions

  15. IS JSON predicate

  16. SQL/JSON constructors

  17. Common SQL/JSON clauses

  18. Doc: remove obsolete entries in table of BRIN strategy numbers.

  19. Doc: standardize markup a bit more.

  20. Make pg_regress.c unset PGDATABASE during make installcheck.

  21. Fix handling of GENERATED columns in CREATE TABLE LIKE INCLUDING DEFAULTS.