On 07.01.2018 00:33, Pavel Stehule wrote:
2018-01-06 22:23 GMT+01:00 Nikita Glukhov <n.glu...@postgrespro.ru
<mailto:n.glu...@postgrespro.ru>>:
On 07.01.2018 00:22, Pavel Stehule wrote:
Hi
I try jsonpath on json
{
"book":
[
{
"title": "Beginning JSON",
"author": "Ben Smith",
"price": 49.99
},
{
"title": "JSON at Work",
"author": "Tom Marrs",
"price": 29.99
},
{
"title": "Learn JSON in a DAY",
"author": "Acodemy",
"price": 8.99
},
{
"title": "JSON: Questions and Answers",
"author": "George Duckett",
"price": 6.00
}
],
"price range":
{
"cheap": 10.00,
"medium": 20.00
}
}
I am not jsonpath expert, so I can be bad
How I can get title of book with cost 6?
postgres=# select j @* '$.book[*] ? (@.price==6)' from test;
┌─────────────────────────────────────────────────────┐
│ ?column? │
╞═════════════════════════════════════════════════════╡
│ { ↵│
│ "title": "JSON: Questions and Answers",↵│
│ "author": "George Duckett", ↵│
│ "price": 6.00 ↵│
│ } ↵│
│ │
└─────────────────────────────────────────────────────┘
(1 row)
-- not sure, if it is correct
postgres=# select j @* '$.book[*].title ? (@.price==6)' from test;
┌──────────┐
│ ?column? │
╞══════════╡
└──────────┘
(0 rows)
I found some examples, where the filter has bigger sense, but it
is not supported
LINE 1: select j @* '$.book[?(@.price==6.00)].title' from test;
^
DETAIL: syntax error, unexpected '?' at or near "?"
".title" simply should go after the filter:
select j @* '$.book[*] ? (@.price==6.00).title' from test;
It is working, thank you.
and the form "$.book[?(@.price==6.00)].title" ? I found this example
in some other SQL/JSON implementations.
This is non-standard feature, but it can be easily added for
compatibility with other implementations.
--
Nikita Glukhov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
