Thread: potential bug in JSON
I've found a potential bug. Why the "->" operator returns JSON instead of TEXT? It doesn't make sens for me, and the documentation doesn't inform about that.
postgres=# SELECT ('{"id": 1}'::json -> 'id')::int;
ERROR: cannot cast type json to integer
LINE 1: SELECT ('{"id": 1}'::json -> 'id')::int;
postgres=# SELECT ('{"id": 1}'::json -> 'id')::text::int;
int4
------
1
(1 row)
postgres=# SELECT version();
version
---------------------------------------------------------------------------------------------------------------
PostgreSQL 9.3beta1 on x86_64-unknown-linux-gnu, compiled by gcc (Ubuntu/Linaro 4.7.3-1ubuntu1) 4.7.3, 64-bit
(1 row)
On 05/28/2013 11:38 AM, Szymon Guz wrote:
> I've found a potential bug. Why the "->" operator returns JSON instead
> of TEXT? It doesn't make sens for me, and the documentation doesn't
> inform about that.
>
> postgres=# SELECT ('{"id": 1}'::json -> 'id')::int;
> ERROR: cannot cast type json to integer
> LINE 1: SELECT ('{"id": 1}'::json -> 'id')::int;
>
> postgres=# SELECT ('{"id": 1}'::json -> 'id')::text::int;
> int4
> ------
> 1
> (1 row)
>
>
>
This is not a bug. It is documented and by design.
If you want text, use the ->> operator. That's exactly what it's for.
cheers
andrew
On 05/28/2013 08:38 AM, Szymon Guz wrote: > I've found a potential bug. Why the "->" operator returns JSON instead of > TEXT? It doesn't make sens for me, and the documentation doesn't inform > about that. Yes, it most certainly does: http://www.postgresql.org/docs/9.3/static/functions-json.html If you want to get text, use the ->> operator. -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com
On 28 May 2013 17:53, Josh Berkus <josh@agliodbs.com> wrote:
On 05/28/2013 08:38 AM, Szymon Guz wrote:Yes, it most certainly does:
> I've found a potential bug. Why the "->" operator returns JSON instead of
> TEXT? It doesn't make sens for me, and the documentation doesn't inform
> about that.
http://www.postgresql.org/docs/9.3/static/functions-json.html
If you want to get text, use the ->> operator.
Yea, I noticed that. It was a little bit misleading for me that "->" is for getting field and "->>" is for getting field as text. Especially when "->"::TEXT doesn't return the same value as "->>".
Maybe there should be added "as JSON" to those operators which don't return text?
Szymon