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Re: json api WIP patch

Hannu Krosing <hannu@krosing.net>

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From: Hannu Krosing <hannu@krosing.net>
To: Andrew Dunstan <andrew@dunslane.net>
Cc: Peter Eisentraut <peter_e@gmx.net>, Robert Haas <robertmhaas@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2013-02-04T23:42:45Z
Lists: pgsql-hackers 
On 01/31/2013 11:20 PM, Andrew Dunstan wrote:
>
> I'm happy to take opinions about this, and I expected
> some bikeshedding, but your reaction is contrary to
> everything others have told me. Mostly they love the operators.
What I would really like is if we extended postgresql core and made
a few more constructs definable as overloadable operator:

1) array / dictionary element lookup
   a[b]
  CREATE OPERATOR [] (...)

2) attribute lookup
   a.b
  CREATE OPERATOR . (...)

then you could make json lookups either step-by-step using

CREATE OPERATOR [] (
     PROCEDURE = json_array_lookup, LEFTARG = json, RIGHTARG = int)

and

CREATE OPERATOR [] (
     PROCEDURE = json_dict_lookup, LEFTARG = json, RIGHTARG = text)

fourthname = myjson[4]['name']


or perhaps a single


CREATE OPERATOR [] (
     PROCEDURE = json_deep_lookup, LEFTARG = json, RIGHTARG = VARIADIC 
"any")

fourthname = myjson[4, 'name']


though I suspect that we do not support type VARIADIC "any" in operator 
definitions

---------
Hannu



> I guess that '~>' and '~>>' would work as well as '->' and '->>'.
>
>
> cheers
>
> andrew
>
>