Re: to_json(NULL) should to return JSON null instead NULL
От | Andrew Dunstan |
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Тема | Re: to_json(NULL) should to return JSON null instead NULL |
Дата | |
Msg-id | 55E1E7D2.8090508@dunslane.net обсуждение исходный текст |
Ответ на | Re: to_json(NULL) should to return JSON null instead NULL (Pavel Stehule <pavel.stehule@gmail.com>) |
Ответы |
Re: to_json(NULL) should to return JSON null instead NULL
(Pavel Stehule <pavel.stehule@gmail.com>)
|
Список | pgsql-hackers |
On 08/29/2015 12:02 PM, Pavel Stehule wrote: > > > 2015-08-29 15:43 GMT+02:00 Shulgin, Oleksandr > <oleksandr.shulgin@zalando.de <mailto:oleksandr.shulgin@zalando.de>>: > > On Sat, Aug 29, 2015 at 3:39 PM, Tom Lane <tgl@sss.pgh.pa.us > <mailto:tgl@sss.pgh.pa.us>> wrote: > > Andrew Dunstan <andrew@dunslane.net > <mailto:andrew@dunslane.net>> writes: > > On 08/29/2015 08:47 AM, Shulgin, Oleksandr wrote: > >> Given there were no loud complaints about this, the current behavior > >> is appropriate for most users, the rest can still work > around using > >> coalesce(to_json(...), json 'null'). > > > I don't think it's necessarily more correct. But I do agree > that it's > > not a good idea to change the behaviour unless there is major > > unhappiness with it. > > I'm not entirely convinced that JSON NULL and SQL NULL should > be treated > as the same concept, so I would say that the current behavior > is fine --- > at least when you think about it in isolation. However, > haven't we > already bought into that equivalence in these examples? > > regression=# select row_to_json(row(1,null,2)); > row_to_json > --------------------------- > {"f1":1,"f2":null,"f3":2} > (1 row) > > regression=# select array_to_json(array[1,null,2]); > array_to_json > --------------- > [1,null,2] > (1 row) > > or even in to_json itself: > > regression=# select to_json(array[1,null,2]); > to_json > ------------ > [1,null,2] > (1 row) > > The scalar case is definitely failing to be consistent with these. > > > Yes, that's my argument for correctness also: to_json() on a > composite object should behave like distribution of to_json() > calls over object/array elements. > > Is consistency a sufficient reason to change it? > > > Not for me. > > > It is bug - and it should be fixed. I agree, so this change is too > strong for fixing in minor version - but we can change it in > unreleased major versions - 9.5 and master. No, frankly that's being far too free with the word bug. It's not even unambiguously incorrect. Note that all the to_json functions are strict. In this sense it's quite consistent. If we change it to being called on null input, what should we return if a null non-scalar is passed in? cheers andrew
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