Re: json function question

On Wednesday, February 24, 2016, Andrew Dunstan <andrew(at)dunslane(dot)net> wrote:

>
>
> On 02/24/2016 09:11 AM, David G. Johnston wrote:
>
>> On Wednesday, February 24, 2016, Andrew Dunstan <andrew(at)dunslane(dot)net
>> <mailto:andrew(at)dunslane(dot)net>> wrote:
>>
>>
>> Having json(b)_populate_record recursively process nested complex
>> objects would be a large undertaking. One thing to consider is
>> that json arrays are quite different from Postgres arrays: they
>> are essentially one-dimensional heterogenous lists, not
>> multi-dimensional homogeneous matrices. So while a Postgres array
>> that's been converted to a json array should in principle be
>> convertible back, an arbitrary json array could easily not be.
>>
>>
>> An arbitrary json array should be one-dimensional and homogeneous - seems
>> like that should be easy to import. The true concern is that not all
>> PostgreSQL arrays are capable of being represented in json.
>>
>
>
>
> Neither of these things are true AFAIK.
>
> 1. The following is a 100% legal json array, about as heterogenous as can
> be:
>
> [ "a" , 1, true, null, [2,false], {"b": null} ]
>
>
> 2. Having implemented the routines to convert Postgres arrays to json I'm
> not aware of any which can't be converted. Please supply an example of one
> that can't.
>
>
Yeah, I confused heterogeneous and homogeneous. That said we already only
promise best effort so if presented with a non-complex array it would be
nice to import it as part of that effort. Even if something more complex
cannot be and continues to fail.

David J.