Re: 9.3 Json & Array's

> On 24 September 2013 at 13:46 Andrew Dunstan <andrew(at)dunslane(dot)net> wrote:
>
>
> Feel free to ask questions.
>
> The heart of the API is the event handlers defined in this stuct in
> include/utils/jsonapi.h:
>
> typedef struct JsonSemAction
> {
> void *semstate;
> json_struct_action object_start;
> json_struct_action object_end;
> json_struct_action array_start;
> json_struct_action array_end;
> json_ofield_action object_field_start;
> json_ofield_action object_field_end;
> json_aelem_action array_element_start;
> json_aelem_action array_element_end;
> json_scalar_action scalar;
> } JsonSemAction;
>
>
> Basically there is a handler for the start and end of each non-scalar
> structural element in JSON, plus a handler for scalars.
>
> There are several problems that will be posed by processing nested
> arrays and objects, including:
>
> * in effect you would need to construct a stack of state that could be
> pushed and popped

True.

> * JSON arrays aren't a very good match for SQL arrays - they are
> unidimensional and heterogenous.

This is true, but I think one would have to start with an assumption that the
data is valid for an SQL type and then check again once one gets it done.
JSON is a pretty flexible format which makes it a poor match in many cases
for SQL types generally. But I think the example so far (with
json_populate_recordset) is a good one, namely a best effort conversion.

>
>
> I'm not saying this can't be done - it will just take a bit of effort.

Yeah, looking through the code, I think it will be more work than I originally
thought but that just means it will take longer.
>
> cheers
>
> andrew
>
>
>
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Best Wishes,
Chris Travers
http://www.2ndquadrant.com
PostgreSQL Services, Training, and Support