Re: JSON in 9.2 - Could we have just one to_json() function instead of two separate versions ?

On Fri, 2012-05-04 at 15:59 -0400, Robert Haas wrote:
> On Fri, May 4, 2012 at 3:49 PM, Hannu Krosing <hannu(at)krosing(dot)net> wrote:
> > On Fri, 2012-05-04 at 09:52 -0400, Tom Lane wrote:
> >> Hannu Krosing <hannu(at)2ndQuadrant(dot)com> writes:
> >> > On Wed, 2012-05-02 at 12:06 -0700, Andrew Dunstan wrote:
> >> >> So given that do we do anything about this now, or wait till 9.3?
> >>
> >> > I'd like the json support in 9.2 updated as follows
> >>
> >> I think it's too late to be entertaining proposals for such changes in
> >> 9.2. If we had concluded that the existing functions were actively
> >> wrong or a bad idea,
> >
> > I think that hard-coding "postgresql text" representation as our json
> > representation without a possibility for the user tio easily fix it
> > without rewriting foll xx_to_json() functions is borderline "actively
> > wrong".
> >
> > Can we at least have the xxx_to_json() functions try cast to json first
> > and fall back to text if the cast fails.
>
> I think the idea that you can involve the casting machinery in this is
> misguided. sometextval::json has got to mean that sometextval is
> expected to be in the form of a syntactically correct JSON value - and
> NOT that we wrap it in a JSON string. We can have constructors for
> JSON, but they've got to be separate from the casting machinery.

on the contrary - the string representation of textual value a is "a"

casting should _not_ neam syntax check, casting is by definition a
conversion.

if we cast text to int, we return value of type int , if we cast int to
numeric(5,2) we return value of type numeric(5,2)

why should casring to json work differntly ?

> --
> Robert Haas
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>