Re: remaining sql/json patches - Mailing list pgsql-hackers

Hi Anton,

On Tue, Oct 17, 2023 at 4:11 PM Anton A. Melnikov
<a.melnikov@postgrespro.ru> wrote:
> On 17.10.2023 07:02, Amit Langote wrote:
>
> > One thing jian he missed during the debugging is that
> > ExecEvalJsonExprCoersion() receives the EMPTY ARRAY value via
> > *op->resvalue/resnull, set by ExecEvalJsonExprBehavior(), because
> > that's the ON EMPTY behavior specified in the constraint.  The bug was
> > that the code in ExecEvalJsonExprCoercion() failed to set val_string
> > to that value ("[]") before passing to InputFunctionCallSafe(), so the
> > latter would assume the input is NULL.
> >
> Thank a lot for this remark!
>
> I tried to dig to the transformJsonOutput() to fix it earlier at the analyze stage,
> but it looks like a rather hard way.

Indeed.  As I said, the problem was a bug in ExecEvalJsonExprCoercion().

>
> Maybe simple in accordance with you note remove the second condition from this line:
> if (jb && JB_ROOT_IS_SCALAR(jb)) ?

Yeah, that's how I would fix it.

--
Thanks, Amit Langote
EDB: http://www.enterprisedb.com