Re: Cast jsonb to numeric, int, float, bool

On Thu, Mar 29, 2018 at 9:35 AM, Teodor Sigaev <teodor(at)sigaev(dot)ru> wrote:
> Thanks for everyone, pushed with some editorization

I would like to complain about this patch. First, I think that it
would've been a better idea to use functions for this rather than
operators, because now ::text does something totally unlike what ::int
does, and that's confusing. If we had json_to_WHATEVER for various
values of WHATEVER then all of the conversions could be spelled
similarly; as the commit message right points out, the cast can only
do one thing.

Also, I think the error messages aren't great:

+select '[]'::jsonb::bool;
+ERROR: jsonb value must be boolean

In this simple scenario, it's clear enough what has gone wrong, but in
a more complicated case I suspect people will have a hard time
figuring out what the source of that error message is. It seems like
it would be better to say something about casting or converting in the
error message, to give users a clue.

--
Robert Haas
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