Hello Robert, > 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.
This is not entirely accurate. ::text casts any jsonb to text, e.g:
```
select '{}'::jsonb::text;
text
------
{}
(1 row)
```
This is exactly what ::bool and ::numeric casts do. Naturally not every
jsonb value can be represented as boolean or numeric though.
> 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.
I believe it's not as convenient for users as having casts. Also this
would be inconsistent with the rest of the system since we already have
int4 -> text, int4 -> bool and various other casts.
> 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.
I agree. How about "unable to cast jsonb value to %typename%"?
--
Best regards,
Aleksander Alekseev
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