Re: BUG #13533: jsonb_populate_record does not work when the value is a simple string

On Tue, Aug 4, 2015 at 5:19 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Paulo Vieira <paulovieira(at)gmail(dot)com> writes:
> > On Mon, Aug 3, 2015 at 5:40 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >> This does not seem like a bug, because the value of the data field is
> >> just abc, and that isn't JSON. You'd need something more like
> >>
> >> input_data json := '{"id": 1, "data": "\"abc\""}';
>
> > I'm confused. In my example the value is <double quotes>abc<double
> quotes>,
> > which is a valid json value (and not simply abc).
>
> No, the value of the field is just abc --- the quotes are JSON syntax
> decoration, they are not part of the represented value. If we do it
> as you seem to have in mind, it would be impossible to deal sanely
> with data values that contain quotes or backslashes.
>
> ​
Paulo,​

​Consider what is stored if you define data as type text. The resultant
value would not include the double-quotes.

The following query fails and for the same reason.

SELECT 'abc'::json

More abstractly:

'{"id": <literal number>, "data": "<literal string>"}'

The value of the <literal string> is what is going to be parsed and so it
must be whatever is needed to make the following pseudo-code succeed.

SELECT <literal string>::json;

​HTH,

David J.
​