Re: json support for composites in upcoming 9.2 - Mailing list pgsql-general

On Sat, Aug 11, 2012 at 7:05 AM, jan zimmek <jan.zimmek@web.de> wrote:
> hi,
>
> i am looking into json support of the upcoming 9.2 release and have a question about the row_to_json function. is
therea way to specify the column aliases of a nested composite row without creating a custom type ? 
>
> here is an example:
>
> select
>   row_to_json(t1)
> from (
>   select
>     'joe' as username,
>     row(1, 'prj1') project
> ) t1;
>
> the output is:
>
> {"username":"joe","project":{"f1":1,"f2":"prj1"}}
>
> i want the output to be:
>
> {"username":"joe","project":{"project_id":1,"project_name":"prj1"}}
>
> i thought of something like this:
>
> select
>   row_to_json(t1)
> from (
>   select
>     'joe' as username,
>     (select * from (values(1, 'prj1')) as project(project_id, project_name)) as project
> ) t1;
>
> but this fails with "ERROR: subquery must return only one column".

select
  row_to_json(t1)
from (
  select
    'joe' as username,
    (select project from (values(1, 'prj1')) as project(project_id,
project_name)) as project
) t1;

merlin