Re: casting BOOL to somthng

On Aug 31, 2004, at 6:06 PM, sad wrote:

> why BOOL can not be casted to TEXT
> ....nevertheless BOOL has a textual (output) representation 't' and
> 'f' letters
> why not to use this fact to define cast to TEXT ?

I'm not sure of the reason why there isn't a built-in cast from boolean
to text, though I'm not a big fan of casts in general so it doesn't
really bother me too much. If this is something you desire, I believe
you can use CREATE CAST to make your own cast from boolean to text.

test=# select true::text;
ERROR: cannot cast type boolean to text

create or replace function bool_to_text (boolean)
returns text
strict
language sql as '
select case
when $1 then \'t\'
else \'f\'
end;
';

create cast (boolean as text)
with function bool_to_text(boolean)
as assignment;

test=# select true::text;
text
------
t
(1 row)

You can find more information at
<http://www.postgresql.org/docs/current/static/sql-createcast.html>

Hope this helps!

Michael Glaesemann
grzm myrealbox com