Re: cast of integer to bool doesn't work (anymore?)

On Fri, 21 Mar 2003, Eric Veldhuyzen wrote:

> On Fri, Mar 21, 2003 at 03:54:56PM -0200, Achilleus Mantzios wrote:
> > On Fri, 21 Mar 2003, Eric Veldhuyzen wrote:
> > 
> > > Hi,
> > > 
> > > Here at my work we use on the production servers PostgreSQL version
> > > 7.2.3, but I have version 7.3.2 (from the Debian distribution) on my
> > > workstation. Now I noticed yesterday that the query 'select 0::boolean;'
> > > works on the production server, it gives the output:
> > > 
> > > # select 0::boolean;
> > >  bool 
> > > ------
> > >  f
> > > (1 row)
> > > 
> > > Perfect. But when I try this on my local version of postgreSQL I get
> > > this:
> > > 
> > > # select 0::boolean;
> > > ERROR:  Cannot cast type integer to boolean
> > 
> > Just wrap 0 with single quotes,
> > e.g.
> > # select '0'::boolean;
> 
> Yeah, I tried that, and yes, that does work from the psql prompt. This
> basically means that I fool psql into thinking that it is a string, and
> then forcing it to cast to a boolean, right? But my problem is that it
> does not work when I use that in the prepare statement from perl. For
> example:
> 
> my $sth = $dbh->prepare(
>     "INSERT INTO object_def (name, meant_as_subobject) VALUES (?,?::bool)");
> $sth->execute('test', 0);
> 
> This code gives me the error
>   "DBD::Pg::st execute failed: ERROR:  Cannot cast type integer to boolean"
> on 7.3, but it works on 7.2 and below. If I change the prepare to 
> 
> my $sth = $dbh->prepare(
>     "INSERT INTO object_def (name, meant_as_subobject) VALUES (?,'?'::bool)");
> 
> I will get the error 
>   "execute called with 2 bind variables, 1 needed" because the
> perl database driver can't handle the quote characters in a prepare statement.

Currently (7.3) all input can be handled if fed as text.
So what you can do is simply:
my $sth = $dbh->prepare(    "INSERT INTO object_def (name, meant_as_subobject) VALUES (?,?)");$sth->execute('test',
'0');


> 
> This here is ofcourse a simplyfied example, in our real project the
> prepare statement is dynamically build by a library that knows the
> database schema, and tries to do conversions while builing
> the prepared statement. One if them is checking the columntypes, and
> replace the ? with ?::bool in the prepared statement if the columntype
> is of boolean type. Another is something similar if the columntype is a
> timestamp or date (I haven't tested if that part still works though, I
> realize now).
> 
> 

-- 
==================================================================
Achilleus Mantzios
S/W Engineer
IT dept
Dynacom Tankers Mngmt
Nikis 4, Glyfada
Athens 16610
Greece
tel:    +30-210-8981112
fax:    +30-210-8981877
email:  achill@matrix.gatewaynet.com       mantzios@softlab.ece.ntua.gr