Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I wrote a class for basic Database access functionallity: 
package MyDB_DB;

use DBI;
use constant DBI_STRING => 'dbi:mysqlPP:plant;merlin','uname','passwor
+d';

my $dbh;

sub DB_connect
{
    $dbh = DBI->connect( DBI_STRING )
        ||    die "Cannot connect: $DBI::errstr\n";
    #return $dbh;
}

sub DB_prepare
{
    my $statement = pop;
    #print 'PlantDB_DB: '.$statement."\n";
    my $sth = $dbh->prepare($statement) ||
        die "Cannot prepare statement: $DBI::errstr\n";
    return $sth;
}

sub DB_execute
{
    my $sth = pop;
    $sth->execute ||
        die "Cannot execute statement:  $DBI::errstr\n";
}


sub DB_finish
{
$dbh->disconnect;
}


sub new 
{
   my $self = {};
   bless $self;
   return $self;
}

return 1;

[download]
in my main program i make an instance of that class and call the functions. when the program ends, i get the following message: (in cleanup) Can't call method "close" on an undefined value at ..../mysqlPP.pm line 274 during global destruction. maybe this is a problem related to oo-programming, maybe not. but i dont know how to deal with that message. Can you help? Regards, misu

Replies are listed 'Best First'.
Re: DBI Can't call method "close" during global destruction
by nite_man (Deacon) on Mar 24, 2003 at 12:39 UTC
    You should store a database handler into your object property: 
    sub DB_connect
{
    my $self = shift;
    $self->{dbh} = DBI->connect( DBI_STRING )
        ||    die "Cannot connect: $DBI::errstr\n";    
}

sub DB_finish
{
    my $self = shift;
    $self->{dbh}->disconnect;
}

    [download]

    For understanding Perl OO, please see Tutorials::Object Oriented Perl.
    If you need to have a superstructure over DBI, it's enough to make it as module not necessary to create a class. 
          
-------->
SV* sv_bless(SV* sv, HV* stash);

    [download]
[reply]
[d/l]
[select]
      I also suggest: 
      sub DB_finish
{
    my $self = shift;
    if (defined($self->{dbh})) {
        $self->{dbh}->disconnect;
    }
}

      [download]
      because if the database connect fails or is not called the dbh variable will be undefined and the same error will occur again.

      Regards,
      Marcel
[reply]
[d/l]

Back to Seekers of Perl Wisdom