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

OK -- so i have mod_perl set up, created a startup.pl that looks something like this: 
#!/usr/local/bin/perl

use strict;

use lib qw( /webcontent/server_home/rentsavers/test );

$ENV{MOD_PERL} or die "not running mod_perl!:  $! \n";

use Apache::Registry;

use Apache::DBI ();
use DBI ();
# Initialize the database connections for each child
Apache::DBI->connect_on_init
   ("DBI:mysql:database=test;host=localhost",
   "testuser",
   {
    PrintError => 1, # warn() on errors
    RaiseError => 0, # don't die on error
    AutoCommit => 1, # commit executes immediately
   }
  );

1;

[download]
from reading the perldoc, the online guide, and Writing Apache Modules w/ Perl and C ... i can use DBI normally in a handler, and the caching, etc is transparent. but i'm not seeing anything DBI-related with this handler: 
package My::Greeting;
  use strict;

  use Apache::Constants qw(OK);
  use Data::Dumper;
  use DBI;

  sub handler {
      my $r = shift;
      my $now = scalar localtime;
      my $server_name = $r->server->server_hostname;

      $r->send_http_header('text/plain');

      print <<EOT;
  Thanks for visiting $server_name.
  The local time is $now.
EOT

      my $DBH || DBI->connect( "dbi:mysql:localhost", "rentsaver", "ro
+ot" ) ;

      Dumper( $DBH );
      return OK;
  }

1;

[download]
am i missing something really obvious? or is there a bigger problem?

Replies are listed 'Best First'.
Re: accessing Apache::DBI 'cached connections'
by bobn (Chaplain) on Jul 21, 2003 at 20:56 UTC

    If you weren't using Apache::DBI, then your code:

    my $DBH || DBI->connect( "dbi:mysql:localhost", "rentsaver", "root" ) ;

    probably should have been:

    $DBH ||= DBI->connect( "dbi:mysql:localhost", "rentsaver", "root" ) ;

    [download]

    You lost the equal part of the assignment operator. This code may create a connection, but it doesn't set $DBH.

    But since you are using Apache::DBI, it should probably be: 

    $DBH = DBI->connect( "dbi:mysql:localhost", "rentsaver", "root" ) ;

    [download]

    Also, your startup file need only use Apache::DBI, not DBI; Apache::DBI loads DBI, then overrides the connect and discoonnect methods to implement the caching for you.

    --Bob Niederman, http://bob-n.com
[reply]
[d/l]
[select]
      well, i removed the double-load of DBI ...

      i should get *some* output from Data::Dumper if i've connected. another script on the same server ( non-mod_perl ) give me: 

      $VAR1 = bless( {}, 'DBI::db' );

      [download]
      so i'm lost ...
[reply]
[d/l]

        Apache::DBI works transparently, so if one scripts works, and the other doesn't, then there must be differences in the way you connect in the two scripts. In other words a script that works without Apache::DBI must also work with Apache::DBI!

        Try the following bit of code and see what you get...

        #!/usr/bin/perl

use CGI qw/:standard/;
use DBI;
use Data::Dumper;

$Apache::DBI::DEBUG = 2;  # Turn on Apache::DBI debugging

print header,
      start_html('Testing Apache::DBI'),
      h1('Testing Apache::DBI');

my $dbh;
eval {
  $dbh = DBI->connect( "DBI:mysql:database=test;host=localhost", undef
+, undef, { RaiseError => 1 } ) ;
};

if ($@) {
  print p('DBI Error: '.$@);
} else {
  print p('Connect success');
  print p("We are using Apache::DBI") if $dbh->isa('Apache::DBI::db');
  print pre(Dumper($dbh));
}

print end_html();

        [download]

        When I call that with Apache::DBI enabled, I get the following:

        Testing Apache::DBI

Connect success

We are using Apache::DBI

$VAR1 = bless( {}, 'Apache::DBI::db' );

        And in my error log I get:

        13692 Apache::DBI need ping: yes
13692 Apache::DBI new connect to 'database=test;host=localhostAutoCommit=1PrintError=1RaiseError=1'

        Cheers,

        Cees

        Update: Looks like this got solved while I was writing my test script. I guess I'll have to be quicker next time...

[reply]
[d/l]
        In your example, $DBH is just an empty lexical variable that you declared right before dumping it. The DBI->connect code will never even run because "my $DBH" will always return true. (It returns the result of the my() call, not the value of the variable.)

        UPDATE: Advice about the return value of my() is not correct. See below.

[reply]

        Did you also fix the module code so that you are actually assigning the return value of DBI->connect to $DBH?

        --Bob Niederman, http://bob-n.com
[reply]
Re: accessing Apache::DBI 'cached connections'
by hardburn (Abbot) on Jul 21, 2003 at 20:45 UTC

    ???

    my $DBH || DBI->connect( "dbi:mysql:localhost", "rentsaver", "ro
+ot" ) ;

    [download]

    There's your DBI right there. Except it should be my $DBH = DBI-> . . ..

    Update: Changed double '==' to a single '=' (oops!)

    ----
    I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
    -- Schemer

    Note: All code is untested, unless otherwise stated

[reply]
[d/l]
[select]
      well, for one it should be a single =, not a double, i'd think.

      i 'borrowed' the line of code out of the _Writing ... _ book. supposedly there's a global $DBH variable.

      i've changed the || to =, but still no stuff in $DBH.

[reply]
        No, you're reading something wrong. There is no global $DBH variable unless you declare one.
[reply]

        You're right, should have been a single =.

        ----
        I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
        -- Schemer

        Note: All code is untested, unless otherwise stated

[reply]
Re: accessing Apache::DBI 'cached connections'
by geektron (Curate) on Jul 21, 2003 at 20:47 UTC
    i did miss one obvious thing in the handler: 
    print Dumper( $DBH );

    [download]
    but i still have an empty database handle ...
[reply]
[d/l]

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