Re: how to use require??

Mumia W. Wed, 14 Mar 2007 05:14:09 -0800

On 03/14/2007 05:37 AM, Umar Draz wrote:

HI dear members! I have a file called dbcon.pl into include directory.


#!/usr/local/bin/perl

use DBI;

# Database Username, Password and Driver settings
my $user="konsole";
my $pass="send";
my $host="localhost";
my $driver="mysql";
my $db="treat";
my $tnt="xyz";

# Connect Database
my $dsn = "DBI:$driver:database=$db;host=$host";
my $dbh = DBI->connect($dsn, $user, $pass);

$dsn and $dbh are lexical variables that are restricted to dbcon.pl. Youmight want to consider using package variables. e.g:


our $dbh = ...blah blah

Now I have created a another file login.pl there i include dbcon.pl using 
require.

--------------

#!/usr/local/bin/perl -w

require "include/dbcon.pl";

use warnings;


Missing:
use strict;

use CGI;
use CGI::Session;
my $cgi = new CGI;

my $login = $cgi->param('username');
my $passwd = $cgi->param('password');

print
        $cgi->header().
        $cgi->start_html(-title=>'My Login Page');

if($cgi->param("Submit"))
{
        my $sth = $dbh->prepare(qq{ select username, password from login where 
username=\'$login\' });

If you had enabled strictures ("use strict;"), this line wouldn't havecompiled, and that would've prevented you from making an error.

Since $dbh in dbcon.pl was declared with "my," it was restricted todbcon.pl, and so it wasn't available in login.pl, so $dbh in login.pl asundefined. Undefined values are not objects (well, maybe they are inSmalltalk ;-) , but Perl isn't Smalltalk).

        $sth->execute();

        # Get the Result
        my ($username, $password) = $sth->fetchrow_array();
        $sth->finish();

       # checking valid user name
        if ($username eq $login and $password eq $passwd)
          {
                 print "Your User name and password accepted"
          }

        else { print "Wrong username or password"; }
}

$cgi->end_html;
exit(0);

-----------------------

but when i click on submit button its not working then I saw my apache errors 
logs there was a line.

Name "main::dbh" used only once: possible typo at /var/www/myinventory/login.pl 
line 19.
Can't call method "prepare" on an undefined value at 
/var/www/myinventory/login.pl line 19.

Please help me how i can solve this problem

Regards,

Umar Draz

---------------------------------

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Most Perl programmers would use package variables and the Exporter.

KISS Method:
  In file dbcon.pl:
  our $dbh = DBI->connect($dsn, $user, $pass);

  In file login.pl: (everything stays the same)

Standard Method:
  In file dbcon.pl:
  package Mydbcon;
  use Exporter qw(import);
  @EXPORT = qw($dbh);
  ...
  our $dbh = DBI->connect($dsn, $user, $pass);

  In file login.pl
  require 'include/dbcon.pl';
  import Mydbcon;

Exotic Method :-) :
  In file dbcon.pl: (everything stays the same)

  In file login.pl:
  my $dbh = require 'include/dbcon.pl';

The exotic method relies on the fact that 'require' returns the lastscalar value in the script 'dbcon.pl'; that happens to be $dbh in this case.

The KISS (keep it simple stupid) and exotic methods are easiestprobably, but the standard method is more flexible in the long run. Read"perldoc Exporter" to find out how to use the exporter.


I hope this helps.


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