Question

I have a Perl script which retrieves data from MySQL Database. this is the code:

sub startSession{
    my $self = shift;

    my $dsn = "dbi:".$self{platform}.":".$self{database}.":".$self{host}.":".$self{port};
    print "$dsn\n" ;
    $self{dbHandle} = DBI->connect($dsn,$user,$password);   
}

I have provided every information from an external file. I get the error message

DBI connect('dbname:**.**.**.**:3306','',...) failed: Access denied for user 'root'@'dbserver' (using password: NO) at line 89

Can't call method "prepare" on an undefined value at at line 97

I am very sure the root can connect from any host and the password is also correct.

Answer 1

First, your immediate problem, is as @Sinan Ünür says, that you need to change $self{platform} to $self->{platform}, etc.

Your second immediate problem is that it appears you’re getting $user and $password from nowhere (they are not passed to the function, so they are undefined unless they are global variables), which would explain the using password: NO part of the error. Maybe those should be $self->{user} and $self->{password}?

You should considering put this at the top of your module, at least during development, to automatically catch errors like these:

use warnings qw(all);
use strict;

But I’d also comment, that from a design perspective, you really ought to treat DSNs as opaque strings. Each database has its own DSN format. So if you ever want to target a different database, you’ll need a different DSN format. Or, possibly, someday MySQL will use a different format (it already has two). Either way, it’ll be much easier to change it one place, in a configuration file, than to track down each place you concatenate the various pieces together.