Mojo::Pg in Non-blocking sequential

[jeydurai]

• Mojo::Pg version: 2.28
• Perl version: 5.24.0
• Operating system: Windows10

  Steps to reproduce the behavior

$app->helper(auth3 => sub {
        my ($self) = @_;
        my $pg = $self->pg;
        my $db = $self->pg->db;
        my $param_username = $self->param('username');
        my $param_pass = $self->param('password');
        my $sql = "SELECT * FROM mojo_users WHERE username='$param_username'";
        print "$sql\n";
        $self->delay(
            sub {
                my $delay = shift;
                print "I am in first Sub\n";
                $db->query($sql, $delay->begin);
            },
            sub {
                my ($delay, $err, $results) = @_;
                print "I am in second Sub\n";
                print "$err\n";
                my $result = $results->hash;
                my $username_db = $result->{username};
                my $pass_db = $result->{password};
                if ($param_username eq $username_db and 
                    $self->bcrypt_validate($param_pass, $pass_db)) {
                    $self->stash(username => $param_username);
                    $self->session(
                        username => $param_username,
                        menu1 => 'Home',
                        menu2 => 'Jeyaraj Durairaj',
                        menu3 => 'Admin',
                        menu4 => 'Settings',
                        menu5 => 'Signout',
                        b_menu1 => 'About',
                        b_menu2 => 'Raptor',
                        b_menu3 => 'NormaliTor',
                        b_menu4 => 'UploadImus',
                        b_menu5 => 'MapTor',
                        b_menu6 => 'ReporNychus',
                        b_menu7 => 'ModelOvi'
                    );
                    return $self->redirect_to('/home');
                } else {
                    $self->flash(err => $err || 'Username/Password Incorrect!');
                    return $self->redirect_to('/');
                }

        });
});

Expected behavior

It should help me to fetch user credentials from PostgreSQL, validate and render my page

Actual behavior

I get [error] Can't dup: Bad file descriptor at C:/Strawberry/perl/site/lib/Mojo/Pg/Database.pm line 130, line 2231.

[kraih]

Can you reduce the problem to a minimal self-contained test case?

[jeydurai]

I have given below the reduced to the minimal self-contained case.

use Mojolicious::Lite;
use Mojo::Pg;
plugin 'Bcrypt';

post '/signin' => sub {
    my $self = shift;
    my $pg = Mojo::Pg->new('postgresql://postgres@/mysourcedata');
    my $db = $pg->db;
    my $param_username = $self->param('username');
    my $param_pass = $self->param('password');
    my $sql = "SELECT * FROM mojo_users WHERE username='$param_username'";
    $self->delay(
        sub {
            my $delay = shift;
            $db->query($sql, $delay->begin);
        },
        sub {
            my ($delay, $err, $results) = @_;
            my $result = $results->hash;
            my $username_db = $result->{username};
            my $pass_db = $result->{password};
            if ($param_username eq $username_db and 
                $self->bcrypt_validate($param_pass, $pass_db)) {

                $self->session(username => $param_username);
                return $self->redirect_to('/home');
            } else {
                $self->flash(err => $err || 'Username/Password Incorrect!');
                return $self->redirect_to('/');
            }

    });
    $c->render_later;
};

[kraih]

Is Mojolicious::Plugin::Bcrypt really necessary to replicate the problem?

[kraih]

my $sql = "SELECT * FROM mojo_users WHERE username='$param_username'";

Side note, you should never interpolate user generated data into SQL strings, that's an SQL injection vulnerability. Always use placeholders!

[jeydurai]

Mojolicious::Plugin::Bcrypt is not necessary to replicate the problem as you pointed out. Placeholders did not work at all. I tried for almost a half day. Hence as a resort to emergency, I used the interpolation. I will either correct it myself or comeback if I face the same problem again.

However, for me, now, the non blocking query is the major issue. Because, my application is going to be utilising this. Please help me.

[kraih]

Afraid i can't replicate the problem, could be Strawberry Perl specific.