migrations_app.pl

use Mojolicious::Lite;
use Mojo::Pg;
use 5.20.0;
use experimental 'signatures';

helper pg => sub { state $pg = Mojo::Pg->new('postgresql://postgres@/test') };

# Prepare a table during startup
app->pg->migrations->from_this_class->migrate;

get '/' => sub ($c) {

  my $db = $c->pg->db;
  my $ip = $c->tx->remote_address;

  # Store information about current visitor blocking
  $db->query('insert into visitors values (now(), ?)', $ip);

  # Retrieve information about previous visitors non-blocking
  $db->query('select * from visitors limit 50' => sub ($db, $err, $results) {

    return $c->reply->exception($err) if $err;

    $c->render(json => [$results->hashes->each]);
  });
};

app->start;
__DATA__

@@ migrations
-- 1 up
create table if not exists visitors (at timestamp, ip varchar(255));
-- 1 down
drop table if exists visitors;