I created a function in Perl called pg_dt, that will convert PostgreSQL's datetime values into Perl's DateTime values and vice versa. This is useful both when you want to store DateTime values into the database, or want to convert the pg datetime/timestamp value from the database into a DateTime object value that Perl can use.
Perl v5.40 introduced native true and false keywords. Unfortunately not all CPAN modules are ready to use them. One of those not yet ready is Mojo::Pg.
Normally you'd want to pass booleans to your queries as just 1's and 0's. However, since Mojo::JSON's true & false stringify to 1 and 0, my 5.38-using codebase is full of Mojo::Pg queries with Mojo::JSON's true and false as arguments.
This is a problem if I want to upgrade the perl interpreter of that project to Perl v5.40, because if I write "use v5.40;" in the file that contains those boolean keywords, Perl's builtin booleans will be used instead, which don't stringify to 1 and 0, but to 1 and the empty string, which can't be used by DBD::Pg in boolean fields and makes DBD::Pg throw an exception.
The solution I found was to subclass Mojo::Pg::Database, and wrap the query method, so that if Perl's builtin booleans are found, they are replaced in the query with native Pg booleans.
This is the subclass:
package Local::My::Pg::Database;
use v5.40;
use Mojo::Base 'Mojo::Pg::Database';
use DBD::Pg ':pg_types';
use experimental 'builtin';
sub query {
my ($self, $query) = (shift, shift);
my $cb = ref $_[-1] eq 'CODE' ? pop : undef;
my @args = map { builtin::is_bool($_) ? { type => PG_BOOL, value => $_ ? 1 : 0 } : $_ } @_;
return $self->SUPER::query($query, @args, $cb // ());
}
...which requires the Mojo::Pg object to be told to use it:
$pg->database_class('Local::My::Pg::Database');
This solved my problem.
The other module I had problems with on Perl v5.40 is Mojolicious::Plugin::OpenAPI, which doesn't let the builtin booleans to be used in the API spec. I wrote a patch for that, and might submit it to the author.
Other than those, Mojo::JSON does not stringify builtin booleans to booleans, but to 1 and "" UNLESS Cpanel::JSON::XS is installed, then it works fine.
Have you found other CPAN modules that need to be updated for Perl v5.40's booleans?
This block of code is valid Perl:
if (my $var1 = calc1()) {
say $var1;
} elsif (my $var2 = calc2()) {
say "$var1, $var2";
}
As you can see, $var1, which is declared in the if clause, is visible inside the elsif clause too.
Perl never ceases to amaze me!
Welcome. As you will hopefully find out in this blog, Perl is the best language in the world.
#!/usr/bin/env perl
print "Hello, world!\n";