How do I encode HTTP GET query strings in Perl?

Question

This question is somewhat related to What’s the simplest way to make a HTTP GET request in Perl?.

Before making the request via LWP::Simple I have a hash of query string components that I need to serialize/escape. What's the best way to encode the query string? It should take into account spaces and all the characters that need to be escaped in valid URIs. I figure it's probably in an existing package, but I'm not sure how to go about finding it.

use LWP::Simple;
my $base_uri = 'http://example.com/rest_api/';
my %query_hash = (spam => 'eggs', foo => 'bar baz');
my $query_string = urlencode(query_hash); # Part in question.
my $query_uri = "$base_uri?$query_string";
# http://example.com/rest_api/?spam=eggs&foo=bar+baz
$contents = get($query_uri);

Answer 1

URI::Escape is probably the most direct answer, as other have given, but I would recommend using a URI object for the entire thing. URI automatically escapes the GET parameters for you (using URI::Escape).

my $uri = URI->new( 'http://example.com' );
$uri->query_form(foo => '1 2', bar => 2);
print $uri; ## http://example.com?foo=1+2&bar=2

As an added bonus, LWP::Simple's get function will take a URI object as it's argument instead of a string.

Answer 2

URI::Escape does what you want.

use URI::Escape;

sub escape_hash {
    my %hash = @_;
    my @pairs;
    for my $key (keys %hash) {
        push @pairs, join "=", map { uri_escape($_) } $key, $hash{$key};
    }
    return join "&", @pairs;
}