How can I implement a RESTful API in Perl?

Question

I'm trying to implement a RESTful API in Perl. My current idea is to simply parse the path_info with a regex then dispatch the request to the appropriate subroutine which will then spit out the JSON, XML or even XHTML for the requested resource.

For example to retrieve info about user 1234 the RESTful client should find it at:

http://example.com/model.pl/users/1234

Below is the skeleton code of my first attempt at implementing a RESTful API:

model.pl :

#!/usr/bin/perl -w
use strict;
use CGI;

my $q = CGI->new();

print $q->header('text/html');

my $restfuluri  = $q->path_info;

if      ($restfuluri =~ /^\/(questions)\/([1-9]+$)/) { questions($1, $2); }
elsif   ($restfuluri =~ /^\/(users)\/([1-9]+$)/)     { users($1, $2); }


sub questions
{
      my $object = shift;
      my $value  = shift;

      #This is a stub, spits out JSON or XML when implemented.
      print $q->p("GET question : $object -> $value");
}

sub users
{
      my $object = shift;
      my $value  = shift;

      #This is a stub, spits out JSON or XML when implemented.
      print $q->p("GET user: $object -> $value");
}

Before I proceed any further, I would like to hear from experienced Perl hackers whether I got the basic idea right and if there are any serious shortcomings with this approach in terms of performance.

I can imagine, after a while, the if/else block would grow really large.

Looking forward to hear your views to make this code better.

Answer 1

For lightweight REST APIs I would look at Mojolicious. The request routing is really straightforward and the inbuilt JSON renderer and user agent make development of simple REST APIs very straightforward in my experience.

If your app is going to be relatively small then Mojo::Lite may suit your requirements. For example you may be able to do something like this:

use Mojolicious::Lite;

get '/questions/(:question_id)' => sub {
    my $self = shift;
    my $result = {};
    # do stuff with $result based on $self->stash('question_id')
    return $self->render_json($result)
}

app->start;

Answer 2

The simple solution:

 use CGI;

 my $page  = new CGI;

 if( $ENV{ 'REQUEST_METHOD' } eq 'GET' ){

    my $data = <<json;
    {
    "isbn" : "123456",
    "title" : "Programming Perl",
    "author" : "L. Wall"
     }
 json

     print $page->header('application/json');

     print $data;
 }