12
Oct/090

use HTML::FormHandler;

I’ve been meaning to give HTML::FormHandler a try for quite some time now. Over the weekend I converted a form from some home-grown form validation and html generation to use HTML::FormHandler instead. HTML::FormHandler was inspired by, and quasi-forked from, Form::Processor. There are many options for processing forms, such as FormValidator::Simple (Catalyst’s default) and Data::FormValidator, to name a few.

Up until now I’ve always thought that the existing form handling/validating modules on CPAN were incredibly lacking. They all have these crazy and inconsistent APIs that in the end limit what you are able to do. I don’t expect a form validation API to handle every possible situation, but I do expect it to provide a consistent API that is well documented and allows me to easily extend if I need additional functionality. Plus none of them use Moose (AFAIK), which isn’t just me being a Moose evangelist, its also practical because Moose provides mechanisms to extend functionality via roles and to provide reusable validation with MooseX::Types.

HTML::FormHandler solves these issues. HTML::FormHandler can be a complete end-to-end solution for declaring form fields and types, applying server-side validation, generating the HTML for a form, and applying form submits to the database. Almost everything and the kitchen sink is there, except client-side form validation, which can be added separately of course. Normally a “do everything” package scares me, especially for something like form validation. But, Gerda Shank (the author of HTML::FormHandler) did a great job splitting out the various pieces of HTML::FormHandler so that any piece of the form handling process can be subverted to your own needs, and there is copious amounts of documentation explaining how to do so.

The HTML::FormHandler::Manual::Intro does a great job introducing HTML::FormHandler.

There are a few downsides to this module’s current state. It is relatively new and is still stabilizing. For example, just recently the results of form validation were separated from the form object itself. This is a huge fundamental change, but a necessary one. Also, the concept of widgets was recently introduced. Widgets are a great way to extend and customize the display of form fields, and the form as a whole. But, this was just introduced and is still experimental, and has some rough edges. Despite this, the widget design is very promising and I ended up using it myself (thanks to HTML::FormHandler::Manual::Rendering) as my preferred rendering method.

Enjoy.

Tagged as: , ,
No Comments
9
Sep/093

Top 10 Reasons to use Perl

You should use Perl because…

10. Real Perl coders don’t have fohawks.
9. Perl has nothing to do with Ryan Seacrest.
8. Beer improves Perl.
7. It comes with a 20-sided die for all that TIMTOWTDI.
6. It has nothing to do with PHP.
5. Captain Picard writes perl.
4. There is no better place to get Moo seX.
3. It grows on you.
2. IE8 was not written in Perl.

… drum roll …

1. You can write this.

Tagged as: , , , , , ,
3 Comments
28
Jul/092

Upgrading to Catalyst 5.8

Over the last few days at $work I’ve been upgrading Catalyst from 5.7 to 5.8. This new version of catalyst, released in April, has been completely overhauled to use Moose for it’s OO system, among other enhancements and bug fixes.

I found that the Catalyst::Manual::CatalystAndMoose manual was a great starting point to using Moose with Catalyst. Also, Catalyst::Upgrading has specific points to consider when upgrading to 5.8. During the initial install of Catalyst 5.8 I was told that I had a few related modules installed, that while not Catalyst prerequisites, I should upgrade them as they were known to fail on the new Catalyst. I was lucky that I caught this message, as cpan did not pause to wait for me to read it and went on its marry way building, testing, and installing Catalyst.

Once installed I went ahead and also upgraded some related modules we use such as Catalyst::Plugin::Authentication, DBIx::Class, Catalyst::Plugin::Session, Catalyst::Authentication::Store::DBIx::Class, etc. This way I could test all these upgrades all at once instead of one at a time.

Next I modified all my custom plugins to use MRO::Compat instead of Class::C3 per the documentation in Class::C3::Adopt::NEXT. But, then I realized I might as well just rewrite all my plugins as Moose::Roles as its pretty easy to convert a plugin to a role and you end up with much cleaner code.

I started Apache up and things mostly worked. There were a few backwards incompatibilities that I wasn’t aware of, such as there were a few cases where developers had done this:

sub index : Local { }

Instead of:

sub index : Private { }

In our previous version of catalyst (5.7) using :Local, while not documented, worked just like :Private if the subroutine was named index. In 5.8 only :Private will cause a handler named index to be the default handler if the URL resolves to the controller only. This was an easy fix. There were a couple other small issues, but nothing major. I found and fixed a bug in Catalyst::Model::DBIC::Schema and added the support for the compute() method to Catalyst::Plugin::Cache. Both of these changes reduced the amount of changes I needed to make to my own code.

A couple hours in to it I was upgraded and everything was working. Of course I spent the next few days upgrading/enhancing/rewriting Catalyst bits that could be done much more elegantly, and with less code, using Moose.

On a side note, during the upgrade I found this great quote in Catalyst::Model::Adaptor:

Catalyst is glue, not a way of life!

Amen! Most people, myself included, start out by writing all their business logic in their Controllers because that is what MVC told them to do. Don’t do it! Catalyst is meant to be a GLUE – most of your application should be written in a way that it doesn’t give a flying crap how, or by whom, it is used. Put your business logic in modules that optionally expose themselves as Models (perhaps via Catalyst::Model::Adaptor) or just by adding a use statement in your controller that then uses that module. Your controllers should be little more than code to glue a data source with the view and provide some input validation.

I’ve been waiting a long time for this Moosification and its been a joy working with this new Catalyst. Next up to bat will be the Moosification of DBIx::Class! Think we’ll get it by Christmas? :)

Don’t forget to buy the new Catalyst Book! If purchasing from Amazon make sure you follow this link to ensure that the Enlightened Perl Organisation gets a cut of the sale.

Tagged as: , ,
2 Comments
24
Jun/092

use Moose;

If you’re used to regular OO perl you’ll recognize this:

package Dog;
use strict;
use warnings;

sub new {
    my ($class, %args) = @_;
    $args{name} ||= 'Spot';
    return bless \%args, shift;
}

sub bark {
    my ($self) = @_;
    print $self->{name} . " barks!\n";
}

1;

With Moose this becomes drastically simpler and more powerful:

package Cat;
use Moose;

has 'name' => (is=>'ro', isa=>'Str', default=>'Fluffy');

sub meow {
    my ($self) = @_;
    print $self->name() . " meows!\n";
}

1;

You may hear that Moose is slow. Don’t let that throw you off, it only adds a fraction of a second to startup time, and is exceptionally fast during run-time. There are much more important things to be concerned about. Moose will make your code cleaner, easier to change and extend, and makes coding perl oo quite enjoyable.

Tagged as: ,
2 Comments

Recent Posts

Iron Man

Links

RSS Planet Perl Iron Man Posts

RSS bluefeet @ github

Perl Ads

RSS Perl Jobs

Tags

Calendar

March 2010
M T W T F S S
« Jan    
1234567
891011121314
15161718192021
22232425262728
293031