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Catalyst-Manual-5.701002
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/ Catalyst::Manual::Tutorial::Intro

NAME

Catalyst::Manual::Tutorial::Intro - Catalyst Tutorial - Part 1: Introduction

OVERVIEW

This is Part 1 of 9 of the Catalyst Tutorial.

Tutorial Overview

  1. Introduction

  2. Catalyst Basics

  3. Basic CRUD

  4. Authentication

  5. Authorization

  6. Debugging

  7. Testing

  8. Advanced CRUD

  9. Appendices

DESCRIPTION

This tutorial provides a multipart introduction to the Catalyst web framework. It seeks to provide a rapid overview of many of its most commonly used features. The focus is on the real-world best practices required in the construction of nearly all Catalyst applications.

Although the primary target of the tutorial is users new to the Catalyst framework, experienced users may wish to review specific sections (for example, how to use DBIC for their model classes or how to add authentication and authorization to an existing application).

You can obtain the code for all the tutorial examples from the catalyst subversion repository by issuing the command:

svn co http://dev.catalyst.perl.org/repos/Catalyst/tags/examples/Tutorial/MyApp/5.7/ CatalystTutorial

This will download the current code for each tutorial chapter in the CatalystTutorial directory. Each example application directory has the same name as the tutorial chapter.

These reference implementations are provided so that when you follow the tutorial, you can use the code from the subversion repository to ensure that your system is set up correctly, and that you have not inadvertently made any typographic errors, or accidentally skipped part of the tutorial.

Additionally, if you're reading this manual online, you can download the example program and all the necessary dependencies to your local machine by installing the Task::Catalyst::Tutorial distribution from CPAN:

cpan Task::Catalyst::Tutorial

This will also test to make sure the dependencies are working. If you have trouble installing these, please ask for help on the #catalyst IRC channel, or the Catalyst mailing list.

Subjects covered include:

  • A simple application that lists and adds books.

  • The use of DBIx::Class (DBIC) for the model.

  • How to write CRUD (Create, Read, Update, and Delete) operations in Catalyst.

  • Authentication ("auth").

  • Role-based authorization ("authz").

  • Attempts to provide an example showing current (5.7XXX) Catalyst practices. For example, the use of Catalyst::Action::RenderView, DBIC, Catalyst::Plugin::ConfigLoader with myapp.yml, the use of lib/MyApp/Controller/Root.pm vs. lib/MyApp.pm, etc.

  • The use of Template Toolkit (TT) and the Catalyst::Helper::View::TTSite view helper.

  • Useful techniques for troubleshooting and debugging Catalyst applications.

  • The use of SQLite as a database (with code also provided for MySQL and PostgreSQL).

  • The use of HTML::Widget for automated form processing and validation.

This tutorial makes the learning process its main priority. For example, the level of comments in the code found here would likely be considered excessive in a "normal project". Because of their contextual value, this tutorial will generally favor inline comments over a separate discussion in the text. It also deliberately tries to demonstrate multiple approaches to various features (in general, you should try to be as consistent as possible with your own production code).

Furthermore, this tutorial tries to minimize the number of controllers, models, TT templates, and database tables. Although this does result in things being a bit contrived at times, the concepts should be applicable to more complex environments. More complete and complicated example applications can be found in the examples area of the Catalyst Subversion repository at http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/.

Note: There are a variety of other introductory materials available through the Catalyst web site and at http://dev.catalyst.perl.org/wiki/UserIntroductions and http://dev.catalyst.perl.org/.

VERSIONS AND CONVENTIONS USED IN THIS TUTORIAL

This tutorial was built using the following resources. Please note that you may need to make adjustments for different environments and versions:

  • OS = CentOS 4 Linux (RHEL 4)

  • Catalyst v5.7

    = item *

    Catalyst::Devel v1.02

  • DBIx::Class v0.06003

  • Catalyst Plugins

    The plugins used in this tutorial all have sufficiently stable APIs that you shouldn't need to worry about versions. However, there could be cases where the tutorial is affected by what version of plugins you use. This tutorial has been tested against the following set of plugins:

    • Catalyst::Plugin::Authentication -- 0.09

    • Catalyst::Plugin::Authentication::Store::DBIC -- 0.07

    • Catalyst::Plugin::Authorization::ACL -- 0.08

    • Catalyst::Plugin::Authorization::Roles -- 0.04

    • Catalyst::Plugin::ConfigLoader -- 0.13

    • Catalyst::Plugin::HTML::Widget -- 1.1

    • Catalyst::Plugin::Session -- 0.12

    • Catalyst::Plugin::Session::State::Cookie -- 0.05

    • Catalyst::Plugin::Session::Store::FastMmap -- 0.02

    • Catalyst::Plugin::StackTrace -- 0.06

    • Catalyst::Plugin::Static::Simple -- 0.14

  • Since the web browser is being used on the same box where Perl and the Catalyst development server is running, the URL of http://localhost:3000 will be used (the Catalyst development server defaults to port 3000). If you are running Perl on a different box than where your web browser is located (or using a different port number via the -p port_number option to the development server), then you will need to update the URL you use accordingly.

  • Depending on the web browser you are using, you might need to hit Shift+Reload to pull a fresh page when testing your application at various points. Also, the -k keepalive option to the development server can be necessary with some browsers (especially Internet Explorer).

CATALYST INSTALLATION

Unfortunately, one of the most daunting tasks faced by newcomers to Catalyst is getting it installed. Although a compelling strength of Catalyst is that it can easily make use of many of the modules in the vast repository that is CPAN, this can result in initial installations that are both time consuming and frustrating. However, there are a growing number of methods that can dramatically ease this undertaking. Of these, the following are likely to be applicable to the largest number of potential new users:

  • Matt Trout's cat-install

    Available at http://www.shadowcatsystems.co.uk/static/cat-install, cat-install can be a quick and painless way to get Catalyst up and running. Just download the script from the link above and type perl cat-install.

  • Chris Laco's CatInABox

    Download the tarball from http://handelframework.com/downloads/CatInABox.tar.gz and unpack it on your machine. Depending on your OS platform, either run start.bat or start.sh.

  • Pre-Built VMWare Images

    Under the VMWare community program, work is ongoing to develop a number of VMWare images where an entire Catalyst development environment has already been installed, complete with database engines and a full complement of Catalyst plugins.

For additional information and recommendations on Catalyst installation, please refer to Catalyst::Manual::Installation.

NOTE: Step-by-step instructions to replicate the environment on which this tutorial was developed can be found at Catalyst::Manual::Installation::CentOS4. Using these instructions, you should be able to build a complete CentOS 4.X server with Catalyst and all the plugins required to run this tutorial.

DATABASES

This tutorial will primarily focus on SQLite because of its simplicity of installation and use; however, modifications in the script required to support MySQL and PostgreSQL will be presented in Appendix 2.

Note: One of the advantages of the MVC design patterns is that applications become much more database independent. As such, you will notice that only the .sql files used to initialize the database change between database systems: the Catalyst code generally remains the same.

WHERE TO GET WORKING CODE

Each part of the tutorial has complete code available in the main Catalyst Subversion repository (see the note at the beginning of each part for the appropriate svn command to use). Additionally, the final code is available as a ready-to-run tarball at http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/Tutorial/Final_Tarball/MyApp.tgz.

NOTE: You can run the test cases for the final code with the following commands:

wget http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/Tutorial/Final_Tarball/MyApp.tgz
tar zxvf MyApp.tgz
cd MyApp
CATALYST_DEBUG=0 prove --lib lib  t

AUTHOR

Kennedy Clark, hkclark@gmail.com

Please report any errors, issues or suggestions to the author. The most recent version of the Catalyst Tutorial can be found at http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Manual/lib/Catalyst/Manual/Tutorial/.

Copyright 2006, Kennedy Clark, under Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/2.5/).