Add some additonal info about DBIC relationships

[catagits/Catalyst-Manual.git] / lib / Catalyst / Manual / Tutorial / 01_Intro.pod

=head1 NAME

Catalyst::Manual::Tutorial::01_Intro - Catalyst Tutorial - Chapter 1: Introduction


=head1 OVERVIEW

This is B<Chapter 1 of 10> for the Catalyst tutorial.

L<Tutorial Overview|Catalyst::Manual::Tutorial>

=over 4

=item 1

B<01_Introduction>

=item 2

L<Catalyst Basics|Catalyst::Manual::Tutorial::02_CatalystBasics>

=item 3

L<More Catalyst Basics|Catalyst::Manual::Tutorial::03_MoreCatalystBasics>

=item 4

L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD>

=item 5

L<Authentication|Catalyst::Manual::Tutorial::05_Authentication>

=item 6

L<Authorization|Catalyst::Manual::Tutorial::06_Authorization>

=item 7

L<Debugging|Catalyst::Manual::Tutorial::07_Debugging>

=item 8

L<Testing|Catalyst::Manual::Tutorial::08_Testing>

=item 9

L<Advanced CRUD|Catalyst::Manual::Tutorial::09_AdvancedCRUD>

=item 10

L<Appendices|Catalyst::Manual::Tutorial::10_Appendices>

=back


=head1 DESCRIPTION

This tutorial provides a multi-part 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, how to add
authentication and authorization to an existing application, or form
management).

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/trunk/examples/Tutorial/ CatalystTutorial

This will download the most recent code for each chapter of the
tutorial into the CatalystTutorial directory on your machine.

B<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.>

B<NOTE: You can use any Perl-supported OS and environment to run 
Catalyst.> It should make little or no difference to Catalyst's 
operation, B<but this tutorial has been written using the Debian 5 
live CD> because that represents a quick and easy way for most people to 
try out Catalyst with virtually zero setup time and hassles.  Also, 
the tutorial has been tested to work correctly with the versions of 
Catalyst and all the supporting modules in Debian 5 (see "VERSIONS 
AND CONVENTIONS USED IN THIS TUTORIAL" below for the specific versions 
for some of the key modules), so B<if you think you might be running 
into an issue related to versions> (for example, a module changed its 
behavior in a newer version or a bug was introduced), B<it might be 
worth giving Debian 5 a try>.

If you plan to follow along with Debian 5, you can jump down to the 
"Debian" section under L</"CATALYST INSTALLATION"> below and it will walk you 
though the setup of a fully functional Catalyst environment. If you 
would prefer to install directly from CPAN, you can download the example 
program and all the necessary dependencies to your local machine by 
installing the C<Task::Catalyst::Tutorial> distribution: 

     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 by the tutorial include:

=over 4

=item * 

A simple application that lists and adds books.

=item *

The use of L<DBIx::Class|DBIx::Class> (DBIC) for the model (including 
some of the more advanced techniques you will probably want to use in 
your applications).

=item * 

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

=item *

Authentication ("auth").

=item * 

Role-based authorization ("authz").

=item * 

Attempts to provide an example showing current (5.8XXX) Catalyst
practices. For example, the use of 
L<Catalyst::Action::RenderView|Catalyst::Action::RenderView>,
DBIC, L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> 
with C<myapp.conf>, the use of C<lib/MyApp/Controller/Root.pm> 
vs. C<lib/MyApp.pm>, etc.

=item * 

The use of Template Toolkit (TT).

=item * 

Useful techniques for troubleshooting and debugging Catalyst
applications.

=item * 

The use of SQLite as a database (with code also provided for MySQL and
PostgreSQL).  (Note: Because we make use of the DBIx::Class Object 
Relational Mapping [ORM] layer, out our application will be database
agnostic and can easily be used by any of the databases supported
by DBIx::Class.)

=item * 

The use of L<HTML::FormFu|HTML::FormFu> or L<HTML::FormHandler|HTML::FormHandler>
for automated form processing and validation.

=back

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 C<examples> area of the Catalyst
Subversion repository at
L<http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/>.


=head1 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 (note that trailing zeros in version numbers are not 
significant and may get dropped with techniques for viewing them;
for example, Catalyst v5.80020 might show up as 5.8002):

=over 4

=item * 

Debian 5 (Lenny)

=item * 

Catalyst v5.80020 (note: may show up as '5.8002' without the trailing zero)

=item *

Catalyst::Devel v1.26

=item * 

DBIx::Class v0.08115

=item *

Template Toolkit v2.20

=item * 

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:

=over 4

=item * 

Catalyst::Plugin::Authentication -- v0.10016

=item *

Catalyst::Plugin::Authorization::Roles -- v0.08

=item *

Catalyst::Plugin::ConfigLoader -- v0.27

=item *

Catalyst::Plugin::Session -- v0.29

=item *

Catalyst::Plugin::Session::State::Cookie -- v0.17

=item *

Catalyst::Plugin::Session::Store::FastMmap -- v0.13

=item *

Catalyst::Plugin::StackTrace -- v0.11

=item *

Catalyst::Plugin::Static::Simple -- v0.28

=back

=item * 

B<NOTE:> You can check the versions you have installed with the
following command:

    perl -M<_mod_name_> -e '"print $<_mod_name_>::VERSION\n"'

For example:

    perl -MCatalyst -e 'print "$Catalyst::VERSION\n";'

or:

    perl -MCatalyst::Devel -e 'print "$Catalyst::Devel::VERSION\n";'

=item * 

This tutorial will assume that the web browser is located on the same 
system where the Catalyst development server is running, and 
therefore use a URL of C<http://localhost:3000> (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 C<-p> I<port_number> option to the 
development server), then you will need to update the URL you use 
accordingly.

Please Note: Depending on the web browser you are using, you might 
need to hit C<Shift+Reload> or C<Ctrl+Reload> to pull a fresh page 
when testing your application at various points (see 
L<http://en.wikipedia.org/wiki/Bypass_your_cache> for a comprehensive 
list of options for each browser).  Also, the C<-k> keepalive option 
to the development server can be necessary with some browsers 
(especially Internet Explorer).

=back


=head1 CATALYST INSTALLATION

Although Catalyst installation has been a challenge in the past, the 
good news is that there are a growing number of options to eliminate 
(or at least dramatically simplify) this concern.  Although a 
compelling strength of Catalyst is that it makes use of many of the 
modules in the vast repository that is CPAN, this can complicate the 
installation process if you approach it in the wrong way.  Consider 
the following suggestions on the most common ways to get started with 
a Catalyst development environment:

=over 4

=item *

Debian

The Debian 5 live CD represents a great way for newcomers to 
experiment with Catalyst.  As a "live CD," you can simple boot from 
the CD, run a few commands, and in a matter of minutes you should have 
a fully function environment in which do this tutorial. B<The tutorial 
was fully tested to work under Debian 5.  Although it SHOULD work 
under any Catalyst installation method you might choose, it can be 
hard to guarantee this.>

=over 4

=item * 

Download one of the ISO files from 
L<http://cdimage.debian.org/cdimage/release/current-live/i386/iso-cd/>
(the current version at the time this was written was 5.0.3). 
You can pick any one of the live CD variations will work, but 
you may wish to consider the following points:

=over 4

=item *

"C<debian-live-503-i386-rescue.iso>" is probably the best all-around 
option for most people because it includes many extra tools such as 
the GCC compiler, therefore saving RAM (every package you need to 
install when running from live CD consumes memory because RAM disk is 
being used in lieu of real disk space).  When initially booting under 
this image, you may see some cryptic warning messages having to do 
with various diagnostic tools it tries to load or enable, but you 
should be able to safely ignore these.

=item *

"C<debian-live-503-i386-standard.iso>" is a great option because of 
its compact size, but you will probably need approximately 1 GB of RAM 
in the computer where you will run the tutorial.  Because the 
"standard" live CD comes with with a minimal set of tools, we will 
have to install extra packages (such as the GCC compiler), all of 
which will require RAM when running from a live CD. 

=item *

The other ISO images include different flavors of X-Windows desktop 
managers.  You can select one of these if you don't mind the larger 
download size and prefer a graphical environment.  Be aware that these 
disks do not come with the extra tools found on the "rescue" image, so 
you will need adequate RAM to be able to install them just as you 
would under the "standard" image. B<Use one of the "graphical" ISO 
images if you want a graphical web browser on the same machine as 
where you will run the tutorial.>  (If you are using one of the non-
graphical images discussed above, you can still use a graphical web 
browser from another machine and point it to your Catalyst development 
machine.)

=back

=item *

Boot off the CD.

=item *

Select "C<Live>" from the initial boot menu.

=item *

Once the system has booted to a "C<user@debian:~$>" prompt, first
install the Subversion client in case you want to check out the
completed chapter example code:

	sudo aptitude -y install subversion

Then enter the following command to add the more current "unstable" 
package repository so we get the latest versions of Catalyst and
related packages:

    sudo vi /etc/apt/sources.list

Add the following line to the bottom of this file:

    deb http://ftp.us.debian.org/debian/ unstable main

If you are not familiar with VI, you can move to the bottom of this 
file and press the "o" key to insert a new line and type the line 
above.  Then press the "Esc" key followed by a colon (":"), the 
letters "wq" and then the "Enter" key.  The rest of the tutorial will 
assume that you know how to use some editor that is available from the 
Linux command-line environment.

=item *

Install Catalyst:

    sudo aptitude update
    sudo aptitude -y install sqlite3 libdbd-sqlite3-perl libcatalyst-perl \
        libcatalyst-modules-perl libdbix-class-timestamp-perl \
        libdatetime-format-sqlite-perl libconfig-general-perl \
        libhtml-formfu-model-dbic-perl libterm-readline-perl-perl \
        libdbix-class-encodedcolumn-perl

Let it install (normally about a 30 to 90-second operaton) and you are 
done. (Note the '\' above.  Depending on your environment, you might 
be able to cut and paste the text as shown or need to remove the '\' 
characters to that the command is all on a single line.)

If you are using an image other than the "rescue" ISO, you will also need
to run the following command to install additional packages:

    sudo aptitude -y install gcc make libc6-dev

If you are running from the Live CD, you probably also want to free up 
some RAM disk space with the following:

    sudo aptitude clean

NOTE: While the instructions above mention the Live CD because that 
makes it easy for people new to Linux, you can obviously pick a 
different Debian ISO image and install it to your hard drive. 
Although there are many different ways to download and install Debian, 
the "netinst" ISO image (such as "C<debian-500-i386-netinst.iso>" 
represents a great option because it keeps your initial download small 
(but still let's you install anything you want "over the network").

Here are some tips if you are running from a live CD and are running
out of disk space (which really means you are running out of RAM):

=over 4

=item *

Always run "C<aptitude clean>" after you install new packages to 
delete the original .deb files (the files installed B<by> the .deb 
package B<will> remain available, just the .deb package itself is 
deleted).

=item *

If you are installing modules from CPAN, you can free up some space 
with "C<rm -rf /root/.cpan/*>" (change "/root/" in the previous 
command to match your home directory or the location where CPAN
has been configured to perform build operations).

=item *

If necessary, you can remove the cached package information with the 
command "C<rm -f /var/lib/apt/lists/*>".  You can later pull this 
information again via the command "C<aptitude update>".

=item * 

You can save a small amount of space by commenting out the lines in 
C</etc/apt/sources.list> that reference "deb-src" and 
"security.debian.org".  If you have already done an "C<aptitude 
update>" with these repositories enabled, you can use the tip in the 
previous bullet to free the space up (and then do another "C<aptitude 
update>").

=item *

Although you can free up space by removing packages you installed 
since you last booted (check out "C<aptitude remove _pkg_name>"), 
don't bother trying to remove packages already available at the time 
of boot. Instead of freeing up space, it will actual I<consume> some 
space. (The live CD uses these "burn in" packages right from the CD 
disk vs. first loading them on the virtual RAM disk. However, if you 
remove them, the system has to update various files, something that 
I<does> consume some space on the virtual RAM disk.)

=back

=back

=item *

Ubuntu

Ubuntu is an extremely popular offshoot of Debian.  It provides 
cutting edge versions of many common tools, application and libraries 
in an easy-to-run live CD configuration (and because a single download 
option can be used for both live CD and install-to-disk usage, it 
keeps your download options nice and simple).  As with Debian 5, you 
should be able to generate a fully function Catalyst environment in a 
matter of minutes.  Here are quick instructions on how to use Ubuntu 
to prepare for the tutorial:

=over 4

=item * 

Download the Ubuntu Desktop edition and boot from the CD and/or image 
file, select your language, and then "Try Ubuntu without any changes 
to your computer."

=item *

Open a terminal session (click "Applications" in the upper-left 
corner, then "Accessories," then "Terminal").

=item *

Add the 'universe' repositories:

    sudo gedit /etc/apt/sources.list

And remove the comments from the lines under the comments about the
'universe' repositories.

=item *

Install Catalyst:

    sudo aptitude update
    sudo aptitude install libdbd-sqlite3-perl libcatalyst-perl libcatalyst-modules-perl libconfig-general-perl

Accept all of the dependencies.  Done.  

If you are running from the Live CD, you probably also want to free up 
some disk space with the following:

    sudo aptitude clean

NOTE: While the instructions above mention the live CD because that 
makes it easy for people new to Linux, you can obviously also use one 
of the options to install Ubuntu on your drive.

=back

=item * 

Matt Trout's C<cat-install>

Available at L<http://www.shadowcat.co.uk/static/cat-install>, 
C<cat-install> can be a fairly painless way to get Catalyst up and 
running.  Just download the script from the link above and type C<perl 
cat-install>.  Depending on the speed of your Internet connection and 
your computer, it will probably take 30 to 60 minutes to install because 
it downloads, makes, compiles, and tests every module.  But this is an 
excellent way to automate the installation of all the latest modules 
used by Catalyst from CPAN.


=item * 

Other Possibilities

=over 4

=item *

OpenBSD Packages

The 2008 Advent Day 4 entry has more information on using OpenBSD 
packages to quickly build a system: 
L<http://www.catalystframework.org/calendar/2008/4>.

=item *

NetBSD Package Collection on Solaris

The 2008 Advent Day 15 entry has more information on using C<pkgsrc> and 
NetBSD packages on Solaris: 
L<http://www.catalystframework.org/calendar/2008/15>.

=item * 

CatInABox

You can get more information at 
L<http://www.catalystframework.org/calendar/2008/7>
or L<Perl::Dist::CatInABox|Perl::Dist::CatInABox>.

=item * 

Frank Speiser's Amazon EC2 Catalyst SDK

There are currently two flavors of publicly available Amazon Machine
Images (AMI) that include all the elements you'd need to begin
developing in a fully functional Catalyst environment within minutes.
See L<Catalyst::Manual::Installation|Catalyst::Manual::Installation>
for more details.

=back

=back

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


=head1 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.

B<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 C<.sql> files used to initialize the database
change between database systems: the Catalyst code generally remains the
same.


=head1 WHERE TO GET WORKING CODE

Each chapter of the tutorial has complete code available as a tarball in 
the main Catalyst Subversion repository (see the note at the beginning 
of each part for the appropriate svn command to use).

B<NOTE:> You can run the test cases for the final code through Chapter 8 
with the following commands:

	svn co http://dev.catalystframework.org/repos/Catalyst/trunk/examples/Tutorial/MyApp_Chapter8
	cd MyApp_Chapter8/MyApp
    CATALYST_DEBUG=0 prove -wl t

If you wish to include the L<HTML::FormFu|HTML::FormFu> section in your tests,
substitute C<MyApp_Chapter9_FormFu> for C<MyApp_Chapter8> in the URL
above (don't forget to "cd" out of the Ch8 directory if you ran the code above).

	svn co http://dev.catalystframework.org/repos/Catalyst/trunk/examples/Tutorial/MyApp_Chapter9_FormFu
	cd MyApp_Chapter9_FormFu/MyApp
    CATALYST_DEBUG=0 prove -wl t

You can also fire up the application under the development server that is conveniently
built in to Catalyst.  Just issue this command from the C<MyApp> directory where you
ran the test suite above:

    script/myapp_server.pl

And the application will start.  You can try out the application by 
pulling up C<http://localhost:3000> in your web browser (as mentioned 
earlier, change C<localhost> to a different IP address or DNS name if 
you are running your web browser and your Catalyst development on 
different boxes).  We will obviously see more about how to use the 
application as we go through the remaining chapters of the tutorial, but 
for now you can log in using the username "test01" and a password of 
"mypass".


=head1 AUTHOR

Kennedy Clark, C<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
L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.

Copyright 2006-2008, Kennedy Clark, under Creative Commons License
(L<http://creativecommons.org/licenses/by-sa/3.0/us/>).