=head1 DESCRIPTION
-In this chapter of the tutorial, we will create a very basic Catalyst
-web application, demonstrating a number of powerful capabilities, such
+In this chapter of the tutorial, we will create a very basic Catalyst
+web application, demonstrating a number of powerful capabilities, such
as:
=over 4
application. Given that many other documents cover this subject in
detail, MVC will not be discussed in depth here (for an excellent
introduction to MVC and general Catalyst concepts, please see
-L<Catalyst::Manual::About|Catalyst::Manual::About>). In short:
+L<Catalyst::Manual::About>). In short:
=over 4
The view takes model objects and renders them into something for the end
user to look at. Normally this involves a template-generation tool that
creates HTML for the user's web browser, but it could easily be code
-that generates other forms such as PDF documents, e-mails, spreadsheets,
+that generates other forms such as PDF documents, e-mails, spreadsheets,
or even "behind the scenes" formats such as XML and JSON.
=item * Controller
You can checkout the source code for this example from the catalyst
subversion repository as per the instructions in
-L<Catalyst::Manual::Tutorial::01_Intro|Catalyst::Manual::Tutorial::01_Intro>.
+L<Catalyst::Manual::Tutorial::01_Intro>.
=head1 CREATE A CATALYST PROJECT
-Catalyst provides a number of helper scripts that can be used to
-quickly flesh out the basic structure of your application. All
-Catalyst projects begin with the C<catalyst.pl> helper (see
-L<Catalyst::Helper|Catalyst::Helper> for more information on helpers).
-Also note that as of Catalyst 5.7000, you will not have the helper
-scripts unless you install both L<Catalyst::Runtime|Catalyst::Runtime>
-and L<Catalyst::Devel|Catalyst::Devel>.
+Catalyst provides a number of helper scripts that can be used to quickly
+flesh out the basic structure of your application. All Catalyst projects
+begin with the C<catalyst.pl> helper (see
+L<Catalyst::Helper> for more information on helpers).
+Also note that as of Catalyst 5.7000, you will not have the helper
+scripts unless you install both L<Catalyst::Runtime>
+and L<Catalyst::Devel>.
-In this first chapter of the tutorial, use the Catalyst C<catalyst.pl>
+In this first chapter of the tutorial, use the Catalyst C<catalyst.pl>
script to initialize the framework for an application called C<Hello>:
$ catalyst.pl Hello
03podcoverage.t
-Catalyst will "auto-discover" modules in the Controller, Model, and
-View directories. When you use the hello_create.pl script it will
-create Perl module scaffolds in those directories, plus test files in
-the "t" directory. The default location for templates is in the "root"
-directory. The scripts in the script directory will always start with
-the lowercased version of your application name. If your app is
-MaiTai, then the create script would be "maitai_create.pl".
-
-Though it's too early for any significant celebration, we already have
-a functioning application. We can use the Catalyst supplied script to
-start up a development server and view the default Catalyst page in
-your browser. All scripts in the script directory should be run from
-the base directory of your application, so change to the Hello
-directory.
-
-Run the following command to start up the built-in development web
-server (make sure you didn't forget the "C<cd Hello>" from the
-previous step):
-
-B<Note>: The "-r" argument enables reloading on code changes so you
-don't have to stop and start the server when you update code. See
-C<perldoc script/hello_server.pl> for additional options you might find
-helpful. Most of the rest of the tutorial will assume that you are using
-"-r" when you start the development server, but feel free to manually
-start and stop it (use C<Ctrl-C> to break out of the dev server) if you
-prefer.
+Catalyst will "auto-discover" modules in the Controller, Model, and View
+directories. When you use the C<hello_create.pl> script it will create Perl
+module scaffolds in those directories, plus test files in the "t"
+directory. The default location for templates is in the "root"
+directory. The scripts in the script directory will always start with
+the lowercased version of your application name. If your app is MaiTai,
+then the create script would be "maitai_create.pl".
+
+Though it's too early for any significant celebration, we already have a
+functioning application. We can use the Catalyst supplied script to
+start up a development server and view the default Catalyst page in your
+browser. All scripts in the script directory should be run from the base
+directory of your application, so change to the Hello directory.
+
+Run the following command to start up the built-in development web
+server (make sure you didn't forget the "C<cd Hello>" from the previous
+step):
+
+B<Note>: The "-r" argument enables reloading on code changes so you
+don't have to stop and start the server when you update code. See
+C<perldoc script/hello_server.pl> or C<script/hello_server.pl --help>
+for additional options you might find helpful. Most of the rest of the
+tutorial will assume that you are using "-r" when you start the
+development server, but feel free to manually start and stop it (use
+C<Ctrl-C> to breakout of the dev server) if you prefer.
$ script/hello_server.pl -r
[debug] Debug messages enabled
[debug] Statistics enabled
[debug] Loaded plugins:
.----------------------------------------------------------------------------.
- | Catalyst::Plugin::ConfigLoader 0.27 |
+ | Catalyst::Plugin::ConfigLoader 0.30 |
'----------------------------------------------------------------------------'
[debug] Loaded dispatcher "Catalyst::Dispatcher"
- [debug] Loaded engine "Catalyst::Engine::HTTP"
- [debug] Found home "/home/me/Hello"
- [debug] Loaded Config "/home/me/Hello/hello.conf"
+ [debug] Loaded engine "Catalyst::Engine"
+ [debug] Found home "/home/catalyst/Hello"
+ [debug] Loaded Config "/home/catalyst/Hello/hello.conf"
[debug] Loaded components:
.-----------------------------------------------------------------+----------.
| Class | Type |
| / | /default |
'-------------------------------------+--------------------------------------'
- [info] Hello powered by Catalyst 5.80020
- You can connect to your server at http://debian:3000
-
-Point your web browser to L<http://localhost:3000> (substituting a
-different hostname or IP address as appropriate) and you should be
-greeted by the Catalyst welcome screen (if you get some other welcome
-screen or an "Index" screen, you probably forgot to specify port 3000
-in your URL). Information similar to the following should be appended
-to the logging output of the development server:
-
- [info] *** Request 1 (0.001/s) [23194] [Sat Jan 16 11:09:18 2010] ***
- [debug] "GET" request for "/" from "127.0.0.1"
+ [info] Hello powered by Catalyst 5.90002
+ HTTP::Server::PSGI: Accepting connections at http://0:3000/
+
+Point your web browser to L<http://localhost:3000> (substituting a
+different hostname or IP address as appropriate) and you should be
+greeted by the Catalyst welcome screen (if you get some other welcome
+screen or an "Index" screen, you probably forgot to specify port 3000 in
+your URL). Information similar to the following should be appended to
+the logging output of the development server:
+
+ [info] Hello powered by Catalyst 5.90002
+ HTTP::Server::PSGI: Accepting connections at http://0:3000/
+ [info] *** Request 1 (0.067/s) [19026] [Tue Aug 30 17:24:32 2011] ***
+ [debug] "GET" request for "/" from "192.168.245.2"
[debug] Path is "/"
- [info] Request took 0.004851s (206.143/s)
+ [debug] Response Code: 200; Content-Type: text/html; charset=utf-8; Content-Length: 5613
+ [info] Request took 0.040895s (24.453/s)
.------------------------------------------------------------+-----------.
| Action | Time |
+------------------------------------------------------------+-----------+
- | /index | 0.000395s |
- | /end | 0.000425s |
+ | /index | 0.000916s |
+ | /end | 0.000877s |
'------------------------------------------------------------+-----------'
-B<Note>: Press C<Ctrl-C> to break out of the development server if
+B<Note>: Press C<Ctrl-C> to break out of the development server if
necessary.
=head2 The Simplest Way
-The Root.pm controller is a place to put global actions that usually
-execute on the root URL. Open the C<lib/Hello/Controller/Root.pm> file in
-your editor. You will see the "index" subroutine, which is
-responsible for displaying the welcome screen that you just saw in
-your browser.
+The Root.pm controller is a place to put global actions that usually
+execute on the root URL. Open the C<lib/Hello/Controller/Root.pm> file
+in your editor. You will see the "index" subroutine, which is
+responsible for displaying the welcome screen that you just saw in your
+browser.
sub index :Path :Args(0) {
my ( $self, $c ) = @_;
-
+
# Hello World
$c->response->body( $c->welcome_message );
}
-Later on you'll want to change that to something more reasonable, such
-as a "404" message or a redirect, but for now just leave it alone.
-
-The "C<$c>" here refers to the Catalyst context, which is used to
-access the Catalyst application. In addition to many other things,
-the Catalyst context provides access to "response" and "request"
-objects. (See L<Catalyst|Catalyst>,
-L<Catalyst::Response|Catalyst::Response>, and
-L<Catalyst::Request|Catalyst::Request>)
-
-C<$c-E<gt>response-E<gt>body> sets the HTTP response (see
-L<Catalyst::Response|Catalyst::Response>), while
-C<$c-E<gt>welcome_message> is a special method that returns the
-welcome message that you saw in your browser.
-
-The ":Path :Args(0)" after the method name are attributes which
-determine which URLs will be dispatched to this method. (You might see
-":Private" if you are using an older version of Catalyst, but using
-that with "default" or "index" is currently deprecated. If so, you
-should also probably upgrade before continuing the tutorial.)
-
-Some MVC frameworks handle dispatching in a central place. Catalyst,
-by policy, prefers to handle URL dispatching with attributes on
-controller methods. There is a lot of flexibility in specifying which
-URLs to match. This particular method will match all URLs, because it
-doesn't specify the path (nothing comes after "Path"), but will only
-accept a URL without any args because of the ":Args(0)".
-
-The default is to map URLs to controller names, and because of the way
-that Perl handles namespaces through package names, it is simple to
-create hierarchical structures in Catalyst. This means that you can
-create controllers with deeply nested actions in a clean and logical
-way. For example, the URL C<http://hello.com/admin/articles/create>
-maps to the package C<Hello::Controller::Admin::Articles>, and the
-C<create> method.
-
-Add the following subroutine to your C<lib/Hello/Controller/Root.pm>
-file:
+Later on you'll want to change that to something more reasonable, such
+as a "404" message or a redirect, but for now just leave it alone.
+
+The "C<$c>" here refers to the Catalyst context, which is used to access
+the Catalyst application. In addition to many other things, the Catalyst
+context provides access to "response" and "request" objects. (See
+L<Catalyst::Runtime>, L<Catalyst::Response>, and
+L<Catalyst::Request>)
+
+C<$c-E<gt>response-E<gt>body> sets the HTTP response (see
+L<Catalyst::Response>), while
+C<$c-E<gt>welcome_message> is a special method that returns the welcome
+message that you saw in your browser.
+
+The ":Path :Args(0)" after the method name are attributes which
+determine which URLs will be dispatched to this method. (You might see
+":Private" if you are using an older version of Catalyst, but using that
+with "default" or "index" is currently deprecated. If so, you should
+also probably upgrade before continuing the tutorial.)
+
+Some MVC frameworks handle dispatching in a central place. Catalyst, by
+policy, prefers to handle URL dispatching with attributes on controller
+methods. There is a lot of flexibility in specifying which URLs to
+match. This particular method will match all URLs, because it doesn't
+specify the path (nothing comes after "Path"), but will only accept a
+URL without any args because of the ":Args(0)".
+
+The default is to map URLs to controller names, and because of the way
+that Perl handles namespaces through package names, it is simple to
+create hierarchical structures in Catalyst. This means that you can
+create controllers with deeply nested actions in a clean and logical
+way. For example, the URL C<http://hello.com/admin/articles/create> maps
+to the package C<Hello::Controller::Admin::Articles>, and the C<create>
+method.
+
+While you leave the C<script/hello_server.pl -r> command running the
+development server in one window (don't forget the "-r" at the end!),
+open another window and add the following subroutine to your
+C<lib/Hello/Controller/Root.pm> file:
sub hello :Global {
my ( $self, $c ) = @_;
-
+
$c->response->body("Hello, World!");
}
B<TIP>: See Appendix 1 for tips on removing the leading spaces when
cutting and pasting example code from POD-based documents.
-Here you're sending your own string to the webpage.
-
-Save the file, and you should notice the following in your server output:
+Notice in the window running the Development Server that you should
+get output similar to the following:
Saw changes to the following files:
- - /home/me/Hello/lib/Hello/Controller/Root.pm (modify)
+ - /home/catalyst/Hello/lib/Hello/Controller/Root.pm (modify)
Attempting to restart the server
- ...
+ ...
[debug] Loaded Private actions:
.----------------------+--------------------------------------+--------------.
| Private | Class | Method |
| /index | Hello::Controller::Root | index |
| /hello | Hello::Controller::Root | hello |
'----------------------+--------------------------------------+--------------'
-
- [debug] Loaded Path actions:
- .-------------------------------------+--------------------------------------.
- | Path | Private |
- +-------------------------------------+--------------------------------------+
- | / | /index |
- | / | /default |
- | /hello | /hello |
- '-------------------------------------+--------------------------------------'
...
-Go to L<http://localhost:3000/hello> to see "Hello, World!". Also
-notice that the newly defined 'hello' action is listed under "Loaded
+The development server noticed the change in C<Hello::Controller::Root>
+and automatically restarted itself.
+
+Go to L<http://localhost:3000/hello> to see "Hello, World!". Also
+notice that the newly defined 'hello' action is listed under "Loaded
Private actions" in the development server debug output.
=head2 Hello, World! Using a View and a Template
-In the Catalyst world a "View" itself is not a page of XHTML or a
-template designed to present a page to a browser. Rather, it is the
-module that determines the I<type> of view -- HTML, pdf, XML, etc. For
-the thing that generates the I<content> of that view (such as the a
-Toolkit Template template file), the actual templates go under the
+In the Catalyst world a "View" itself is not a page of XHTML or a
+template designed to present a page to a browser. Rather, it is the
+module that determines the I<type> of view -- HTML, PDF, XML, etc. For
+the thing that generates the I<content> of that view (such as a
+Template Toolkit template file), the actual templates go under the
"root" directory.
To create a TT view, run:
- $ script/hello_create.pl view TT TT
+ $ script/hello_create.pl view HTML TT
-This creates the C<lib/Hello/View/TT.pm> module, which is a subclass of
-C<Catalyst::View::TT>.
+This creates the C<lib/Hello/View/HTML.pm> module, which is a subclass
+of C<Catalyst::View::TT>.
=over 4
=item *
-The first "TT" tells the script to name the View module "TT.pm", which is a
-commonly used name for TT views. (You can name it anything you want, such as
-"HTML.pm".)
+The first argument "HTML" tells the script to name the View module "HTML.pm",
+which is a commonly used name for TT views. You can name it anything you want,
+such as "MyView.pm". If you have more than one view, be sure to set the
+default_view in Hello.pm (See L<Catalyst::View::TT> for more
+details on setting this).
=item *
-The final "TT" tells Catalyst the I<type> of the view, with "TT"
-indicating that you want to a Template Toolkit view.
+The final "TT" tells Catalyst the I<type> of the view, with "TT"
+indicating that you want to use a Template Toolkit view.
=back
-If you look at C<lib/Hello/View/TT.pm> you will find that it only
+If you look at C<lib/Hello/View/HTML.pm> you will find that it only
contains a config statement to set the TT extension to ".tt".
-Now that the TT.pm "View" exists, Catalyst will autodiscover it and be
-able to use it to display the view templates using the "process"
-method that it inherits from the C<Catalyst::View::TT> class.
+Now that the HTML.pm "View" exists, Catalyst will autodiscover it and be
+able to use it to display the view templates using the "process" method
+that it inherits from the C<Catalyst::View::TT> class.
+
+Template Toolkit is a very full-featured template facility, with
+excellent documentation at L<http://template-toolkit.org/>, but since
+this is not a TT tutorial, we'll stick to only basic TT usage here (and
+explore some of the more common TT features in later chapters of the
+tutorial).
-Template Toolkit is a very full featured template facility, with
-excellent documentation at L<http://template-toolkit.org/>,
-but since this is not a TT tutorial, we'll stick to only basic TT
-usage here (and explore some of the more common TT features in later
-chapters of the tutorial).
+Create a C<root/hello.tt> template file (put it in the C<root> under the
+C<Hello> directory that is the base of your application). Here is a
+simple sample:
-Create a C<root/hello.tt> template file (put it in the C<root> under
-the C<Hello> directory that is the base of your application). Here is
-a simple sample:
-
<p>
This is a TT view template, called '[% template.name %]'.
</p>
-[% and %] are markers for the TT parts of the template. Inside you can
-access Perl variables and classes, and use TT directives. In this
-case, we're using a special TT variable that defines the name of the
-template file (C<hello.tt>). The rest of the template is normal HTML.
+[% and %] are markers for the TT parts of the template. Inside you can
+access Perl variables and classes, and use TT directives. In this case,
+we're using a special TT variable that defines the name of the template
+file (C<hello.tt>). The rest of the template is normal HTML.
-Change the hello method in C<lib/Hello/Controller/Root.pm> to the
+Change the hello method in C<lib/Hello/Controller/Root.pm> to the
following:
sub hello :Global {
my ( $self, $c ) = @_;
-
+
$c->stash(template => 'hello.tt');
}
-This time, instead of doing C<$c-E<gt>response-E<gt>body()>, you are
-setting the value of the "template" hash key in the Catalyst "stash",
-an area for putting information to share with other parts of your
-application. The "template" key determines which template will be
-displayed at the end of the request cycle. Catalyst controllers have a
-default "end" action for all methods which causes the first (or
-default) view to be rendered (unless there's a C<$c-E<gt>response-
-E<gt>body()> statement). So your template will be magically displayed
-at the end of your method.
+This time, instead of doing C<$c-E<gt>response-E<gt>body()>, you are
+setting the value of the "template" hash key in the Catalyst "stash", an
+area for putting information to share with other parts of your
+application. The "template" key determines which template will be
+displayed at the end of the request cycle. Catalyst controllers have a
+default "end" action for all methods which causes the first (or default)
+view to be rendered (unless there's a C<$c-E<gt>response-E<gt>body()>
+statement). So your template will be magically displayed at the end of
+your method.
After saving the file, the development server should automatically
-restart (again, the tutorial is written to assume that you are
-using the "-r" option -- manually restart it if you aren't),
-and look at L<http://localhost:3000/hello> in your again. You
-should see the template that you just made.
+restart (again, the tutorial is written to assume that you are using the
+"-r" option -- manually restart it if you aren't), and look at
+L<http://localhost:3000/hello> in your web browser again. You should see
+the template that you just created.
+
+B<TIP:> If you keep the server running with "-r" in a "background
+window," don't let that window get totally hidden... if you have a
+syntax error in your code, the debug server output will contain the
+error information.
+
+B<Note:> You will probably run into a variation of the "stash"
+statement above that looks like:
+
+ $c->stash->{template} = 'hello.tt';
+
+Although this style is still relatively common, the approach we
+used previous is becoming more common because it allows you to
+set multiple stash variables in one line. For example:
+
+ $c->stash(template => 'hello.tt', foo => 'bar',
+ another_thing => 1);
+
+You can also set multiple stash values with a hashref:
+
+ $c->stash({template => 'hello.tt', foo => 'bar',
+ another_thing => 1});
+
+Any of these formats work, but the C<$c-E<gt>stash(name =E<gt> value);>
+style is growing in popularity -- you may wish to use it all the time
+(even when you are only setting a single value).
=head1 CREATE A SIMPLE CONTROLLER AND AN ACTION
$ script/hello_create.pl controller Site
-This will create a C<lib/Hello/Controller/Site.pm> file (and a test
-file). Bring Site.pm up in your editor, and you can see that there's
-not much there.
+This will create a C<lib/Hello/Controller/Site.pm> file (and a test
+file). If you bring Site.pm up in your editor, you can see that
+there's not much there to see.
In C<lib/Hello/Controller/Site.pm>, add the following method:
my ( $self, $c ) = @_;
$c->stash(username => 'John',
- template => 'site/test.tt');
+ template => 'site/test.tt');
}
-Notice the "Local" attribute on the C<test> method. This will cause
-the C<test> action (now that we have assigned an "action type" to the
-method it appears as a "controller action" to Catalyst) to be executed
-on the "controller/method" URL, or, in this case, "site/test". We
-will see additional information on controller actions throughout the
-rest of the tutorial, but if you are curious take a look at
+Notice the "Local" attribute on the C<test> method. This will cause the
+C<test> action (now that we have assigned an "action type" to the method
+it appears as a "controller action" to Catalyst) to be executed on the
+"controller/method" URL, or, in this case, "site/test". We will see
+additional information on controller actions throughout the rest of the
+tutorial, but if you are curious take a look at
L<Catalyst::Manual::Intro/Actions>.
-It's not actually necessary to set the template value as we do here.
-By default TT will attempt to render a template that follows the
-naming pattern "controller/method.tt", and we're following that
-pattern here. However, in other situations you will need to specify
-the template (such as if you've "forwarded" to the method, or if it
-doesn't follow the default naming convention).
+It's not actually necessary to set the template value as we do here. By
+default TT will attempt to render a template that follows the naming
+pattern "controller/method.tt", and we're following that pattern here.
+However, in other situations you will need to specify the template (such
+as if you've "forwarded" to the method, or if it doesn't follow the
+default naming convention).
-We've also put the variable "username" into the stash, for use in the
+We've also put the variable "username" into the stash, for use in the
template.
-Make a subdirectory "site" in the "root" directory. Copy the hello.tt
-file into the directory as C<root/site/test.tt>, or create a new
-template file at that location. Include a line like:
+Make a subdirectory "site" in the "root" directory.
+
+ $ mkdir root/site
+
+Create a new template file in that directory named C<root/site/test.tt>
+and include a line like:
<p>Hello, [% username %]!</p>
-You should see your test.tt file displayed, including the name "John"
-that you set in the controller.
+Once the server automatically restarts, notice in the server output that
+C</site/test> is listed in the Loaded Path actions. Go to
+L<http://localhost:3000/site/test> in your browser and you should see
+your test.tt file displayed, including the name "John" that you set in
+the controller.
+
+
+You can jump to the next chapter of the tutorial here:
+L<More Catalyst Basics|Catalyst::Manual::Tutorial::03_MoreCatalystBasics>
-Once the server automatically restarts, notice in the server
-output that C</site/test> is listed in the Loaded Path actions.
-Go to L<http://localhost:3000/site/test> in your browser.
=head1 AUTHORS
Gerda Shank, C<gerda.shank@gmail.com>
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/>.
+Feel free to contact the author for any errors or suggestions, but the
+best way to report issues is via the CPAN RT Bug system at
+L<https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
-Copyright 2006-2008, Kennedy Clark & Gerda Shank, under Creative Commons License
+Copyright 2006-2011, Kennedy Clark, under the
+Creative Commons Attribution Share-Alike License Version 3.0
(L<http://creativecommons.org/licenses/by-sa/3.0/us/>).
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