environment where we can explore a variety of features used in virtually
all web applications.
-You can check out 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>.
+Source code for the tutorial in included in the F</home/catalyst/Final>
+directory of the Tutorial Virtual machine (one subdirectory per
+chapter). There are also instructions for downloading the code in
+L<Catalyst::Manual::Tutorial::01_Intro>.
Please take a look at
-L<Catalyst::Manual::Tutorial::01_Intro/CATALYST INSTALLATION> before
-doing the rest of this tutorial. Although the tutorial should work
-correctly under most any recent version of Perl running on any operating
-system, the tutorial has been written using Debian 5 and tested to be
-sure it runs correctly in this environment.
+L<Catalyst::Manual::Tutorial::01_Intro/STARTING WITH THE TUTORIAL VIRTUAL MACHINE>
+before doing the rest of this tutorial. Although the tutorial should
+work correctly under most any recent version of Perl running on any
+operating system, the tutorial has been written using the virtual
+machine that is available for download. The entire tutorial has been
+tested to be sure it runs correctly in this environment, so it is
+the most trouble-free way to get started with Catalyst.
=head1 CREATE A NEW APPLICATION
The remainder of the tutorial will build an application called C<MyApp>.
-First use the Catalyst C<catalyst.pl> script to initialize the framework
+First use the Catalyst F<catalyst.pl> script to initialize the framework
for the C<MyApp> application (make sure you aren't still inside the
directory of the C<Hello> application from the previous chapter of the
tutorial or in a directory that already has a "MyApp" subdirectory):
...
created "MyApp/script/myapp_create.pl"
Change to application directory and Run "perl Makefile.PL" to make sure your install is complete
+
+And change the "MyApp" directory the helper created:
+
$ cd MyApp
This creates a similar skeletal structure to what we saw in Chapter 2 of
=head1 EDIT THE LIST OF CATALYST PLUGINS
One of the greatest benefits of Catalyst is that it has such a large
-library of bases classes and plugins available that you can use easily
+library of base classes and plugins available that you can use to easily
add functionality to your application. Plugins are used to seamlessly
integrate existing Perl modules into the overall Catalyst framework. In
general, they do this by adding additional methods to the C<context>
object (generally written as C<$c>) that Catalyst passes to every
component throughout the framework.
-
+Take a look at the file F<lib/MyApp.pm> that the helper created above.
By default, Catalyst enables three plugins/flags:
=over 4
C<-Debug> Flag
Enables the Catalyst debug output you saw when we started the
-C<script/myapp_server.pl> development server earlier. You can remove
+F<script/myapp_server.pl> development server earlier. You can remove
this item when you place your application into production.
To be technically correct, it turns out that C<-Debug> is not a plugin,
-but a I<flag>. Although most of the items specified on the
-C<__PACKAGE__-E<gt>setup> line of your application class will be
-plugins, Catalyst supports a limited number of flag options (of these,
-C<-Debug> is the most common). See the documentation for C<Catalyst.pm>
-to get details on other flags (currently C<-Engine>, C<-Home>, and
-C<-Log>).
+but a I<flag>. Although most of the items specified on the C<use
+Catalyst> line of your application class will be plugins, Catalyst
+supports a limited number of flag options (of these, C<-Debug> is the
+most common). See the documentation for
+L<https://metacpan.org/module/Catalyst|Catalyst.pm> to get details on
+other flags (currently C<-Engine>, C<-Home>, C<-Log>, and C<-Stats>).
If you prefer, there are several other ways to enable debug output:
=item *
-Use the C<$c-E<gt>debug> method
+the C<< $c->debug >> method on the C<$c> Catalyst context object
=item *
-The C<-d> option to C<script/myapp_server.pl>
+the C<-d> option on the F<script/myapp_server.pl> script
=item *
-The C<CATALYST_DEBUG=1> environment variable (or set it to
-zero to temporarily disable debug output).
+the C<CATALYST_DEBUG=1> environment variable (or C<CATALYST_DEBUG=0>
+to temporarily disable debug output)
=back
B<TIP>: Depending on your needs, it can be helpful to permanently remove
C<-Debug> from C<lib/MyApp.pm> and then use the C<-d> option to
-C<script/myapp_server.pl> to re-enable it just for the development
-server. We will not be using that approach in the tutorial, but feel
-free to make use of it in your own projects.
+F<script/myapp_server.pl> to re-enable it when needed. We will not be
+using that approach in the tutorial, but feel free to make use of it in
+your own projects.
=item *
-L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader>
+L<Catalyst::Plugin::ConfigLoader>
C<ConfigLoader> provides an automatic way to load configurable
parameters for your application from a central
-L<Config::General|Config::General> file (versus having the values
+L<Config::General> file (versus having the values
hard-coded inside your Perl modules). Config::General uses syntax very
similar to Apache configuration files. We will see how to use this
feature of Catalyst during the authentication and authorization sections
-(Chapter 5 and Chapter 6).
+(L<Chapter 5|Catalyst::Manual::Tutorial::05_Authentication> and
+L<Chapter 6|Catalyst::Manual::Tutorial::06_Authorization>).
B<IMPORTANT NOTE:> If you are using a version of
-L<Catalyst::Devel|Catalyst::Devel> prior to version 1.06, be aware that
+L<Catalyst::Devel> prior to version 1.06, be aware that
Catalyst changed the default format from YAML to the more
straightforward C<Config::General> style. This tutorial uses the newer
C<myapp.conf> file for C<Config::General>. However, Catalyst supports
-both formats and will automatically use either C<myapp.conf> or
-C<myapp.yml> (or any other format supported by
-L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> and
-L<Config::Any|Config::Any>). If you are using a version of
+both formats and will automatically use either F<myapp.conf> or
+F<myapp.yml> (or any other format supported by
+L<Catalyst::Plugin::ConfigLoader> and
+L<Config::Any>). If you are using a version of
Catalyst::Devel prior to 1.06, you can convert to the newer format by
-simply creating the C<myapp.conf> file manually and deleting
-C<myapp.yml>. The default contents of the C<myapp.conf> you create
+simply creating the F<myapp.conf> file manually and deleting
+F<myapp.yml>. The default contents of the F<myapp.conf> you create
should only consist of one line:
name MyApp
=item *
-L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple>
+L<Catalyst::Plugin::Static::Simple>
C<Static::Simple> provides an easy way to serve static content, such as
images and CSS files, from the development server.
=back
-For our application, we want to add one new plugin into the mix. To do
-this, edit C<lib/MyApp.pm> (this file is generally referred to as your
+For our application, we want to add one new plugin to the mix. To do
+this, edit F<lib/MyApp.pm> (this file is generally referred to as your
I<application class>) and delete the lines with:
use Catalyst qw/
-Debug
ConfigLoader
Static::Simple
-
+
StackTrace
/;
result.
This tells Catalyst to start using one additional plugin,
-L<Catalyst::Plugin::StackTrace>, to add a stack trace to the standard
-Catalyst "debug screen" (the screen Catalyst sends to your browser when
-an error occurs). Be aware that
+L<Catalyst::Plugin::StackTrace>, to add a stack trace near the top of
+the standard Catalyst "debug screen" (the screen Catalyst sends to your
+browser when an error occurs). Be aware that
L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your
browser, not in the console window from which you're running your
application, which is where logging output usually goes.
=item *
C<__PACKAGE__> is just a shorthand way of referencing the name of the
-package where it is used. Therefore, in C<MyApp.pm>, C<__PACKAGE__> is
+package where it is used. Therefore, in F<MyApp.pm>, C<__PACKAGE__> is
equivalent to C<MyApp>.
=item *
name. Additionally, you can spread the plugin names across multiple
lines as shown here or place them all on one line.
+=item *
+
+If you want to see what the StackTrace error screen looks like, edit
+F<lib/MyApp/Controller/Root.pm> and put a C<die "Oops";> command in the
+C<sub index :Path :Args(0)> method. Then start the development server
+and open C<http://localhost:3000/> in your browser. You should get a
+screen that starts with "Caught exception in
+MyApp::Controller::Root->index" with sections showing a stacktrace,
+information about the Request and Response objects, the stash (something
+we will learn about soon), and the applications configuration.
+B<Just don't forget to remove the die before you continue the tutorial!>
+:-)
+
=back
actions:
$ script/myapp_create.pl controller Books
- exists "/home/me/MyApp/script/../lib/MyApp/Controller"
- exists "/home/me/MyApp/script/../t"
- created "/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm"
- created "/home/me/MyApp/script/../t/controller_Books.t"
-
-Then edit C<lib/MyApp/Controller/Books.pm> (as discussed in Chapter 2 of
-the Tutorial, Catalyst has a separate directory under C<lib/MyApp> for
-each of the three parts of MVC: C<Model>, C<View>, and C<Controller>)
+ exists "/home/catalyst/MyApp/script/../lib/MyApp/Controller"
+ exists "/home/catalyst/MyApp/script/../t"
+ created "/home/catalyst/MyApp/script/../lib/MyApp/Controller/Books.pm"
+ created "/home/catalyst/MyApp/script/../t/controller_Books.t"
+
+Then edit F<lib/MyApp/Controller/Books.pm> (as discussed in
+L<Chapter 2|Catalyst::Manual::Tutorial::02_CatalystBasics> of
+the Tutorial, Catalyst has a separate directory under F<lib/MyApp> for
+each of the three parts of MVC: C<Model>, C<View> and C<Controller>)
and add the following method to the controller:
=head2 list
-
+
Fetch all book objects and pass to books/list.tt2 in stash to be displayed
-
+
=cut
-
+
sub list :Local {
# Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
# 'Context' that's used to 'glue together' the various components
# that make up the application
my ($self, $c) = @_;
-
+
# Retrieve all of the book records as book model objects and store in the
# stash where they can be accessed by the TT template
# $c->stash(books => [$c->model('DB::Book')->all]);
# But, for now, use this code until we create the model later
$c->stash(books => '');
-
+
# Set the TT template to use. You will almost always want to do this
# in your action methods (action methods respond to user input in
# your controllers).
$c->stash(template => 'books/list.tt2');
}
-B<TIP>: See Appendix 1 for tips on removing the leading spaces when
-cutting and pasting example code from POD-based documents.
+B<TIP>: See L<Appendix 1|Catalyst::Manual::Tutorial::10_Appendices> for
+tips on removing the leading spaces when cutting and pasting example
+code from POD-based documents.
Programmers experienced with object-oriented Perl should recognize
C<$self> as a reference to the object where this method was called. On
the other hand, C<$c> will be new to many Perl programmers who have not
-used Catalyst before (it's sometimes written as C<$context>). The
-Context object is automatically passed to all Catalyst components. It
-is used to pass information between components and provide access to
-Catalyst and plugin functionality.
-
-Catalyst actions are regular Perl methods, but they make use of
-attributes (the "C<:Local>" next to the "C<sub list>" in the code above)
-to provide additional information to the Catalyst dispatcher logic (note
-that the space between the colon and the attribute name is optional; you
-will see attributes written both ways). Most Catalyst Controllers use
-one of five action types:
+used Catalyst before. This is the "Catalyst Context object", and it is
+automatically passed as the second argument to all Catalyst action
+methods. It is used to pass information between components and provide
+access to Catalyst and plugin functionality.
+
+Catalyst Controller actions are regular Perl methods, but they make use
+of attributes (the "C<:Local>" next to the "C<sub list>" in the code
+above) to provide additional information to the Catalyst dispatcher
+logic (note that there can be an optional space between the colon and
+the attribute name; you will see attributes written both ways). Most
+Catalyst Controllers use one of five action types:
=over 4
=item *
B<:Private> -- Use C<:Private> for methods that you want to make into an
-action, but you do not want Catalyst to directly expose the method to
+action, but you do not want Catalyst to directly expose the method to
your users. Catalyst will not map C<:Private> methods to a URI. Use
them for various sorts of "special" methods (the C<begin>, C<auto>, etc.
discussed below) or for methods you want to be able to C<forward> or
-C<detach> to. (If the method is a plain old "helper method" that you
+C<detach> to. (If the method is a "plain old method" that you
don't want to be an action at all, then just define the method without
any attribute -- you can call it in your code, but the Catalyst
-dispatcher will ignore it.)
+dispatcher will ignore it. You will also have to manually include
+C<$c> if you want access to the context object in the method vs. having
+Catalyst automatically include C<$c> in the argument list for you
+if it's a full-fledged action.)
There are five types of "special" built-in C<:Private> actions:
C<begin>, C<end>, C<default>, C<index>, and C<auto>.
B<:Path> -- C<:Path> actions let you map a method to an explicit URI
path. For example, "C<:Path('list')>" in
-C<lib/MyApp/Controller/Books.pm> would match on the URL
+F<lib/MyApp/Controller/Books.pm> would match on the URL
C<http://localhost:3000/books/list>, but "C<:Path('/list')>" would match
on C<http://localhost:3000/list> (because of the leading slash). You
can use C<:Args()> to specify how many arguments an action should
-accept. See L<Catalyst::Manual::Intro/Action_types> for more
+accept. See L<Catalyst::Manual::Intro/Action-types> for more
information and examples.
=item *
B<:Local> -- C<:Local> is merely a shorthand for
"C<:Path('_name_of_method_')>". For example, these are equivalent:
-"C<sub create_book :Local {...}>" and "C<sub create_book
-:Path('create_book') {...}>".
+"C<sub create_book :Local {...}>" and
+"C<sub create_book :Path('create_book') {...}>".
=item *
B<:Chained> -- Newer Catalyst applications tend to use the Chained
dispatch form of action types because of its power and flexibility. It
-allows a series of controller methods to be automatically dispatched to
-service a single user request. See
-L<Catalyst::Manual::Tutorial::04_BasicCRUD|Catalyst::Manual::Tutorial::04_BasicCRUD>
-and L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained>
-for more information on chained actions.
+allows a series of controller methods to be automatically dispatched
+when servicing a single user request. See
+L<Catalyst::Manual::Tutorial::04_BasicCRUD> and
+L<Catalyst::DispatchType::Chained> for more information on chained
+actions.
=back
-You should refer to L<Catalyst::Manual::Intro/Action_types> for
+You should refer to L<Catalyst::Manual::Intro/Action-types> for
additional information and for coverage of some lesser-used action types
not discussed here (C<Regex> and C<LocalRegex>).
=head1 CATALYST VIEWS
-As mentioned in Chapter 2 of the tutorial, views are where you render
-output, typically for display in the user's web browser (but also
-possibly using into output-generation systems, such as PDF or JSON).
-The code in C<lib/MyApp/View> selects the I<type> of view to use, with
-the actual rendering template found in the C<root> directory. As with
-virtually every aspect of Catalyst, options abound when it comes to the
-specific view technology you adopt inside your application. However,
-most Catalyst applications use the Template Toolkit, known as TT (for
-more information on TT, see L<http://www.template-toolkit.org>). Other
-somewhat popular view technologies include Mason
-(L<http://www.masonhq.com> and L<http://www.masonbook.com>) and
-L<HTML::Template> (L<http://html-template.sourceforge.net>).
+As mentioned in L<Chapter 2|Catalyst::Manual::Tutorial::02_CatalystBasics>
+of the tutorial, views are where you render output, typically for
+display in the user's web browser (but can generate other types of
+output such as PDF or JSON). The code in F<lib/MyApp/View> selects the
+I<type> of view to use, with the actual rendering template found in the
+C<root> directory. As with virtually every aspect of Catalyst, options
+abound when it comes to the specific view technology you adopt inside
+your application. However, most Catalyst applications use the Template
+Toolkit, known as TT (for more information on TT, see
+L<http://www.template-toolkit.org>). Other somewhat popular view
+technologies include Mason (L<http://www.masonhq.com> and
+L<http://www.masonbook.com>) and L<HTML::Template>
+(L<http://html-template.sourceforge.net>).
=head2 Create a Catalyst View
When using TT for the Catalyst view, the main helper script is
-L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT>. You may also
-come across references to
-L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite>, but
-its use is now deprecated.
+L<Catalyst::Helper::View::TT>. You may also come across references to
+L<Catalyst::Helper::View::TTSite>, but its use is now deprecated.
-Enter the following command to enable the C<TT> style of view rendering
-for this tutorial:
+For our book application, enter the following command to enable the
+C<TT> style of view rendering:
$ script/myapp_create.pl view HTML TT
- exists "/home/me/MyApp/script/../lib/MyApp/View"
- exists "/home/me/MyApp/script/../t"
- created "/home/me/MyApp/script/../lib/MyApp/View/HTML.pm"
- created "/home/me/MyApp/script/../t/view_HTML.t"
-
-This simply creates a view called C<HTML> in a file called C<HTML.pm>
-(the first argument). It is now up to you to decide how you want to
-structure your view layout. For the tutorial, we will start with a very
-simple TT template to initially demonstrate the concepts, but quickly
-migrate to a more typical "wrapper page" type of configuration (where
-the "wrapper" controls the overall "look and feel" of your site from a
-single file or set of files).
-
-Edit C<lib/MyApp/View/HTML.pm> and you should see something similar to
+ exists "/home/catalyst/MyApp/script/../lib/MyApp/View"
+ exists "/home/catalyst/MyApp/script/../t"
+ created "/home/catalyst/MyApp/script/../lib/MyApp/View/HTML.pm"
+ created "/home/catalyst/MyApp/script/../t/view_HTML.t"
+
+This creates a view called C<HTML> (the first argument) in a file called
+C<HTML.pm> that uses L<Catalyst::View::TT> (the second argument) as the
+"rendering engine".
+
+It is now up to you to decide how you want to structure your view
+layout. For the tutorial, we will start with a very simple TT template
+to initially demonstrate the concepts, but quickly migrate to a more
+typical "wrapper page" type of configuration (where the "wrapper"
+controls the overall "look and feel" of your site from a single file or
+set of files).
+
+Edit F<lib/MyApp/View/HTML.pm> and you should see something similar to
the following:
__PACKAGE__->config(
'.tt2'.
You can also configure components in your application class. For
-example, Edit C<lib/MyApp.pm> and you should see that the default:
+example, Edit F<lib/MyApp.pm> and you should see the default
+configuration above the call to C<< _PACKAGE__->setup >> (your defaults
+could be different depending on the version of Catalyst you are using):
+
+ __PACKAGE__->config(
+ name => 'MyApp',
+ # Disable deprecated behavior needed by old applications
+ disable_component_resolution_regex_fallback => 1,
+ );
- __PACKAGE__->setup;
-Above this, add config:
+Change this to match the following (insert a new
+C<< __PACKAGE__->config >> below the existing statement):
__PACKAGE__->config(
+ name => 'MyApp',
+ # Disable deprecated behavior needed by old applications
+ disable_component_resolution_regex_fallback => 1,
+ );
+ __PACKAGE__->config(
+ # Configure the view
'View::HTML' => {
#Set the location for TT files
INCLUDE_PATH => [
],
},
);
- # This line was here already
- __PACKAGE__->setup;
This changes the base directory for your template files from C<root> to
-C<root/src>.
-
-The reason to do this outside the C<lib/MyApp/View/HTML.pm> file is that
-the template path is found with the C<path_to> method, to get a path
-relative to the application root (no matter where it is installed), but
-this requires the application to be loaded...
-
-Trying to set this setting in the view means that you have a chicken and
-egg problem, in that the view requires the application to be loaded, but
-loading the application loads the view.
-
-Putting the configuration which depends on the application class into
-that class is the neatest way to avoid this issue.
+F<root/src>.
Please stick with the settings above for the duration of the tutorial,
but feel free to use whatever options you desire in your applications
-(as with most things Perl, there's more than one way to do it...).
+(as with most things in Perl, there's more than one way to do it...).
-B<Note:> We will use C<root/src> as the base directory for our template
+B<Note:> We will use F<root/src> as the base directory for our template
files, with a full naming convention of
-C<root/src/_controller_name_/_action_name_.tt2>. Another popular option
-is to use C<root/> as the base (with a full filename pattern of
-C<root/_controller_name_/_action_name_.tt2>).
+F<root/src/_controller_name_/_action_name_.tt2>. Another popular option
+is to use F<root/> as the base (with a full filename pattern of
+F<root/_controller_name_/_action_name_.tt2>).
=head2 Create a TT Template Page
$ mkdir -p root/src/books
-Then create C<root/src/books/list.tt2> in your editor and enter:
+Then create F<root/src/books/list.tt2> in your editor and enter:
+
+ [% # This is a TT comment. -%]
- [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%]
- [% # see this "chomping" in your browser because HTML ignores blank lines, but -%]
- [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%]
- [%- # optional, but both the beginning and the ending TT tags support chomping. -%]
-
- [% # Provide a title -%]
+ [%- # Provide a title -%]
[% META title = 'Book List' -%]
-
+
+ [% # Note That the '-' at the beginning or end of TT code -%]
+ [% # "chomps" the whitespace/newline at that end of the -%]
+ [% # output (use View Source in browser to see the effect) -%]
+
+ [% # Some basic HTML with a loop to display books -%]
<table>
<tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr>
[% # Display each book in a table row %]
As indicated by the inline comments above, the C<META title> line uses
TT's META feature to provide a title to the "wrapper" that we will
-create later. Meanwhile, the C<FOREACH> loop iterates through each
-C<book> model object and prints the C<title> and C<rating> fields.
+create later (and essentially does nothing at the moment). Meanwhile,
+the C<FOREACH> loop iterates through each C<book> model object and
+prints the C<title> and C<rating> fields.
The C<[%> and C<%]> tags are used to delimit Template Toolkit code. TT
supports a wide variety of directives for "calling" other files,
looping, conditional logic, etc. In general, TT simplifies the usual
range of Perl operators down to the single dot (".") operator. This
applies to operations as diverse as method calls, hash lookups, and list
-index values (see
-L<https://metacpan.org/module/Template::Manual::Variables> for details
-and examples). In addition to the usual L<Template> module Pod
+index values (see L<Template::Manual::Variables> for details and
+examples). In addition to the usual L<Template::Toolkit> module Pod
documentation, you can access the TT manual at
L<https://metacpan.org/module/Template::Manual>.
methods in your model that abstract out a set of code into a single call
from your TT template. (Note that the same is true of your controller
logic as well -- complex sections of code in your controllers should
-often be pulled out and placed into your model objects.) In Chapter 4
-of the tutorial we will explore some extremely helpful and powerful
-features of L<DBIx::Class> that allow you to pull code out of your views
-and controllers and place it where it rightfully belongs in a model
-class.
+often be pulled out and placed into your model objects.) In
+L<Chapter 4|Catalyst::Manual::Tutorial::04_BasicCRUD> of the tutorial we
+will explore some extremely helpful and powerful features of
+L<DBIx::Class> that allow you to pull code out of your views and
+controllers and place it where it rightfully belongs in a model class.
=head2 Test Run The Application
In this step, we make a text file with the required SQL commands to
create a database table and load some sample data. We will use SQLite
(L<http://www.sqlite.org>), a popular database that is lightweight and
-easy to use. Be sure to get at least version 3. Open C<myapp01.sql> in
+easy to use. Be sure to get at least version 3. Open F<myapp01.sql> in
your editor and enter:
--
INSERT INTO book_author VALUES (4, 7);
INSERT INTO book_author VALUES (5, 8);
-Then use the following command to build a C<myapp.db> SQLite database:
+Then use the following command to build a F<myapp.db> SQLite database:
$ sqlite3 myapp.db < myapp01.sql
If you need to create the database more than once, you probably want to
issue the C<rm myapp.db> command to delete the database before you use
-the C<sqlite3 myapp.db E<lt> myapp01.sql> command.
+the C<< sqlite3 myapp.db < myapp01.sql >> command.
-Once the C<myapp.db> database file has been created and initialized, you
+Once the F<myapp.db> database file has been created and initialized, you
can use the SQLite command line environment to do a quick dump of the
database contents:
$ sqlite3 myapp.db
- SQLite version 3.6.22
+ SQLite version 3.7.3
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> select * from book;
=head1 DATABASE ACCESS WITH DBIx::Class
Catalyst can be used with virtually any form of datastore available via
-Perl. For example, L<Catalyst::Model::DBI|Catalyst::Model::DBI> can be
-used to access databases through the traditional Perl L<DBI> interface
-or you can use a model to access files of any type on the filesystem.
-However, most Catalyst applications use some form of object-relational
-mapping (ORM) technology to create objects associated with tables in a
-relational database. Matt Trout's L<DBIx::Class|DBIx::Class>
-(abbreviated as "DBIC") has rapidly emerged as the Perl-based ORM
-technology of choice. Most new Catalyst applications rely on
-DBIx::Class, as will this tutorial.
+Perl. For example, L<Catalyst::Model::DBI> can be used to access
+databases through the traditional Perl L<DBI> interface or you can use a
+model to access files of any type on the filesystem. However, most
+Catalyst applications use some form of object-relational mapping (ORM)
+technology to create objects associated with tables in a relational
+database, and Matt Trout's L<DBIx::Class> (abbreviated as "DBIC") is the
+usual choice (this tutorial will use L<DBIx::Class>).
Although DBIx::Class has included support for a C<create=dynamic> mode
to automatically read the database structure every time the application
"flashy" demos, the use of the C<create=static> mode we use below can be
implemented just as quickly and provides many advantages (such as the
ability to add your own methods to the overall DBIC framework, a
-technique that we see in Chapter 4).
-
-
-=head2 Make Sure You Have a Recent Version of the DBIx::Class Model
-
-First, let's be sure we have a recent version of the DBIC helper,
-L<Catalyst::Model::DBIC::Schema>, so that we can take advantage of some
-recent enhancements in how foreign keys are handled with SQLite. To
-check your version, run this command:
-
- $ perl -MCatalyst::Model::DBIC::Schema -e \
- 'print "$Catalyst::Model::DBIC::Schema::VERSION\n"'
- 0.4
-
-Please note the '\' above. Depending on your environment, you might be
-able to cut and paste the text as shown or need to remove the '\'
-character to that the command is all on a single line.
-
-If you are following along in Debian 5, you should have version 0.40 or
-higher (shown above as "0.4" with the tailing zero removed). If you have
-less than v0.39, you will need to run this command to install it
-directly from CPAN:
-
- $ cpan -i Catalyst::Model::DBIC::Schema
+technique that we see in
+L<Chapter 4|Catalyst::Manual::Tutorial::04_BasicCRUD>).
-And re-run the version print command to verify that you are now at 0.39
-or higher.
-In addition, since we are using SQLite's foreign key support here,
-please be sure that you use version C<1.27> of L<DBD::SQLite> or later:
-
- $ perl -MDBD::SQLite -e 'print "$DBD::SQLite::VERSION\n"'
- 1.29
+=head2 Create Static DBIx::Class Schema Files
-Upgrade if you are not at version C<1.27> or higher.
+B<Note:> If you are not following along in the Tutorial Virtual Machine,
+please be sure that you have version 1.27 or higher of DBD::SQLite and
+version 0.39 or higher of Catalyst::Model::DBIC::Schema. (The Tutorial
+VM already has versions that are known to work.) You can get your
+currently installed version numbers with the following commands.
-Also, remember to put a line requiring the version of the module you
-just installed into your Makefile.PL
+ $ perl -MCatalyst::Model::DBIC::Schema\ 999
+ $ perl -MDBD::SQLite\ 999
-=head2 Create Static DBIx::Class Schema Files
-
-Before you continue, make sure your C<myapp.db> database file is in the
+Before you continue, make sure your F<myapp.db> database file is in the
application's topmost directory. Now use the model helper with the
C<create=static> option to read the database with
-L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> and
+L<DBIx::Class::Schema::Loader> and
automatically build the required files for us:
$ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
create=static dbi:SQLite:myapp.db \
on_connect_do="PRAGMA foreign_keys = ON"
- exists "/home/me/MyApp/script/../lib/MyApp/Model"
- exists "/home/me/MyApp/script/../t"
- Dumping manual schema for MyApp::Schema to directory /home/me/MyApp/script/../lib ...
+ exists "/home/catalyst/MyApp/script/../lib/MyApp/Model"
+ exists "/home/catalyst/MyApp/script/../t"
+ Dumping manual schema for MyApp::Schema to directory /home/catalyst/MyApp/script/../lib ...
Schema dump completed.
- created "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm"
- created "/home/me/MyApp/script/../t/model_DB.t"
+ created "/home/catalyst/MyApp/script/../lib/MyApp/Model/DB.pm"
+ created "/home/catalyst/MyApp/script/../t/model_DB.t"
Please note the '\' above. Depending on your environment, you might be
able to cut and paste the text as shown or need to remove the '\'
character to that the command is all on a single line.
-The C<script/myapp_create.pl> command breaks down like this:
+The F<script/myapp_create.pl> command breaks down like this:
=over 4
=item *
C<DB> is the name of the model class to be created by the helper in
-C<lib/MyApp/Model>.
+the F<lib/MyApp/Model> directory.
=item *
-C<DBIC::Schema> is the type of the model to create.
+C<DBIC::Schema> is the type of the model to create. This equates to
+L<Catalyst::Model::DBIC::Schema>, the standard way to use a DBIC-based
+model inside of Catalyst.
=item *
C<MyApp::Schema> is the name of the DBIC schema file written to
-C<lib/MyApp/Schema.pm>.
+F<lib/MyApp/Schema.pm>.
=item *
-C<create=static> causes
-L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to load the
-schema as it runs and then write that information out into files.
+C<create=static> causes L<DBIx::Class::Schema::Loader> to load the
+schema as it runs and then write that information out into
+F<lib/MyApp/Schema.pm> and files under the F<lib/MyApp/Schema>
+directory.
=item *
=item *
And finally, the C<on_connect_do> string requests that
-L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> create
+L<DBIx::Class::Schema::Loader> create
foreign key relationships for us (this is not needed for databases such
as PostgreSQL and MySQL, but is required for SQLite). If you take a look
-at C<lib/MyApp/Model/DB.pm>, you will see that the SQLite pragma is
-propogated to the Model, so that SQLite's recent (and optional) foreign
+at F<lib/MyApp/Model/DB.pm>, you will see that the SQLite pragma is
+propagated to the Model, so that SQLite's recent (and optional) foreign
key enforcement is enabled at the start of every database connection.
-
=back
-If you look in the C<lib/MyApp/Schema.pm> file, you will find that it
+
+If you look in the F<lib/MyApp/Schema.pm> file, you will find that it
only contains a call to the C<load_namespaces> method. You will also
-find that C<lib/MyApp> contains a C<Schema> subdirectory, which then has
+find that F<lib/MyApp> contains a C<Schema> subdirectory, which then has
a subdirectory called "Result". This "Result" subdirectory then has
files named according to each of the tables in our simple database
-(C<Author.pm>, C<BookAuthor.pm>, and C<Book.pm>). These three files are
-called "Result Classes" in DBIx::Class nomenclature. Although the Result
-Class files are named after tables in our database, the classes
-correspond to the I<row-level data> that is returned by DBIC (more on
-this later, especially in
+(F<Author.pm>, F<BookAuthor.pm>, and F<Book.pm>). These three files are
+called "Result Classes" (or
+"L<ResultSource Classes|DBIx::Class::ResultSource>") in DBIx::Class
+nomenclature. Although the Result Class files are named after tables in
+our database, the classes correspond to the I<row-level data> that is
+returned by DBIC (more on this later, especially in
L<Catalyst::Manual::Tutorial::04_BasicCRUD/EXPLORING THE POWER OF DBIC>).
The idea with the Result Source files created under
-C<lib/MyApp/Schema/Result> by the C<create=static> option is to only
+F<lib/MyApp/Schema/Result> by the C<create=static> option is to only
edit the files below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!>
warning. If you place all of your changes below that point in the file,
you can regenerate the automatically created information at the top of
Also note the "flow" of the model information across the various files
and directories. Catalyst will initially load the model from
-C<lib/MyApp/Model/DB.pm>. This file contains a reference to
-C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, the call
+F<lib/MyApp/Model/DB.pm>. This file contains a reference to
+F<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, the call
to C<load_namespaces> in C<Schema.pm> will load each of the "Result
-Class" files from the C<lib/MyApp/Schema/Result> subdirectory. The
+Class" files from the F<lib/MyApp/Schema/Result> subdirectory. The
final outcome is that Catalyst will dynamically create three
table-specific Catalyst models every time the application starts (you
can see these three model files listed in the debug output generated
when you launch the application).
+Additionally, the F<lib/MyApp/Schema.pm> model can easily be loaded
+outside of Catalyst, for example, in command-line utilities and/or cron
+jobs. F<lib/MyApp/Model/DB.pm> provides a very thin "bridge" between
+Catalyst and this external database model. Once you see how we can
+add some powerful features to our DBIC model in
+L<Chapter 4|Catalyst::Manual::Tutorial::04_BasicCRUD>, the elegance
+of this approach will start to become more obvious.
+
B<NOTE:> Older versions of
-L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> use the
+L<Catalyst::Model::DBIC::Schema> use the
deprecated DBIx::Class C<load_classes> technique instead of the newer
C<load_namespaces>. For new applications, please try to use
C<load_namespaces> since it more easily supports a very useful DBIC
=head1 ENABLE THE MODEL IN THE CONTROLLER
-Open C<lib/MyApp/Controller/Books.pm> and un-comment the model code we
-left disabled earlier so that your version matches the following (un-
-comment the line containing C<[$c-E<gt>model('DB::Book')-E<gt>all]> and
-delete the next 2 lines):
+Open F<lib/MyApp/Controller/Books.pm> and un-comment the model code we
+left disabled earlier so that your version matches the following
+(un-comment the line containing C<< [$c->model('DB::Book')->all] >>
+and delete the next 2 lines):
=head2 list
-
+
Fetch all book objects and pass to books/list.tt2 in stash to be displayed
-
+
=cut
-
+
sub list :Local {
# Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
# 'Context' that's used to 'glue together' the various components
# that make up the application
my ($self, $c) = @_;
-
+
# Retrieve all of the book records as book model objects and store
# in the stash where they can be accessed by the TT template
$c->stash(books => [$c->model('DB::Book')->all]);
-
+
# Set the TT template to use. You will almost always want to do this
# in your action methods (action methods respond to user input in
# your controllers).
$c->stash(template => 'books/list.tt2');
}
-B<TIP>: You may see the C<$c-E<gt>model('DB::Book')> un-commented above
-written as C<$c-E<gt>model('DB')-E<gt>resultset('Book')>. The two are
-equivalent. Either way, C<$c-E<gt>model> returns a
-L<DBIx::Class::ResultSet|DBIx::Class::ResultSet> which handles queries
+B<TIP>: You may see the C<< $c->model('DB::Book') >> un-commented above
+written as C<< $c->model('DB')->resultset('Book') >>. The two are
+equivalent. Either way, C<< $c->model >> returns a
+L<DBIx::Class::ResultSet> which handles queries
against the database and iterating over the set of results that is
returned.
-We are using the C<-E<gt>all> to fetch all of the books. DBIC supports
+We are using the C<< ->all >> to fetch all of the books. DBIC supports
a wide variety of more advanced operations to easily do things like
filtering and sorting the results. For example, the following could be
used to sort the results by descending title:
Some other examples are provided in
L<DBIx::Class::Manual::Cookbook/Complex WHERE clauses>, with additional
information found at L<DBIx::Class::ResultSet/search>,
-L<DBIx::Class::Manual::FAQ/Searching>,
-L<DBIx::Class::Manual::Intro|DBIx::Class::Manual::Intro> and
-L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>.
+L<DBIx::Class::Manual::FAQ/Searching>, L<DBIx::Class::Manual::Intro> and
+L<Catalyst::Model::DBIC::Schema>.
=head2 Test Run The Application
-First, let's enable an environment variable that causes DBIx::Class to
-dump the SQL statements used to access the database. This is a helpful
-trick when you are trying to debug your database-oriented code. Press
-C<Ctrl-C> to break out of the development server and enter:
+First, let's enable an environment variable that causes L<DBIx::Class>
+to dump the SQL statements used to access the database. This is a
+helpful trick when you are trying to debug your database-oriented code.
+Press C<Ctrl-C> to break out of the development server and enter:
$ export DBIC_TRACE=1
- $ script/myapp_server.pl -r
+ $ script/myapp_server.pl -r
This assumes you are using bash as your shell -- adjust accordingly if
you are using a different shell (for example, under tcsh, use
C<setenv DBIC_TRACE 1>).
B<NOTE:> You can also set this in your code using
-C<$class-E<gt>storage-E<gt>debug(1);>. See
+C<< $class->storage->debug(1); >>. See
L<DBIx::Class::Manual::Troubleshooting> for details (including options
to log to a file instead of displaying to the Catalyst development
server log).
[debug] Statistics enabled
[debug] Loaded plugins:
.----------------------------------------------------------------------------.
- | Catalyst::Plugin::ConfigLoader 0.27 |
+ | Catalyst::Plugin::ConfigLoader 0.30 |
| Catalyst::Plugin::StackTrace 0.11 |
'----------------------------------------------------------------------------'
-
+
[debug] Loaded dispatcher "Catalyst::Dispatcher"
- [debug] Loaded engine "Catalyst::Engine::HTTP"
- [debug] Found home "/home/me/MyApp"
- [debug] Loaded Config "/home/me/MyApp/myapp.conf"
+ [debug] Loaded engine "Catalyst::Engine"
+ [debug] Found home "/home/catalyst/MyApp"
+ [debug] Loaded Config "/home/catalyst/MyApp/myapp.conf"
[debug] Loaded components:
.-----------------------------------------------------------------+----------.
| Class | Type |
| MyApp::Model::DB::BookAuthor | class |
| MyApp::View::HTML | instance |
'-----------------------------------------------------------------+----------'
-
+
[debug] Loaded Private actions:
.----------------------+--------------------------------------+--------------.
| Private | Class | Method |
| /books/index | MyApp::Controller::Books | index |
| /books/list | MyApp::Controller::Books | list |
'----------------------+--------------------------------------+--------------'
-
+
[debug] Loaded Path actions:
.-------------------------------------+--------------------------------------.
| Path | Private |
| /books | /books/index |
| /books/list | /books/list |
'-------------------------------------+--------------------------------------'
-
+
[info] MyApp powered by Catalyst 5.80020
- You can connect to your server at http://debian:3000
+ HTTP::Server::PSGI: Accepting connections at http://0:3000
-B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from the
-'base' directory of your application, not inside the C<script> directory
-itself or it will not be able to locate the C<myapp.db> database file.
+B<NOTE:> Be sure you run the F<script/myapp_server.pl> command from the
+'base' directory of your application, not inside the F<script> directory
+itself or it will not be able to locate the F<myapp.db> database file.
You can use a fully qualified or a relative path to locate the database
file, but we did not specify that when we ran the model helper earlier.
=item *
-Catalyst::Model::DBIC::Schema dynamically created three model classes,
-one to represent each of the three tables in our database
+L<Catalyst::Model::DBIC::Schema> dynamically created three model
+classes, one to represent each of the three tables in our database
(C<MyApp::Model::DB::Author>, C<MyApp::Model::DB::BookAuthor>, and
C<MyApp::Model::DB::Book>).
Next, to view the book list, change the URL in your browser to
L<http://localhost:3000/books/list>. You should get a list of the five
-books loaded by the C<myapp01.sql> script above without any formatting.
+books loaded by the F<myapp01.sql> script above without any formatting.
The rating for each book should appear on each row, but the "Author(s)"
column will still be blank (we will fill that in later).
-Also notice in the output of the C<script/myapp_server.pl> that
-DBIx::Class used the following SQL to retrieve the data:
+Also notice in the output of the F<script/myapp_server.pl> that
+L<DBIx::Class> used the following SQL to retrieve the data:
SELECT me.id, me.title, me.rating FROM book me
In order to create a wrapper, you must first edit your TT view and tell
it where to find your wrapper file.
-Edit your TT view in C<lib/MyApp/View/HTML.pm> and change it to match
+Edit your TT view in F<lib/MyApp/View/HTML.pm> and change it to match
the following:
__PACKAGE__->config(
Next you need to set up your wrapper template. Basically, you'll want
to take the overall layout of your site and put it into this file. For
-the tutorial, open C<root/src/wrapper.tt2> and input the following:
+the tutorial, open F<root/src/wrapper.tt2> and input the following:
<?xml version="1.0" encoding="UTF-8"?>
- <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+ <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" [%#
+ %]"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>[% template.title or "My Catalyst App!" %]</title>
<link rel="stylesheet" href="[% c.uri_for('/static/css/main.css') %]" />
</head>
-
+
<body>
<div id="outer">
<div id="header">
[%# Insert the page title -%]
<h1>[% template.title or site.title %]</h1>
</div>
-
+
<div id="bodyblock">
<div id="menu">
Navigation:
<ul>
<li><a href="[% c.uri_for('/books/list') %]">Home</a></li>
- <li><a href="[% c.uri_for('/') %]" title="Catalyst Welcome Page">Welcome</a></li>
+ <li><a href="[% c.uri_for('/')
+ %]" title="Catalyst Welcome Page">Welcome</a></li>
</ul>
</div><!-- end menu -->
-
+
<div id="content">
[%# Status and error messages %]
<span class="message">[% status_msg %]</span>
[% content %]
</div><!-- end content -->
</div><!-- end bodyblock -->
-
+
<div id="footer">Copyright (c) your name goes here</div>
</div><!-- end outer -->
-
+
</body>
</html>
<span class="error">[% error_msg %]</span>
If we set either message in the Catalyst stash (e.g.,
-C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it will
+C<< $c->stash->{status_msg} = 'Request was successful!' >>) it will
be displayed whenever any view used by that request is rendered. The
C<message> and C<error> CSS styles can be customized to suit your needs
-in the C<root/static/css/main.css> file we create below.
+in the F<root/static/css/main.css> file we create below.
B<Notes:>
The Catalyst stash only lasts for a single HTTP request. If you need to
retain information across requests you can use
-L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use
-Catalyst sessions in the Authentication chapter of the tutorial).
+L<Catalyst::Plugin::Session> (we will use Catalyst sessions in the
+Authentication chapter of the tutorial).
=item *
$ mkdir root/static/css
-Then open the file C<root/static/css/main.css> (the file referenced in
+Then open the file F<root/static/css/main.css> (the file referenced in
the stylesheet href link of our wrapper above) and add the following
content:
Hit "Reload" in your web browser and you should now see a formatted
version of our basic book list. (Again, the development server should
have automatically restarted when you made changes to
-C<lib/MyApp/View/HTML.pm>. If you are not using the "-r" option, you
+F<lib/MyApp/View/HTML.pm>. If you are not using the "-r" option, you
will need to hit C<Ctrl-C> and manually restart it. Also note that the
development server does I<NOT> need to restart for changes to the TT and
static files we created and edited in the C<root> directory -- those
If you take a look at the Schema files automatically generated by
L<DBIx::Class::Schema::Loader>, you will see that it has already defined
C<has_many> and C<belongs_to> relationships on each side of our foreign
-keys. For example, take a look at C<lib/MyApp/Schema/Result/Book.pm> and
+keys. For example, take a look at F<lib/MyApp/Schema/Result/Book.pm> and
notice the following code:
=head1 RELATIONS
"book_authors",
"MyApp::Schema::Result::BookAuthor",
{ "foreign.book_id" => "self.id" },
+ { cascade_copy => 0, cascade_delete => 0 },
);
Each C<Book> "has_many" C<book_authors>, where C<BookAuthor> is the
many-to-many table that allows each Book to have multiple Authors, and
-each Author to have mulitple books. The arguments to C<has_many> are:
+each Author to have multiple books. The arguments to C<has_many> are:
=over 4
Where the third argument is simply the name of the column in the foreign
table. However, the hashref syntax used by
L<DBIx::Class::Schema::Loader> is more flexible (for example, it can
-handle "multi-column" foreign keys).
+handle "multi-column foreign keys").
B<Note:> If you are using older versions of SQLite and related DBIC
tools, you will need to manually define your C<has_many> and
C<belongs_to> relationships. We recommend upgrading to the versions
specified above. :-)
-Have a look at C<lib/MyApp/Schema/Result/BookAuthor.pm> and notice that
+Have a look at F<lib/MyApp/Schema/Result/BookAuthor.pm> and notice that
there is a C<belongs_to> relationship defined that acts as the "mirror
image" to the C<has_many> relationship we just looked at above:
"book",
"MyApp::Schema::Result::Book",
{ id => "book_id" },
- { join_type => "LEFT" },
+ { join_type => "LEFT", on_delete => "CASCADE", on_update => "CASCADE" },
);
The arguments are similar, but see
automatically handle the C<has_many> and C<belongs_to> relationships,
C<many_to_many> relationship bridges (not technically a relationship)
currently need to be manually inserted. To add a C<many_to_many>
-relationship bridge, first edit C<lib/MyApp/Schema/Result/Book.pm> and
+relationship bridge, first edit F<lib/MyApp/Schema/Result/Book.pm> and
add the following text below the C<# You can replace this text...>
comment:
The C<many_to_many> relationship bridge is optional, but it makes it
easier to map a book to its collection of authors. Without it, we would
have to "walk" through the C<book_author> table as in
-C<$book-E<gt>book_author-E<gt>first-E<gt>author-E<gt>last_name> (we will
+C<< $book->book_author->first->author->last_name >> (we will
see examples on how to use DBIx::Class objects in your code soon, but
-note that because C<$book-E<gt>book_author> can return multiple authors,
+note that because C<< $book->book_author >> can return multiple authors,
we have to use C<first> to display a single author). C<many_to_many>
allows us to use the shorter
-C<$book-E<gt>author-E<gt>first-E<gt>last_name>. Note that you cannot
+C<< $book->author->first->last_name >>. Note that you cannot
define a C<many_to_many> relationship bridge without also having the
C<has_many> relationship in place.
-Then edit C<lib/MyApp/Schema/Result/Author.pm> and add the reverse
+Then edit F<lib/MyApp/Schema/Result/Author.pm> and add the reverse
C<many_to_many> relationship bridge for C<Author> as follows (again, be
careful to put in above the C<1;> but below the C<# DO NOT MODIFY THIS
OR ANYTHING ABOVE!> comment):
$ DBIC_TRACE=1 script/myapp_server.pl -r
Make sure that the application loads correctly and that you see the
-three dynamically created model class (one for each of the Result
+three dynamically created model classes (one for each of the Result
Classes we created).
Then hit the URL L<http://localhost:3000/books/list> with your browser
and be sure that the book list still displays correctly.
-B<Note:> You will not see the authors yet because the view does not yet
-use the new relations. Read on to the next section where we update the
-template to do that.
+B<Note:> You will not see the authors yet because the view isn't taking
+advantage of these relationships. Read on to the next section where we
+update the template to do that.
=head1 UPDATING THE VIEW
Let's add a new column to our book list page that takes advantage of the
relationship information we manually added to our schema files in the
-previous section. Edit C<root/src/books/list.tt2> and replace the
+previous section. Edit F<root/src/books/list.tt2> and replace the
"empty" table cell "<td></td>" with the following:
...
DBIx::Class):
SELECT me.id, me.title, me.rating FROM book me:
- SELECT author.id, author.first_name, author.last_name FROM book_author me
+ SELECT author.id, author.first_name, author.last_name FROM book_author me
JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '1'
- SELECT author.id, author.first_name, author.last_name FROM book_author me
+ SELECT author.id, author.first_name, author.last_name FROM book_author me
JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '2'
- SELECT author.id, author.first_name, author.last_name FROM book_author me
+ SELECT author.id, author.first_name, author.last_name FROM book_author me
JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '3'
- SELECT author.id, author.first_name, author.last_name FROM book_author me
+ SELECT author.id, author.first_name, author.last_name FROM book_author me
JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '4'
- SELECT author.id, author.first_name, author.last_name FROM book_author me
+ SELECT author.id, author.first_name, author.last_name FROM book_author me
JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '5'
-Also note in C<root/src/books/list.tt2> that we are using "| html", a
-type of TT filter, to escape characters such as E<lt> and E<gt> to <
+Also note in F<root/src/books/list.tt2> that we are using "| html", a
+type of TT filter, to escape characters such as < and > to <
and > and avoid various types of dangerous hacks against your
application. In a real application, you would probably want to put "|
html" at the end of every field where a user has control over the
information that can appear in that field (and can therefore inject
markup or code if you don't "neutralize" those fields). In addition to
"| html", Template Toolkit has a variety of other useful filters that
-can found in the documentation for
-L<Template::Filters|Template::Filters>.
+can be found in the documentation for L<Template::Filters>. (While we
+are on the topic of security and escaping of dangerous values, one of
+the advantages of using tools like DBIC for database access or
+L<HTML::FormFu> for form management [see
+L<Chapter 9|Catalyst::Manual::Tutorial::09_AdvancedCRUD::09_FormFu>]
+is that they automatically handle most escaping for you and therefore
+dramatically increase the security of your app.)
=head1 RUNNING THE APPLICATION FROM THE COMMAND LINE
In some situations, it can be useful to run your application and display
a page without using a browser. Catalyst lets you do this using the
-C<scripts/myapp_test.pl> script. Just supply the URL you wish to
+F<script/myapp_test.pl> script. Just supply the URL you wish to
display and it will run that request through the normal controller
dispatch logic and use the appropriate view to render the output
(obviously, complex pages may dump a lot of text to your terminal
-window). For example, if you type:
+window). For example, if C<Ctrl+C> out of the development server
+and then type:
$ script/myapp_test.pl "/books/list"
You should get the same text as if you visited
L<http://localhost:3000/books/list> with the normal development server
-and asked your browser to view the page source.
+and asked your browser to view the page source. You can even pipe this
+HTML text output to a text-based browser using a command like:
+
+ $ script/myapp_test.pl "/books/list" | lynx -stdin
+
+And you should see a fully rendered text-based view of your page. (If
+you are following along in Debian 6, type
+C<sudo aptitude -y install lynx> to install lynx.) If you do start
+lynx, you can use the "Q" key to quit.
=head1 OPTIONAL INFORMATION
Once your controller logic has processed the request from a user, it
forwards processing to your view in order to generate the appropriate
response output. Catalyst uses
-L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by default
+L<Catalyst::Action::RenderView> by default
to automatically perform this operation. If you look in
-C<lib/MyApp/Controller/Root.pm>, you should see the empty definition for
+F<lib/MyApp/Controller/Root.pm>, you should see the empty definition for
the C<sub end> method:
sub end : ActionClass('RenderView') {}
=item *
-C<Root.pm> is designed to hold application-wide logic.
+F<Root.pm> is designed to hold application-wide logic.
=item *
C<end> method that's appropriate. For example, if the controller for a
request has an C<end> method defined, it will be called. However, if
the controller does not define a controller-specific C<end> method, the
-"global" C<end> method in C<Root.pm> will be called.
+"global" C<end> method in F<Root.pm> will be called.
=item *
Because the definition includes an C<ActionClass> attribute, the
-L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic will
-be executed B<after> any code inside the definition of C<sub end> is
-run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions> for
-more information on C<ActionClass>.
+L<Catalyst::Action::RenderView> logic will be executed B<after> any code
+inside the definition of C<sub end> is run. See
+L<Catalyst::Manual::Actions> for more information on C<ActionClass>.
=item *
logic in C<RenderView>. However, you can easily extend the
C<RenderView> logic by adding your own code inside the empty method body
(C<{}>) created by the Catalyst Helpers when we first ran the
-C<catalyst.pl> to initialize our application. See
-L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more
+F<catalyst.pl> to initialize our application. See
+L<Catalyst::Action::RenderView> for more
detailed information on how to extend C<RenderView> in C<sub end>.
=back
You should get a page with the following message at the top:
- Caught exception in MyApp::Controller::Root->end "Forced debug -
+ Caught exception in MyApp::Controller::Root->end "Forced debug -
Scrubbed output at /usr/share/perl5/Catalyst/Action/RenderView.pm line 46."
Along with a summary of your application's state at the end of the
processing for that request. The "Stash" section should show a
summarized version of the DBIC book model objects. If desired, you can
adjust the summarization logic (called "scrubbing" logic) -- see
-L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for
+L<Catalyst::Action::RenderView> for
details.
Note that you shouldn't need to worry about "normal clients" using this
By default, C<Catalyst::View::TT> will look for a template that uses the
same name as your controller action, allowing you to save the step of
manually specifying the template name in each action. For example, this
-would allow us to remove the C<$c-E<gt>stash-E<gt>{template} =
-'books/list.tt2';> line of our C<list> action in the Books controller.
+would allow us to remove the
+C<< $c->stash->{template} = 'books/list.tt2'; >>
+line of our C<list> action in the Books controller.
Open C<lib/MyApp/Controller/Books.pm> in your editor and comment out
this line to match the following (only the
-C<$c-E<gt>stash-E<gt>{template}> line has changed):
+C<< $c->stash->{template} >> line has changed):
=head2 list
-
+
Fetch all book objects and pass to books/list.tt2 in stash to be displayed
-
+
=cut
-
+
sub list :Local {
# Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
# 'Context' that's used to 'glue together' the various components
# that make up the application
my ($self, $c) = @_;
-
+
# Retrieve all of the book records as book model objects and store in the
# stash where they can be accessed by the TT template
$c->stash(books => [$c->model('DB::Book')->all]);
-
+
# Set the TT template to use. You will almost always want to do this
# in your action methods (actions methods respond to user input in
# your controllers).
You should now be able to access the L<http://localhost:3000/books/list>
URL as before.
-B<NOTE:> Please note that if you use the default template technique, you
-will B<not> be able to use either the C<$c-E<gt>forward> or the
-C<$c-E<gt>detach> mechanisms (these are discussed in Chapter 2 and
+B<NOTE:> If you use the default template technique, you
+will B<not> be able to use either the C<< $c->forward >> or the
+C<< $c->detach >> mechanisms (these are discussed in Chapter 2 and
Chapter 9 of the Tutorial).
-B<IMPORTANT:> Make sure that you do NOT skip the following section
+B<IMPORTANT:> Make sure that you do B<not> skip the following section
before continuing to the next chapter 4 Basic CRUD.
=head2 Return To A Manually Specified Template
-In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach>
+In order to be able to use C<< $c->forward >> and C<< $c->detach >>
later in the tutorial, you should remove the comment from the statement
-in C<sub list> in C<lib/MyApp/Controller/Books.pm>:
+in C<sub list> in F<lib/MyApp/Controller/Books.pm>:
$c->stash(template => 'books/list.tt2');
-Then delete the C<TEMPLATE_EXTENSION> line in C<lib/MyApp/View/HTML.pm>.
+Then delete the C<TEMPLATE_EXTENSION> line in F<lib/MyApp/View/HTML.pm>.
Check the L<http://localhost:3000/books/list> URL in your browser. It
should look the same manner as with earlier sections.
+You can jump to the next chapter of the tutorial here:
+L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD>
+
+
=head1 AUTHOR
Kennedy Clark, C<hkclark@gmail.com>
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
-<https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
-
-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/>.
+L<https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
-Copyright 2006-2010, Kennedy Clark, under the
+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/>).
projects / catagits/Catalyst-Manual.git / blobdiff