=head1 NAME
-Catalyst::Manual::Tutorial::Authentication - Catalyst Tutorial - Part 4: Authentication
+Catalyst::Manual::Tutorial::Authentication - Catalyst Tutorial - Part 5: Authentication
=head1 OVERVIEW
-This is B<Part 4 of 9> for the Catalyst tutorial.
+This is B<Part 5 of 10> for the Catalyst tutorial.
L<Tutorial Overview|Catalyst::Manual::Tutorial>
=item 3
-L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>
+L<More Catalyst Basics|Catalyst::Manual::Tutorial::MoreCatalystBasics>
=item 4
-B<Authentication>
+L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>
=item 5
-L<Authorization|Catalyst::Manual::Tutorial::Authorization>
+B<Authentication>
=item 6
-L<Debugging|Catalyst::Manual::Tutorial::Debugging>
+L<Authorization|Catalyst::Manual::Tutorial::Authorization>
=item 7
-L<Testing|Catalyst::Manual::Tutorial::Testing>
+L<Debugging|Catalyst::Manual::Tutorial::Debugging>
=item 8
-L<AdvancedCRUD|Catalyst::Manual::Tutorial::AdvancedCRUD>
+L<Testing|Catalyst::Manual::Tutorial::Testing>
=item 9
+L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD>
+
+=item 10
+
L<Appendices|Catalyst::Manual::Tutorial::Appendices>
=back
=head1 DESCRIPTION
-Now that we finally have a simple yet functional application, we can
-focus on providing authentication (with authorization coming next in
+Now that we finally have a simple yet functional application, we can
+focus on providing authentication (with authorization coming next in
Part 5).
This part of the tutorial is divided into two main sections: 1) basic,
=head2 Add User and Role Information to DBIC Schema
-This step adds DBIC-based classes for the user-related database tables
-(the role information will not be used until Part 5):
+Although we could manually edit the DBIC schema information to include
+the new tables added in the previous step, let's use the C<create=static>
+option on the DBIC model helper to do most of the work for us:
-Edit C<lib/MyAppDB.pm> and update the contents to match (only the
-C<MyAppDB =E<gt> [qw/Book BookAuthor Author User UserRole Role/]> line
-has changed):
+ $ script/myapp_create.pl model MyAppDB DBIC::Schema MyApp::Schema::MyAppDB create=static dbi:SQLite:myapp.db
+ $ ls lib/MyApp/Schema/MyAppDB
+ Authors.pm BookAuthors.pm Books.pm Roles.pm UserRoles.pm Users.pm
- package MyAppDB;
-
- =head1 NAME
-
- MyAppDB -- DBIC Schema Class
-
- =cut
-
- # Our schema needs to inherit from 'DBIx::Class::Schema'
- use base qw/DBIx::Class::Schema/;
-
- # Need to load the DB Model classes here.
- # You can use this syntax if you want:
- # __PACKAGE__->load_classes(qw/Book BookAuthor Author User UserRole Role/);
- # Also, if you simply want to load all of the classes in a directory
- # of the same name as your schema class (as we do here) you can use:
- # __PACKAGE__->load_classes(qw//);
- # But the variation below is more flexible in that it can be used to
- # load from multiple namespaces.
- __PACKAGE__->load_classes({
- MyAppDB => [qw/Book BookAuthor Author User UserRole Role/]
- });
-
- 1;
+Notice how the helper has added three new table-specific result source
+files to the C<lib/MyApp/Schema/MyApp> directory. And, more
+importantly, even if there were changes to the existing result source
+files, those changes would have only been written above the C<# DO NOT
+MODIFY THIS OR ANYTHING ABOVE!> comment and your hand-editted
+enhancements would have been preserved.
-=head2 Create New "Result Source Objects"
+Speaking of "hand-editted enhancements," we should now add
+relationship information to the three new result source files. Edit
+each of these files and add the following information between the C<#
+DO NOT MODIFY THIS OR ANYTHING ABOVE!> comment and the closing C<1;>:
-Create the following three files with the content shown below.
+C<lib/MyApp/Schema/MyAppDB/Users.pm>:
-C<lib/MyAppDB/User.pm>:
-
- package MyAppDB::User;
-
- use base qw/DBIx::Class/;
-
- # Load required DBIC stuff
- __PACKAGE__->load_components(qw/PK::Auto Core/);
- # Set the table name
- __PACKAGE__->table('users');
- # Set columns in table
- __PACKAGE__->add_columns(qw/id username password email_address first_name last_name/);
- # Set the primary key for the table
- __PACKAGE__->set_primary_key('id');
-
#
# Set relationships:
#
# 1) Name of relationship, DBIC will create accessor with this name
# 2) Name of the model class referenced by this relationship
# 3) Column name in *foreign* table
- __PACKAGE__->has_many(map_user_role => 'MyAppDB::UserRole', 'user_id');
-
-
- =head1 NAME
-
- MyAppDB::User - A model object representing a person with access to the system.
-
- =head1 DESCRIPTION
+ __PACKAGE__->has_many(map_user_role => 'MyApp::Schema::MyAppDB::UserRoles', 'user_id');
- This is an object that represents a row in the 'users' table of your application
- database. It uses DBIx::Class (aka, DBIC) to do ORM.
-
- For Catalyst, this is designed to be used through MyApp::Model::MyAppDB.
- Offline utilities may wish to use this class directly.
-
- =cut
-
- 1;
+ # many_to_many():
+ # args:
+ # 1) Name of relationship, DBIC will create accessor with this name
+ # 2) Name of has_many() relationship this many_to_many() is shortcut for
+ # 3) Name of belongs_to() relationship in model class of has_many() above
+ # You must already have the has_many() defined to use a many_to_many().
+ __PACKAGE__->many_to_many(roles => 'map_user_role', 'role');
-C<lib/MyAppDB/Role.pm>:
+C<lib/MyApp/Schema/MyAppDB/Roles.pm>:
- package MyAppDB::Role;
-
- use base qw/DBIx::Class/;
-
- # Load required DBIC stuff
- __PACKAGE__->load_components(qw/PK::Auto Core/);
- # Set the table name
- __PACKAGE__->table('roles');
- # Set columns in table
- __PACKAGE__->add_columns(qw/id role/);
- # Set the primary key for the table
- __PACKAGE__->set_primary_key('id');
-
#
# Set relationships:
#
# 1) Name of relationship, DBIC will create accessor with this name
# 2) Name of the model class referenced by this relationship
# 3) Column name in *foreign* table
- __PACKAGE__->has_many(map_user_role => 'MyAppDB::UserRole', 'role_id');
-
-
- =head1 NAME
-
- MyAppDB::Role - A model object representing a class of access permissions to
- the system.
-
- =head1 DESCRIPTION
-
- This is an object that represents a row in the 'roles' table of your
- application database. It uses DBIx::Class (aka, DBIC) to do ORM.
-
- For Catalyst, this is designed to be used through MyApp::Model::MyAppDB.
- "Offline" utilities may wish to use this class directly.
-
- =cut
-
- 1;
+ __PACKAGE__->has_many(map_user_role => 'MyApp::Schema::MyAppDB::UserRoles', 'role_id');
-C<lib/MyAppDB/UserRole.pm>:
+C<lib/MyApp/Schema/MyAppDB/UserRoles.pm>:
- package MyAppDB::UserRole;
-
- use base qw/DBIx::Class/;
-
- # Load required DBIC stuff
- __PACKAGE__->load_components(qw/PK::Auto Core/);
- # Set the table name
- __PACKAGE__->table('user_roles');
- # Set columns in table
- __PACKAGE__->add_columns(qw/user_id role_id/);
- # Set the primary key for the table
- __PACKAGE__->set_primary_key(qw/user_id role_id/);
-
#
# Set relationships:
#
# 1) Name of relationship, DBIC will create accessor with this name
# 2) Name of the model class referenced by this relationship
# 3) Column name in *this* table
- __PACKAGE__->belongs_to(user => 'MyAppDB::User', 'user_id');
+ __PACKAGE__->belongs_to(user => 'MyApp::Schema::MyAppDB::Users', 'user_id');
# belongs_to():
# args:
# 1) Name of relationship, DBIC will create accessor with this name
# 2) Name of the model class referenced by this relationship
# 3) Column name in *this* table
- __PACKAGE__->belongs_to(role => 'MyAppDB::Role', 'role_id');
-
-
- =head1 NAME
-
- MyAppDB::UserRole - A model object representing the JOIN between Users and Roles.
-
- =head1 DESCRIPTION
-
- This is an object that represents a row in the 'user_roles' table of your application
- database. It uses DBIx::Class (aka, DBIC) to do ORM.
-
- You probably won't need to use this class directly -- it will be automatically
- used by DBIC where joins are needed.
-
- For Catalyst, this is designed to be used through MyApp::Model::MyAppDB.
- Offline utilities may wish to use this class directly.
-
- =cut
-
- 1;
+ __PACKAGE__->belongs_to(role => 'MyApp::Schema::MyAppDB::Roles', 'role_id');
+
+
+The code for these three sets of updates is obviously very similar to
+the edits we made to the C<Books>, C<Authors>, and C<BookAuthors>
+classes created in Part 3.
-The code for these three result source classes is obviously very familiar to the C<Book>, C<Author>, and C<BookAuthor> classes created in Part 2.
+Note that we do not need to make any change to the
+C<lib/MyApp/Schema/MyAppDB.pm> schema file. It simple tells DBIC to
+load all of the result source files it finds in below the
+C<lib/MyApp/Schema/MyAppDB> directory, so it will automatically pick
+up our new table information.
=head2 Sanity-Check Reload of Development Server
-We aren't ready to try out the authentication just yet; we only want to do a quick check to be sure our model loads correctly. Press C<Ctrl-C> to kill the previous server instance (if it's still running) and restart it:
+We aren't ready to try out the authentication just yet; we only want
+to do a quick check to be sure our model loads correctly. Press
+C<Ctrl-C> to kill the previous server instance (if it's still running)
+and restart it:
$ script/myapp_server.pl
| MyApp::Controller::Root | instance |
| MyApp::Model::MyAppDB | instance |
| MyApp::Model::MyAppDB::Author | class |
- | MyApp::Model::MyAppDB::Book | class |
- | MyApp::Model::MyAppDB::BookAuthor | class |
- | MyApp::Model::MyAppDB::Role | class |
- | MyApp::Model::MyAppDB::User | class |
- | MyApp::Model::MyAppDB::UserRole | class |
+ | MyApp::Model::MyAppDB::Books | class |
+ | MyApp::Model::MyAppDB::BookAuthors | class |
+ | MyApp::Model::MyAppDB::Roles | class |
+ | MyApp::Model::MyAppDB::Users | class |
+ | MyApp::Model::MyAppDB::UserRoles | class |
| MyApp::View::TT | instance |
'-------------------------------------------------------------------+----------'
...
-Again, notice that your "result source" classes have been "re-loaded" by Catalyst under C<MyApp::Model>.
+Again, notice that your "result source" classes have been "re-loaded"
+by Catalyst under C<MyApp::Model>.
=head2 Include Authentication and Session Plugins
-Edit C<lib/MyApp.pm> and update it as follows (everything below C<StackTrace> is new):
+Edit C<lib/MyApp.pm> and update it as follows (everything below
+C<StackTrace> is new):
use Catalyst qw/
-Debug
StackTrace
Authentication
- Authentication::Store::DBIC
- Authentication::Credential::Password
Session
Session::Store::FastMmap
Session::State::Cookie
/;
-The three C<Authentication> plugins work together to support
-Authentication while the C<Session> plugins are required to maintain
-state across multiple HTTP requests. Note that there are several
-options for L<Session::Store|Catalyst::Plugin::Session::Store>
-(L<Session::Store::FastMmap|Catalyst::Plugin::Session::Store::FastMmap>
-is generally a good choice if you are on Unix; try
-L<Session::Store::File|Catalyst::Plugin::Session::Store::File> if you
-are on Win32) -- consult
-L<Session::Store|Catalyst::Plugin::Session::Store> and its subclasses
-for additional information and options (for example to use a
-database-backed session store).
+The C<Authentication> plugin supports Authentication while the
+C<Session> plugins are required to maintain state across multiple HTTP
+requests.
+
+Note that the only required Authentication class is the main one. This
+is a change that occurred in version 0.09999_01 of the
+C<Authentication> plugin. You B<do not need> to specify a particular
+Authentication::Store or Authentication::Credential plugin. Instead,
+indicate the Store and Credential you want to use in your application
+configuration (see below).
+
+Note that there are several options for
+L<Session::Store|Catalyst::Plugin::Session::Store>
+(L<Session::Store::FastMmap|Catalyst::Plugin::Session::Store::FastMmap>
+is generally a good choice if you are on Unix; try
+L<Session::Store::File|Catalyst::Plugin::Session::Store::File> if you
+are on Win32) -- consult
+L<Session::Store|Catalyst::Plugin::Session::Store> and its subclasses
+for additional information and options (for example to use a database-
+backed session store).
=head2 Configure Authentication
-Although C<__PACKAGE__-E<gt>config(name =E<gt> 'value');> is still
-supported, newer Catalyst applications tend to place all configuration
-information in C<myapp.yml> and automatically load this information into
-C<MyApp-E<gt>config> using the
-L<ConfigLoader|Catalyst::Plugin::ConfigLoader> plugin. Here, we need
-to load several parameters that tell
-L<Catalyst::Plugin::Authentication|Catalyst::Plugin::Authentication>
+Although C<__PACKAGE__-E<gt>config(name =E<gt> 'value');> is still
+supported, newer Catalyst applications tend to place all configuration
+information in C<myapp.conf> and automatically load this information
+into C<MyApp-E<gt>config> using the
+L<ConfigLoader|Catalyst::Plugin::ConfigLoader> plugin.
+
+First, as noted in Part 3 of the tutorial, Catalyst has recently
+switched from a default config file format of YAML to
+C<Config::General> (an apache-like format). In case you are using
+a version of Catalyst earlier than v5.7014, delete the C<myapp.yml>
+file and simply follow the directions below to create a new
+C<myapp.conf> file.
+
+Here, we need to load several parameters that tell
+L<Catalyst::Plugin::Authentication|Catalyst::Plugin::Authentication>
where to locate information in your database. To do this, edit the
-C<myapp.yml> YAML and update it to match:
-
- ---
- name: MyApp
- authentication:
- dbic:
- # Note this first definition would be the same as setting
- # __PACKAGE__->config->{authentication}->{dbic}->{user_class} = 'MyAppDB::User'
- # in lib/MyApp.pm (IOW, each hash key becomes a "name:" in the YAML file).
- #
- # This is the model object created by Catalyst::Model::DBIC from your
- # schema (you created 'MyAppDB::User' but as the Catalyst startup
- # debug messages show, it was loaded as 'MyApp::Model::MyAppDB::User').
- # NOTE: Omit 'MyApp::Model' to avoid a component lookup issue in Catalyst 5.66
- user_class: MyAppDB::User
- # This is the name of the field in your 'users' table that contains the user's name
- user_field: username
- # This is the name of the field in your 'users' table that contains the password
- password_field: password
- # Other options can go here for hashed passwords
+C<myapp.conf> file and update it to match:
+
+ name MyApp
+ <authentication>
+ default_realm dbic
+ <realms>
+ <dbic>
+ <credential>
+ # Note this first definition would be the same as setting
+ # __PACKAGE__->config->{authentication}->{realms}->{dbic}
+ # ->{credential} = 'Password' in lib/MyApp.pm
+ #
+ # Specify that we are going to do password-based auth
+ class Password
+ # This is the name of the field in the users table with the
+ # password stored in it
+ password_field password
+ # We are using an unencrypted password now
+ password_type clear
+ </credential>
+ <store>
+ # Use DBIC to retrieve username, password & role information
+ class DBIx::Class
+ # This is the model object created by Catalyst::Model::DBIC
+ # from your schema (you created 'MyAppDB::User' but as the
+ # Catalyst startup debug messages show, it was loaded as
+ # 'MyApp::Model::MyAppDB::Users').
+ # NOTE: Omit 'MyApp::Model' here just as you would when using
+ # '$c->model("MyAppDB::Users)'
+ user_class MyAppDB::Users
+ # This is the name of the field in your 'users' table that
+ # contains the user's name
+ id_field username
+ </store>
+ </dbic>
+ </realms>
+ </authentication>
Inline comments in the code above explain how each field is being used.
-B<TIP>: Although YAML uses a very simple and easy-to-ready format, it
-does require the use of a consistent level of indenting. Be sure you
-line up everything on a given 'level' with the same number of indents.
-Also, be sure not to use C<tab> characters (YAML does not support them
-because they are handled inconsistently across editors).
-
+Note that you can use many other config file formats with catalyst.
+See L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader>
+for details.
=head2 Add Login and Logout Controllers
# If the username and password values were found in form
if ($username && $password) {
# Attempt to log the user in
- if ($c->login($username, $password)) {
+ if ($c->authenticate({ username => $username,
+ password => $password} )) {
# If successful, then let them use the application
$c->response->redirect($c->uri_for('/books/list'));
return;
}
This controller fetches the C<username> and C<password> values from the
-login form and attempts to perform a login. If successful, it redirects
-the user to the book list page. If the login fails, the user will stay
-at the login page but receive an error message. If the C<username> and
-C<password> values are not present in the form, the user will be taken
-to the empty login form.
+login form and attempts to authenticate the user. If successful, it
+redirects the user to the book list page. If the login fails, the user
+will stay at the login page but receive an error message. If the
+C<username> and C<password> values are not present in the form, the
+user will be taken to the empty login form.
Note that we could have used something like C<sub default :Private>;
however, the use of C<default> actions is discouraged because it does
modifier -- this forces the match on I<only> C</login>, not
C</login/somethingelse>.
-Next, update the corresponding method in C<lib/MyApp/Controller/Logout.pm>
-to match:
+Next, update the corresponding method in
+C<lib/MyApp/Controller/Logout.pm> to match:
=head2 index
return 1;
}
-B<Note:> Catalyst provides a number of different types of actions, such
-as C<Local>, C<Regex>, and C<Private>. You should refer to
-L<Catalyst::Manual::Intro> for a more detailed explanation, but the
-following bullet points provide a quick introduction:
+
+B<Note:> Catalyst provides a number of different types of actions,
+such as C<Local>, C<Regex>, C<Private> and the new C<Path>. You
+should refer to L<Catalyst::Manual::Intro|Catalyst::Manual::Intro> for
+a more detailed explanation, but the following bullet points provide a
+quick introduction:
=over 4
=item *
-The majority of application use C<Local> actions for items that respond
-to user requests and C<Private> actions for those that do not directly
-respond to user input.
+The majority of application have traditionally use C<Local> actions
+for items that respond to user requests and C<Private> actions for
+those that do not directly respond to user input.
+
+=item *
+
+Newer Catalyst applications tend to use C<Path> actions and the
+C<Args> attribute because of their power and flexibility. You can
+specify the path to match relative to the namespace of the current
+module as an argument to C<Path>. For example C<Path('list')> in
+C<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>.
=item *
-There are five types of C<Private> actions: C<begin>, C<end>,
+Automatic "chaining" of actions by the dispatcher is a powerful
+feature that allows multiple methods to handle a single URL. See
+L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained>
+for more information on chained actions.
+
+=item *
+
+There are five types of build-in C<Private> actions: C<begin>, C<end>,
C<default>, C<index>, and C<auto>.
=item *
TT code, it's probably a little too subtle for use in "normal"
comments.
%]
+ </p>
Although most of the code is comments, the middle few lines provide a
"you are already logged in" reminder if the user returns to the login
the Book List page.
Open C<root/src/books/list.tt2> and add the following lines to the
-bottom:
+bottom (below the closing </table> tag):
<p>
<a href="[% Catalyst.uri_for('/login') %]">Login</a>
C<password_hash_type> are new, everything else is the same):
---
- name: MyApp
- authentication:
- dbic:
- # Note this first definition would be the same as setting
- # __PACKAGE__->config->{authentication}->{dbic}->{user_class} = 'MyAppDB::User'
- # in lib/MyApp.pm (IOW, each hash key becomes a "name:" in the YAML file).
- #
- # This is the model object created by Catalyst::Model::DBIC from your
- # schema (you created 'MyAppDB::User' but as the Catalyst startup
- # debug messages show, it was loaded as 'MyApp::Model::MyAppDB::User').
- # NOTE: Omit 'MyApp::Model' here just as you would when using
- # '$c->model("MyAppDB::User)'
- user_class: MyAppDB::User
- # This is the name of the field in your 'users' table that contains the user's name
- user_field: username
- # This is the name of the field in your 'users' table that contains the password
- password_field: password
- # Other options can go here for hashed passwords
- # Enabled hashed passwords
- password_type: hashed
- # Use the SHA-1 hashing algorithm
- password_hash_type: SHA-1
-
+ name MyApp
+ <authentication>
+ default_realm dbic
+ <realms>
+ <dbic>
+ <credential>
+ # Note this first definition would be the same as setting
+ # __PACKAGE__->config->{authentication}->{realms}->{dbic}
+ # ->{credential} = 'Password' in lib/MyApp.pm
+ #
+ # Specify that we are going to do password-based auth
+ class Password
+ # This is the name of the field in the users table with the
+ # password stored in it
+ password_field password
+ # Switch to more secure hashed passwords
+ password_type hashed
+ # Use the SHA-1 hashing algorithm
+ password_hash_type SHA-1
+ </credential>
+ <store>
+ # Use DBIC to retrieve username, password & role information
+ class DBIx::Class
+ # This is the model object created by Catalyst::Model::DBIC
+ # from your schema (you created 'MyAppDB::User' but as the
+ # Catalyst startup debug messages show, it was loaded as
+ # 'MyApp::Model::MyAppDB::Users').
+ # NOTE: Omit 'MyApp::Model' here just as you would when using
+ # '$c->model("MyAppDB::Users)'
+ user_class MyAppDB::Users
+ # This is the name of the field in your 'users' table that
+ # contains the user's name
+ id_field username
+ </store>
+ </dbic>
+ </realms>
+ </authentication>
=head2 Try Out the Hashed Passwords
login as before. When done, click the "Logout" link on the login page
(or point your browser at L<http://localhost:3000/logout>).
-B<Note:> If you receive the debug screen in your browser with a
-C<Can't call method "stash" on an undefined value...> error message,
-make sure that you are using v0.07 of
-L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL>.
-The following command can be a useful way to quickly dump the version number
-of this module on your system:
-
- perl -MCatalyst::Plugin::Authorization::ACL -e 'print $Catalyst::Plugin::Authorization::ACL::VERSION, "\n";'
-
=head1 USING THE SESSION FOR FLASH
tutorial.
First, open C<lib/MyApp/Controller/Books.pm> and modify C<sub delete>
-to match the following:
+to match the following (everything after the model search line of code
+has changed):
=head2 delete
my ($self, $c, $id) = @_;
# Search for the book and then delete it
- $c->model('MyAppDB::Book')->search({id => $id})->delete_all;
+ $c->model('MyAppDB::Books')->search({id => $id})->delete_all;
# Use 'flash' to save information across requests until it's read
$c->flash->{status_msg} = "Book deleted";
- # Redirect the user back to the list page with status msg as an arg
+ # Redirect the user back to the list page
$c->response->redirect($c->uri_for('/books/list'));
}
=head2 Try Out Flash
Restart the development server and point your browser to
-L<http://localhost:3000/books/url_create/Test/1/4> to create an extra
-book. Click the "Return to list" link and delete the "Test" book you
-just added. The C<flash> mechanism should retain our "Book deleted"
-status message across the redirect.
+L<http://localhost:3000/books/url_create/Test/1/4> to create an extra
+several books. Click the "Return to list" link and delete one of the
+"Test" books you just added. The C<flash> mechanism should retain our
+"Book deleted" status message across the redirect.
B<NOTE:> While C<flash> will save information across multiple requests,
I<it does get cleared the first time it is read>. In general, this is
L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> for additional
information.
+=head2 Switch To Flash-To-Stash
+
+Although the a use of flash above is certainly an improvement over the
+C<status_msg> we employed in Part 4 of the tutorial, the C<status_msg
+|| Catalyst.flash.status_msg> statement is a little ugly. A nice
+alternative is to use the C<flash_to_stash> feature that automatically
+copies the content of flash to stash. This makes your code controller
+and template code work regardless of where it was directly access, a
+forward, or a redirect. To enable C<flash_to_stash>, you can either
+set the value in C<lib/MyApp.pm> by changing the default
+C<__PACKAGE__-E<gt>config> setting to something like:
+
+ __PACKAGE__->config(
+ name => 'MyApp',
+ session => {flash_to_stash => 1}
+ );
+
+B<or> add the following to C<myapp.yml>:
+
+ session:
+ flash_to_stash: 1
+
+The C<__PACKAGE__-E<gt>config> option is probably preferable here
+since it's not something you will want to change at runtime without it
+possibly breaking some of your code.
+
+Then edit C<root/lib/site/layout> and change the C<status_msg> line
+to look like the following:
+
+ <span class="message">[% status_msg %]</span>
+
+Restart the development server and go to
+L<http://localhost:3000/books/list> in your browser. Delete another
+of the "Test" books you added in the previous step. Flash should still
+maintain the status message across the redirect even though you are no
+longer explicitly accessing C<Catalyst.flash>.
+
=head1 AUTHOR