3 Catalyst::Manual::Tutorial::Authentication - Catalyst Tutorial - Chapter 5: Authentication
8 This is B<Chapter 5 of 10> for the Catalyst tutorial.
10 L<Tutorial Overview|Catalyst::Manual::Tutorial>
16 L<Introduction|Catalyst::Manual::Tutorial::Intro>
20 L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics>
24 L<More Catalyst Basics|Catalyst::Manual::Tutorial::MoreCatalystBasics>
28 L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>
36 L<Authorization|Catalyst::Manual::Tutorial::Authorization>
40 L<Debugging|Catalyst::Manual::Tutorial::Debugging>
44 L<Testing|Catalyst::Manual::Tutorial::Testing>
48 L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD>
52 L<Appendices|Catalyst::Manual::Tutorial::Appendices>
59 Now that we finally have a simple yet functional application, we can
60 focus on providing authentication (with authorization coming next in
63 This chapter of the tutorial is divided into two main sections: 1) basic,
64 cleartext authentication and 2) hash-based authentication.
66 You can checkout the source code for this example from the catalyst
67 subversion repository as per the instructions in
68 L<Catalyst::Manual::Tutorial::Intro|Catalyst::Manual::Tutorial::Intro>.
71 =head1 BASIC AUTHENTICATION
73 This section explores how to add authentication logic to a Catalyst
77 =head2 Add Users and Roles to the Database
79 First, we add both user and role information to the database (we will
80 add the role information here although it will not be used until the
81 authorization section, Chapter 6). Create a new SQL script file by opening
82 C<myapp02.sql> in your editor and insert:
85 -- Add user and role tables, along with a many-to-many join table
88 id INTEGER PRIMARY KEY,
97 id INTEGER PRIMARY KEY,
100 CREATE TABLE user_role (
103 PRIMARY KEY (user_id, role_id)
106 -- Load up some initial test data
108 INSERT INTO user VALUES (1, 'test01', 'mypass', 't01@na.com', 'Joe', 'Blow', 1);
109 INSERT INTO user VALUES (2, 'test02', 'mypass', 't02@na.com', 'Jane', 'Doe', 1);
110 INSERT INTO user VALUES (3, 'test03', 'mypass', 't03@na.com', 'No', 'Go', 0);
111 INSERT INTO role VALUES (1, 'user');
112 INSERT INTO role VALUES (2, 'admin');
113 INSERT INTO user_role VALUES (1, 1);
114 INSERT INTO user_role VALUES (1, 2);
115 INSERT INTO user_role VALUES (2, 1);
116 INSERT INTO user_role VALUES (3, 1);
118 Then load this into the C<myapp.db> database with the following command:
120 $ sqlite3 myapp.db < myapp02.sql
122 =head2 Add User and Role Information to DBIC Schema
124 Although we could manually edit the DBIC schema information to include
125 the new tables added in the previous step, let's use the C<create=static>
126 option on the DBIC model helper to do most of the work for us:
128 $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
129 create=static components=TimeStamp dbi:SQLite:myapp.db
130 exists "/root/dev/MyApp/script/../lib/MyApp/Model"
131 exists "/root/dev/MyApp/script/../t"
132 Dumping manual schema for MyApp::Schema to directory /root/dev/MyApp/script/../lib ...
133 Schema dump completed.
134 exists "/root/dev/MyApp/script/../lib/MyApp/Model/DB.pm"
136 $ ls lib/MyApp/Schema/Result
137 Author.pm BookAuthor.pm Book.pm Role.pm User.pm UserRole.pm
139 Notice how the helper has added three new table-specific result source
140 files to the C<lib/MyApp/Schema/Result> directory. And, more
141 importantly, even if there were changes to the existing result source
142 files, those changes would have only been written above the C<# DO NOT
143 MODIFY THIS OR ANYTHING ABOVE!> comment and your hand-edited
144 enhancements would have been preserved.
146 Speaking of "hand-editted enhancements," we should now add
147 relationship information to the three new result source files. Edit
148 each of these files and add the following information between the C<#
149 DO NOT MODIFY THIS OR ANYTHING ABOVE!> comment and the closing C<1;>:
151 C<lib/MyApp/Schema/Result/User.pm>:
159 # 1) Name of relationship, DBIC will create accessor with this name
160 # 2) Name of the model class referenced by this relationship
161 # 3) Column name in *foreign* table (aka, foreign key in peer table)
162 __PACKAGE__->has_many(map_user_role => 'MyApp::Schema::Result::UserRole', 'user_id');
166 # 1) Name of relationship, DBIC will create accessor with this name
167 # 2) Name of has_many() relationship this many_to_many() is shortcut for
168 # 3) Name of belongs_to() relationship in model class of has_many() above
169 # You must already have the has_many() defined to use a many_to_many().
170 __PACKAGE__->many_to_many(roles => 'map_user_role', 'role');
173 C<lib/MyApp/Schema/Result/Role.pm>:
181 # 1) Name of relationship, DBIC will create accessor with this name
182 # 2) Name of the model class referenced by this relationship
183 # 3) Column name in *foreign* table (aka, foreign key in peer table)
184 __PACKAGE__->has_many(map_user_role => 'MyApp::Schema::Result::UserRole', 'role_id');
187 C<lib/MyApp/Schema/Result/UserRole.pm>:
195 # 1) Name of relationship, DBIC will create accessor with this name
196 # 2) Name of the model class referenced by this relationship
197 # 3) Column name in *this* table
198 __PACKAGE__->belongs_to(user => 'MyApp::Schema::Result::User', 'user_id');
202 # 1) Name of relationship, DBIC will create accessor with this name
203 # 2) Name of the model class referenced by this relationship
204 # 3) Column name in *this* table
205 __PACKAGE__->belongs_to(role => 'MyApp::Schema::Result::Role', 'role_id');
207 The code for these three sets of updates is obviously very similar to
208 the edits we made to the C<Book>, C<Author>, and C<BookAuthor>
209 classes created in Chapter 3.
211 Note that we do not need to make any change to the
212 C<lib/MyApp/Schema.pm> schema file. It simply tells DBIC to load all
213 of the Result Class and ResultSet Class files it finds in below the
214 C<lib/MyApp/Schema> directory, so it will automatically pick up our
215 new table information.
218 =head2 Sanity-Check Reload of Development Server
220 We aren't ready to try out the authentication just yet; we only want
221 to do a quick check to be sure our model loads correctly. Press
222 C<Ctrl-C> to kill the previous server instance (if it's still running)
225 $ script/myapp_server.pl
227 Look for the three new model objects in the startup debug output:
230 .-------------------------------------------------------------------+----------.
232 +-------------------------------------------------------------------+----------+
233 | MyApp::Controller::Books | instance |
234 | MyApp::Controller::Root | instance |
235 | MyApp::Model::DB | instance |
236 | MyApp::Model::DB::Author | class |
237 | MyApp::Model::DB::Book | class |
238 | MyApp::Model::DB::BookAuthor | class |
239 | MyApp::Model::DB::Role | class |
240 | MyApp::Model::DB::User | class |
241 | MyApp::Model::DB::UserRole | class |
242 | MyApp::View::TT | instance |
243 '-------------------------------------------------------------------+----------'
246 Again, notice that your "Result Class" classes have been "re-loaded"
247 by Catalyst under C<MyApp::Model>.
250 =head2 Include Authentication and Session Plugins
252 Edit C<lib/MyApp.pm> and update it as follows (everything below
253 C<StackTrace> is new):
256 use Catalyst qw/-Debug
265 Session::Store::FastMmap
266 Session::State::Cookie
269 B<Note:> As discussed in MoreCatalystBasics, different versions of
270 C<Catalyst::Devel> have used a variety of methods to load the plugins.
271 You can put the plugins in the C<use Catalyst> statement if you prefer.
273 The C<Authentication> plugin supports Authentication while the
274 C<Session> plugins are required to maintain state across multiple HTTP
277 Note that the only required Authentication class is the main one. This
278 is a change that occurred in version 0.09999_01 of the
279 C<Authentication> plugin. You B<do not need> to specify a particular
280 Authentication::Store or Authentication::Credential plugin. Instead,
281 indicate the Store and Credential you want to use in your application
282 configuration (see below).
284 Make sure you include the additional plugins as new dependencies in
285 the Makefile.PL file something like this:
288 'Catalyst::Plugin::Authentication' => '0',
289 'Catalyst::Plugin::Session' => '0',
290 'Catalyst::Plugin::Session::Store::FastMmap' => '0',
291 'Catalyst::Plugin::Session::State::Cookie' => '0',
294 Note that there are several options for
295 L<Session::Store|Catalyst::Plugin::Session::Store>
296 (L<Session::Store::FastMmap|Catalyst::Plugin::Session::Store::FastMmap>
297 is generally a good choice if you are on Unix; try
298 L<Session::Store::File|Catalyst::Plugin::Session::Store::File> if you
299 are on Win32) -- consult
300 L<Session::Store|Catalyst::Plugin::Session::Store> and its subclasses
301 for additional information and options (for example to use a database-
302 backed session store).
305 =head2 Configure Authentication
307 There are a variety of ways to provide configuration information to
308 L<Catalyst::Plugin::Authentication|Catalyst::Plugin::Authentication>.
310 L<Catalyst::Authentication::Realm::SimpleDB|Catalyst::Authentication::Realm::SimpleDB>
311 because it automatically sets a reasonable set of defaults for us. Open
312 C<lib/MyApp.pm> and place the following text above the call to
313 C<__PACKAGE__-E<gt>setup();>:
315 # Configure SimpleDB Authentication
316 __PACKAGE__->config->{'Plugin::Authentication'} = {
319 user_model => 'DB::User',
320 password_type => 'clear',
324 We could have placed this configuration in C<myapp.conf>, but placing
325 it in C<lib/MyApp.pm> is probably a better place since it's not likely
326 something that users of your application will want to change during
327 deployment (or you could use a mixture: leave C<class> and
328 C<user_model> defined in C<lib/MyApp.pm> as we show above, but place
329 C<password_type> in C<myapp.conf> to allow the type of password to be
330 easily modified during deployment). We will stick with putting
331 all of the authentication-related configuration in C<lib/MyApp.pm>
332 for the tutorial, but if you wish to use C<myapp.conf>, just convert
333 to the following code:
335 <Plugin::Authentication>
338 password_type self_check
342 </Plugin::Authentication>
344 B<TIP:> Here is a short script that will dump the contents of
345 C<MyApp->config> to L<Config::General|Config::General> format in
348 $ perl -Ilib -e 'use MyApp; use Config::General;
349 Config::General->new->save_file("myapp.conf", MyApp->config);'
351 B<NOTE:> Because we are using SimpleDB along with a database layout
352 that complies with its default assumptions, we don't need to specify
353 the names of the columns where our username and password information
354 is stored (hence, the "Simple" part of "SimpleDB"). That being said,
355 SimpleDB lets you specify that type of information if you need to.
357 C<Catalyst::Authentication::Realm::SimpleDB|Catalyst::Authentication::Realm::SimpleDB>
361 =head2 Add Login and Logout Controllers
363 Use the Catalyst create script to create two stub controller files:
365 $ script/myapp_create.pl controller Login
366 $ script/myapp_create.pl controller Logout
368 You could easily use a single controller here. For example, you could
369 have a C<User> controller with both C<login> and C<logout> actions.
370 Remember, Catalyst is designed to be very flexible, and leaves such
371 matters up to you, the designer and programmer.
373 Then open C<lib/MyApp/Controller/Login.pm>, locate the
374 C<sub index :Path :Args(0)> method (or C<sub index : Private> if you
375 are using an older version of Catalyst) that was automatically
376 inserted by the helpers when we created the Login controller above,
377 and update the definition of C<sub index> to match:
385 sub index :Path :Args(0) {
388 # Get the username and password from form
389 my $username = $c->request->params->{username} || "";
390 my $password = $c->request->params->{password} || "";
392 # If the username and password values were found in form
393 if ($username && $password) {
394 # Attempt to log the user in
395 if ($c->authenticate({ username => $username,
396 password => $password } )) {
397 # If successful, then let them use the application
398 $c->response->redirect($c->uri_for(
399 $c->controller('Books')->action_for('list')));
402 # Set an error message
403 $c->stash->{error_msg} = "Bad username or password.";
407 # If either of above don't work out, send to the login page
408 $c->stash->{template} = 'login.tt2';
411 Be sure to remove the C<$c-E<gt>response-E<gt>body('Matched MyApp::Controller::Login in Login.');>
412 line of the C<sub index>.
414 This controller fetches the C<username> and C<password> values from the
415 login form and attempts to authenticate the user. If successful, it
416 redirects the user to the book list page. If the login fails, the user
417 will stay at the login page and receive an error message. If the
418 C<username> and C<password> values are not present in the form, the
419 user will be taken to the empty login form.
421 Note that we could have used something like "C<sub default :Path>",
422 however, it is generally recommended (partly for historical reasons,
423 and partly for code clarity) only to use C<default> in
424 C<MyApp::Controller::Root>, and then mainly to generate the 404 not
425 found page for the application.
427 Instead, we are using "C<sub somename :Path :Args(0) {...}>" here to
428 specifically match the URL C</login>. C<Path> actions (aka, "literal
429 actions") create URI matches relative to the namespace of the
430 controller where they are defined. Although C<Path> supports
431 arguments that allow relative and absolute paths to be defined, here
432 we use an empty C<Path> definition to match on just the name of the
433 controller itself. The method name, C<index>, is arbitrary. We make
434 the match even more specific with the C<:Args(0)> action modifier --
435 this forces the match on I<only> C</login>, not
436 C</login/somethingelse>.
438 Next, update the corresponding method in
439 C<lib/MyApp/Controller/Logout.pm> to match:
447 sub index :Path :Args(0) {
450 # Clear the user's state
453 # Send the user to the starting point
454 $c->response->redirect($c->uri_for('/'));
457 As with the login controller, be sure to delete the
458 C<$c-E<gt>response-E<gt>body('Matched MyApp::Controller::Logout in Logout.');>
459 line of the C<sub index>.
462 =head2 Add a Login Form TT Template Page
464 Create a login form by opening C<root/src/login.tt2> and inserting:
466 [% META title = 'Login' %]
469 <form method="post" action="[% c.uri_for('/login') %]">
473 <td><input type="text" name="username" size="40" /></td>
477 <td><input type="password" name="password" size="40" /></td>
480 <td colspan="2"><input type="submit" name="submit" value="Submit" /></td>
486 =head2 Add Valid User Check
488 We need something that provides enforcement for the authentication
489 mechanism -- a I<global> mechanism that prevents users who have not
490 passed authentication from reaching any pages except the login page.
491 This is generally done via an C<auto> action/method (prior to Catalyst
492 v5.66, this sort of thing would go in C<MyApp.pm>, but starting in
493 v5.66, the preferred location is C<lib/MyApp/Controller/Root.pm>).
495 Edit the existing C<lib/MyApp/Controller/Root.pm> class file and insert
496 the following method:
500 Check if there is a user and, if not, forward to login page
504 # Note that 'auto' runs after 'begin' but before your actions and that
505 # 'auto's "chain" (all from application path to most specific class are run)
506 # See the 'Actions' section of 'Catalyst::Manual::Intro' for more info.
510 # Allow unauthenticated users to reach the login page. This
511 # allows unauthenticated users to reach any action in the Login
512 # controller. To lock it down to a single action, we could use:
513 # if ($c->action eq $c->controller('Login')->action_for('index'))
514 # to only allow unauthenticated access to the 'index' action we
516 if ($c->controller eq $c->controller('Login')) {
520 # If a user doesn't exist, force login
521 if (!$c->user_exists) {
522 # Dump a log message to the development server debug output
523 $c->log->debug('***Root::auto User not found, forwarding to /login');
524 # Redirect the user to the login page
525 $c->response->redirect($c->uri_for('/login'));
526 # Return 0 to cancel 'post-auto' processing and prevent use of application
530 # User found, so return 1 to continue with processing after this 'auto'
535 L<Catalyst::Manual::Tutorial::MoreCatalystBasics/CREATE A CATALYST CONTROLLER>,
536 every C<auto> method from the application/root controller down to the
537 most specific controller will be called. By placing the
538 authentication enforcement code inside the C<auto> method of
539 C<lib/MyApp/Controller/Root.pm> (or C<lib/MyApp.pm>), it will be
540 called for I<every> request that is received by the entire
544 =head2 Displaying Content Only to Authenticated Users
546 Let's say you want to provide some information on the login page that
547 changes depending on whether the user has authenticated yet. To do
548 this, open C<root/src/login.tt2> in your editor and add the following
549 lines to the bottom of the file:
554 # This code illustrates how certain parts of the TT
555 # template will only be shown to users who have logged in
557 [% IF c.user_exists %]
558 Please Note: You are already logged in as '[% c.user.username %]'.
559 You can <a href="[% c.uri_for('/logout') %]">logout</a> here.
561 You need to log in to use this application.
564 Note that this whole block is a comment because the "#" appears
565 immediate after the "[%" (with no spaces in between). Although it
566 can be a handy way to temporarily "comment out" a whole block of
567 TT code, it's probably a little too subtle for use in "normal"
572 Although most of the code is comments, the middle few lines provide a
573 "you are already logged in" reminder if the user returns to the login
574 page after they have already authenticated. For users who have not yet
575 authenticated, a "You need to log in..." message is displayed (note the
576 use of an IF-THEN-ELSE construct in TT).
579 =head2 Try Out Authentication
581 Press C<Ctrl-C> to kill the previous server instance (if it's still
582 running) and restart it:
584 $ script/myapp_server.pl
586 B<IMPORTANT NOTE:> If you are having issues with authentication on
587 Internet Explorer, be sure to check the system clocks on both your
588 server and client machines. Internet Explorer is very picky about
589 timestamps for cookies. You can quickly sync a Debian system by
590 installing the "ntpdate" package:
592 sudo aptitude -y install ntpdate
594 And then run the following command:
598 Or, depending on your firewall configuration:
600 sudo ntpdate-debian -u
602 Note: NTP can be a little more finicky about firewalls because it uses
603 UDP vs. the more common TCP that you see with most Internet protocols.
604 Worse case, you might have to manually set the time on your development
605 box instead of using NTP.
607 Now trying going to L<http://localhost:3000/books/list> and you should
608 be redirected to the login page, hitting Shift+Reload or Ctrl+Reload
609 if necessary (the "You are already logged in" message should I<not>
610 appear -- if it does, click the C<logout> button and try again). Note
611 the C<***Root::auto User not found...> debug message in the
612 development server output. Enter username C<test01> and password
613 C<mypass>, and you should be taken to the Book List page.
615 Open C<root/src/books/list.tt2> and add the following lines to the
616 bottom (below the closing </table> tag):
619 <a href="[% c.uri_for('/login') %]">Login</a>
620 <a href="[% c.uri_for(c.controller.action_for('form_create')) %]">Create</a>
623 Reload your browser and you should now see a "Login" and "Create" links
624 at the bottom of the page (as mentioned earlier, you can update template
625 files without reloading the development server). Click the first link
626 to return to the login page. This time you I<should> see the "You are
627 already logged in" message.
629 Finally, click the C<You can logout here> link on the C</login> page.
630 You should stay at the login page, but the message should change to "You
631 need to log in to use this application."
634 =head1 USING PASSWORD HASHES
636 In this section we increase the security of our system by converting
637 from cleartext passwords to SHA-1 password hashes that include a
638 random "salt" value to make them extremely difficult to crack with
639 dictionary and "rainbow table" attacks.
641 B<Note:> This section is optional. You can skip it and the rest of the
642 tutorial will function normally.
644 Be aware that even with the techniques shown in this section, the browser
645 still transmits the passwords in cleartext to your application. We are
646 just avoiding the I<storage> of cleartext passwords in the database by
647 using a salted SHA-1 hash. If you are concerned about cleartext passwords
648 between the browser and your application, consider using SSL/TLS, made
649 easy with the Catalyst plugin Catalyst::Plugin:RequireSSL.
652 =head2 Install DBIx::Class::EncodedColumn
654 L<DBIx::Class::EncodedColumn|DBIx::Class::EncodedColumn> provides features
655 that can greatly simplify the maintenance of passwords. It's currently
656 not available as a .deb package in the normal Debian repositories, so let's
657 install it directly from CPAN:
659 $ sudo cpan DBIx::Class::EncodedColumn
662 =head2 Re-Run the DBIC::Schema Model Helper to Include DBIx::Class::EncodedColumn
664 Next, we can re-run the model helper to have it include
665 L<DBIx::Class::EncodedColumn|DBIx::Class::EncodedColumn> in all of the
666 Result Classes it generates for us. Simply use the same command we
667 saw in Chapters 3 and 4, but add C<,EncodedColumn> to the C<components>
670 $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
671 create=static components=TimeStamp,EncodedColumn dbi:SQLite:myapp.db
673 If you then open one of the Result Classes, you will see that it
674 includes EncodedColumn in the C<load_components> line. Take a look at
675 C<lib/MyApp/Schema/Result/User.pm> since that's the main class where we
676 want to use hashed and salted passwords:
678 __PACKAGE__->load_components("InflateColumn::DateTime", "TimeStamp", "EncodedColumn", "Core");
681 =head2 Modify the "password" Column to Use EncodedColumn
683 Open the file C<lib/MyApp/Schema/Result/User.pm> and enter the following
684 text below the "# DO NOT MODIFY THIS OR ANYTHING ABOVE!" line but above
687 # Have the 'password' column use a SHA-1 hash and 10-character salt
688 # with hex encoding; Generate the 'check_password" method
689 __PACKAGE__->add_columns(
694 encode_class => 'Digest',
695 encode_args => {salt_length => 10},
696 encode_check_method => 'check_password',
700 This redefines the automatically generated definition for the password
701 fields at the top of the Result Class file to now use EncodedColumn
702 logic (C<encoded_column> is set to 1). C<encode_class> can be set to
703 either C<Digest> to use
704 L<DBIx::Class::EncodedColumn::Digest|DBIx::Class::EncodedColumn::Digest>,
705 or C<Crypt::Eksblowfish::Bcrypt> for
706 L<DBIx::Class::EncodedColumn::Crypt::Eksblowfish::Bcrypt|DBIx::Class::EncodedColumn::Crypt::Eksblowfish::Bcrypt>.
707 C<encode_args> is then used to customize the type of Digest you
708 selected. Here we only specified the size of the salt to use, but
709 we could have also modified the hashing algorithm ('SHA-256' is
710 the default) and the format to use ('base64' is the default, but
711 'hex' and 'binary' are other options). To use these, you could
712 change the C<encode_args> to something like:
714 encode_args => {algorithm => 'SHA-1',
719 =head2 Load Hashed Passwords in the Database
721 Next, let's create a quick script to load some hashed and salted passwords
722 into the C<password> column of our C<users> table. Open the file
723 C<set_hashed_passwords.pl> in your editor and enter the following text:
732 my $schema = MyApp::Schema->connect('dbi:SQLite:myapp.db');
734 my @users = $schema->resultset('User')->all;
736 foreach my $user (@users) {
737 $user->password('mypass');
741 EncodedColumn lets us simple call C<$user->check_password($password)>
742 to see if the user has supplied the correct password, or, as we show
743 above, call C<$user->update($new_password)> to update the hashed
744 password stored for this user.
746 Then run the following command:
748 $ perl -Ilib set_hashed_passwords.pl
750 We had to use the C<-Ilib> arguement to tell perl to look under the
751 C<lib> directory for our C<MyApp::Schema> model.
753 Then dump the users table to verify that it worked:
755 $ sqlite3 myapp.db "select * from user"
756 1|test01|38d3974fa9e9263099f7bc2574284b2f55473a9bM=fwpX2NR8|t01@na.com|Joe|Blow|1
757 2|test02|6ed8586587e53e0d7509b1cfed5df08feadc68cbMJlnPyPt0I|t02@na.com|Jane|Doe|1
758 3|test03|af929a151340c6aed4d54d7e2651795d1ad2e2f7UW8dHoGv9z|t03@na.com|No|Go|0
760 As you can see, the passwords are much harder to steal from the
761 database. Also note that this demonstrates how to use a DBIx::Class
762 model outside of your web application -- a very useful feature in many
766 =head2 Enable Hashed and Salted Passwords
768 Edit C<lib/MyApp.pm> and update it to match the following text (the only change
769 is to the C<password_type> field):
771 # Configure SimpleDB Authentication
772 __PACKAGE__->config->{'Plugin::Authentication'} = {
775 user_model => 'DB::User',
776 password_type => 'self_check',
780 The use of C<self_check> will cause
781 Catalyst::Plugin::Authentication::Store::DBIC to call the
782 C<check_password> method we enabled on our C<password> columns.
785 =head2 Try Out the Hashed Passwords
787 Press C<Ctrl-C> to kill the previous server instance (if it's still
788 running) and restart it:
790 $ script/myapp_server.pl
792 You should now be able to go to L<http://localhost:3000/books/list> and
793 login as before. When done, click the "logout" link on the login page
794 (or point your browser at L<http://localhost:3000/logout>).
797 =head1 USING THE SESSION FOR FLASH
799 As discussed in the previous chapter of the tutorial, C<flash> allows
800 you to set variables in a way that is very similar to C<stash>, but it
801 will remain set across multiple requests. Once the value is read, it
802 is cleared (unless reset). Although C<flash> has nothing to do with
803 authentication, it does leverage the same session plugins. Now that
804 those plugins are enabled, let's go back and update the "delete and
805 redirect with query parameters" code seen at the end of the L<Basic
806 CRUD|Catalyst::Manual::Tutorial::BasicCRUD> chapter of the tutorial to
807 take advantage of C<flash>.
809 First, open C<lib/MyApp/Controller/Books.pm> and modify C<sub delete>
810 to match the following (everything after the model search line of code
819 sub delete :Chained('object') :PathPart('delete') :Args(0) {
822 # Use the book object saved by 'object' and delete it along
823 # with related 'book_authors' entries
824 $c->stash->{object}->delete;
826 # Use 'flash' to save information across requests until it's read
827 $c->flash->{status_msg} = "Book deleted";
829 # Redirect the user back to the list page
830 $c->response->redirect($c->uri_for($self->action_for('list')));
833 Next, open C<root/src/wrapper.tt2> and update the TT code to pull from
834 flash vs. the C<status_msg> query parameter:
838 [%# Status and error messages %]
839 <span class="message">[% status_msg || c.flash.status_msg %]</span>
840 <span class="error">[% error_msg %]</span>
841 [%# This is where TT will stick all of your template's contents. -%]
843 </div><!-- end content -->
846 Although the sample above only shows the C<content> div, leave the
847 rest of the file intact -- the only change we made to the C<wrapper.tt2>
848 was to add "C<|| c.request.params.status_msg>" to the
849 C<E<lt>span class="message"E<gt>> line.
854 Restart the development server, log in, and then point your browser to
855 L<http://localhost:3000/books/url_create/Test/1/4> to create an extra
856 several books. Click the "Return to list" link and delete one of the
857 "Test" books you just added. The C<flash> mechanism should retain our
858 "Book deleted" status message across the redirect.
860 B<NOTE:> While C<flash> will save information across multiple requests,
861 I<it does get cleared the first time it is read>. In general, this is
862 exactly what you want -- the C<flash> message will get displayed on
863 the next screen where it's appropriate, but it won't "keep showing up"
864 after that first time (unless you reset it). Please refer to
865 L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> for additional
869 =head2 Switch To Flash-To-Stash
871 Although the a use of flash above works well, the
872 C<status_msg || c.flash.status_msg> statement is a little ugly. A nice
873 alternative is to use the C<flash_to_stash> feature that automatically
874 copies the content of flash to stash. This makes your controller
875 and template code work regardless of where it was directly access, a
876 forward, or a redirect. To enable C<flash_to_stash>, you can either
877 set the value in C<lib/MyApp.pm> by changing the default
878 C<__PACKAGE__-E<gt>config> setting to something like:
882 session => {flash_to_stash => 1}
885 B<or> add the following to C<myapp.conf>:
891 The C<__PACKAGE__-E<gt>config> option is probably preferable here
892 since it's not something you will want to change at runtime without it
893 possibly breaking some of your code.
895 Then edit C<root/src/wrapper.tt2> and change the C<status_msg> line
896 to match the following:
898 <span class="message">[% status_msg %]</span>
900 Restart the development server and go to
901 L<http://localhost:3000/books/list> in your browser. Delete another
902 of the "Test" books you added in the previous step. Flash should still
903 maintain the status message across the redirect even though you are no
904 longer explicitly accessing C<c.flash>.
909 Kennedy Clark, C<hkclark@gmail.com>
911 Please report any errors, issues or suggestions to the author. The
912 most recent version of the Catalyst Tutorial can be found at
913 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>.
915 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
916 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).