3 Catalyst::Manual::Tutorial::06_Authorization - Catalyst Tutorial - Chapter 6: Authorization
8 This is B<Chapter 6 of 10> for the Catalyst tutorial.
10 L<Tutorial Overview|Catalyst::Manual::Tutorial>
16 L<Introduction|Catalyst::Manual::Tutorial::01_Intro>
20 L<Catalyst Basics|Catalyst::Manual::Tutorial::02_CatalystBasics>
24 L<More Catalyst Basics|Catalyst::Manual::Tutorial::03_MoreCatalystBasics>
28 L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD>
32 L<Authentication|Catalyst::Manual::Tutorial::05_Authentication>
40 L<Debugging|Catalyst::Manual::Tutorial::07_Debugging>
44 L<Testing|Catalyst::Manual::Tutorial::08_Testing>
48 L<Advanced CRUD|Catalyst::Manual::Tutorial::09_AdvancedCRUD>
52 L<Appendices|Catalyst::Manual::Tutorial::10_Appendices>
59 This chapter of the tutorial adds role-based authorization to the
60 existing authentication implemented in
61 L<Chapter 5|Catalyst::Manual::Tutorial::05_Authentication>. It provides
62 simple examples of how to use roles in both TT templates and controller
63 actions. The first half looks at basic authorization concepts. The
64 second half looks at how moving your authorization code to your model
65 can simplify your code and make things easier to maintain.
67 Source code for the tutorial in included in the F</root/Final> directory
68 of the Tutorial Virtual machine (one subdirectory per chapter). There
69 are also instructions for downloading the code in
70 L<Catalyst::Manual::Tutorial::01_Intro>.
73 =head1 BASIC AUTHORIZATION
75 In this section you learn the basics of how authorization works under
79 =head2 Update Plugins to Include Support for Authorization
81 Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list:
82 ***TODO: remove stacktrace?
97 Session::State::Cookie
102 Once again, include this additional plugin as a new dependency in the
103 Makefile.PL file like this:
105 requires 'Catalyst::Plugin::Authorization::Roles';
108 =head2 Add Role-Specific Logic to the "Book List" Template
110 Open C<root/src/books/list.tt2> in your editor and add the following
111 lines to the bottom of the file:
114 <p>Hello [% c.user.username %], you have the following roles:</p>
117 [% # Dump list of roles -%]
118 [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %]
122 [% # Add some simple role-specific logic to template %]
123 [% # Use $c->check_user_roles() to check authz -%]
124 [% IF c.check_user_roles('user') %]
125 [% # Give normal users a link for 'logout' %]
126 <a href="[% c.uri_for('/logout') %]">User Logout</a>
129 [% # Can also use $c->user->check_roles() to check authz -%]
130 [% IF c.check_user_roles('admin') %]
131 [% # Give admin users a link for 'create' %]
132 <a href="[% c.uri_for(c.controller.action_for('form_create')) %]">Admin Create</a>
136 This code displays a different combination of links depending on the
137 roles assigned to the user.
140 =head2 Limit Books::add to 'admin' Users
142 C<IF> statements in TT templates simply control the output that is sent
143 to the user's browser; it provides no real enforcement (if users know or
144 guess the appropriate URLs, they are still perfectly free to hit any
145 action within your application). We need to enhance the controller
146 logic to wrap restricted actions with role-validation logic.
148 For example, we might want to restrict the "formless create" action to
149 admin-level users by editing C<lib/MyApp/Controller/Books.pm> and
150 updating C<url_create> to match the following code:
154 Create a book with the supplied title and rating,
155 with manual authorization
159 sub url_create :Chained('base') :PathPart('url_create') :Args(3) {
160 # In addition to self & context, get the title, rating & author_id args
161 # from the URL. Note that Catalyst automatically puts extra information
162 # after the "/<controller_name>/<action_name/" into @_
163 my ($self, $c, $title, $rating, $author_id) = @_;
165 # Check the user's roles
166 if ($c->check_user_roles('admin')) {
167 # Call create() on the book model object. Pass the table
168 # columns/field values we want to set as hash values
169 my $book = $c->model('DB::Book')->create({
174 # Add a record to the join table for this book, mapping to
176 $book->add_to_book_authors({author_id => $author_id});
177 # Note: Above is a shortcut for this:
178 # $book->create_related('book_authors', {author_id => $author_id});
180 # Assign the Book object to the stash and set template
181 $c->stash(book => $book,
182 template => 'books/create_done.tt2');
184 # Provide very simple feedback to the user.
185 $c->response->body('Unauthorized!');
190 To add authorization, we simply wrap the main code of this method in an
191 C<if> statement that calls C<check_user_roles>. If the user does not
192 have the appropriate permissions, they receive an "Unauthorized!"
193 message. Note that we intentionally chose to display the message this
194 way to demonstrate that TT templates will not be used if the response
195 body has already been set. In reality you would probably want to use a
196 technique that maintains the visual continuity of your template layout
197 (for example, using L<Catalyst::Plugin::StateMessage> as shown in the
198 L<last chapter|Catalyst::Manual::Tutorial::05_Authentication> to
199 redirect to an "unauthorized" page).
201 B<TIP>: If you want to keep your existing C<url_create> method, you can
202 create a new copy and comment out the original by making it look like a
203 Pod comment. For example, put something like C<=begin> before
204 C<sub add : Local {> and C<=end> after the closing C<}>.
207 =head2 Try Out Authentication And Authorization
209 Make sure the development server is running:
211 $ script/myapp_server.pl -r
213 Now trying going to L<http://localhost:3000/books/list> and you should
214 be taken to the login page (you might have to C<Shift+Reload> or
215 C<Ctrl+Reload> your browser and/or click the "User Logout" link on the
216 book list page). Try logging in with both C<test01> and C<test02> (both
217 use a password of C<mypass>) and notice how the roles information
218 updates at the bottom of the "Book List" page. Also try the "User
219 Logout" link on the book list page.
221 Now the "url_create" URL will work if you are already logged in as user
222 C<test01>, but receive an authorization failure if you are logged in as
225 http://localhost:3000/books/url_create/test/1/6
227 while logged in as each user. Use one of the "logout" links (or go to
228 L<http://localhost:3000/logout> in your browser directly) when you are
232 =head1 ENABLE MODEL-BASED AUTHORIZATION
234 Hopefully it's fairly obvious that adding detailed permission checking
235 logic to our controllers and view templates isn't a very clean or
236 scalable way to build role-based permissions into out application. As
237 with many other aspects of MVC web development, the goal is to have your
238 controllers and views be an "thin" as possible, with all of the "fancy
239 business logic" built into your model.
241 For example, let's add a method to our C<Books.pm> Result Class to check
242 if a user is allowed to delete a book. Open
243 C<lib/MyApp/Schema/Result/Book.pm> and add the following method (be sure
244 to add it below the "C<DO NOT MODIFY ...>" line):
246 =head2 delete_allowed_by
248 Can the specified user delete the current book?
252 sub delete_allowed_by {
253 my ($self, $user) = @_;
255 # Only allow delete if user has 'admin' role
256 return $user->has_role('admin');
259 Here we call a C<has_role> method on our user object, so we should add
260 this method to our Result Class. Open
261 C<lib/MyApp/Schema/Result/User.pm> and add the following method below
262 the "C<DO NOT MODIFY ...>" line:
266 Check if a user has the specified role
270 use Perl6::Junction qw/any/;
272 my ($self, $role) = @_;
274 # Does this user posses the required role?
275 return any(map { $_->role } $self->roles) eq $role;
278 Let's also add C<Perl6::Junction> to the requirements listed in
281 requires 'Perl6::Junction';
283 B<Note:> Feel free to use C<grep> in lieu of C<Perl6::Junction::any> if
284 you prefer. Also, please don't let the use of the C<Perl6::Junction>
285 module above lead you to believe that Catalyst is somehow dependent on
286 Perl 6... we are simply using that module for its
287 L<easy-to-read|http://blogs.perl.org/users/marc_sebastian_jakobs/2009/11/my-favorite-module-of-the-month-perl6junction.html>
290 Now we need to add some enforcement inside our controller. Open
291 C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to
292 match the following code:
300 sub delete :Chained('object') :PathPart('delete') :Args(0) {
304 $c->detach('/error_noperms')
305 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
307 # Use the book object saved by 'object' and delete it along
308 # with related 'book_authors' entries
309 $c->stash->{object}->delete;
311 # Redirect the user back to the list page
312 $c->response->redirect($c->uri_for($self->action_for('list'),
313 {mid => $c->set_status_msg("Deleted book $id")}));
316 Here, we C<detach> to an error page if the user is lacking the
317 appropriate permissions. For this to work, we need to make arrangements
318 for the '/error_noperms' action to work. Open
319 C<lib/MyApp/Controller/Root.pm> and add this method:
323 Permissions error screen
327 sub error_noperms :Chained('/') :PathPart('error_noperms') :Args(0) {
330 $c->stash(template => 'error_noperms.tt2');
333 And also add the template file by putting the following text into
334 C<root/src/error_noperms.tt2>:
336 <span class="error">Permission Denied</span>
338 Log in as C<test01> and create several new books using the C<url_create>
341 http://localhost:3000/books/url_create/Test/1/4
343 Then, while still logged in as C<test01>, click the "Delete" link next
344 to one of these books. The book should be removed and you should see
345 the usual green "Book deleted" message. Next, click the "User Logout"
346 link and log back in as C<test02>. Now try deleting one of the books.
347 You should be taken to the red "Permission Denied" message on our error
350 Use one of the 'Logout' links (or go to the
351 L<http://localhost:3000/logout> URL directly) when you are done.
356 Kennedy Clark, C<hkclark@gmail.com>
358 Feel free to contact the author for any errors or suggestions, but the
359 best way to report issues is via the CPAN RT Bug system at
360 <https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
362 The most recent version of the Catalyst Tutorial can be found at
363 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.
365 Copyright 2006-2010, Kennedy Clark, under the
366 Creative Commons Attribution Share-Alike License Version 3.0
367 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).