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 You can checkout the source code for this example from the catalyst
68 subversion repository as per the instructions in
69 L<Catalyst::Manual::Tutorial::01_Intro>.
72 =head1 BASIC AUTHORIZATION
74 In this section you learn the basics of how authorization works under
78 =head2 Update Plugins to Include Support for Authorization
80 Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list:
95 Session::State::Cookie
100 Once again, include this additional plugin as a new dependency in the
101 Makefile.PL file like this:
103 requires 'Catalyst::Plugin::Authorization::Roles';
106 =head2 Add Role-Specific Logic to the "Book List" Template
108 Open C<root/src/books/list.tt2> in your editor and add the following
109 lines to the bottom of the file:
112 <p>Hello [% c.user.username %], you have the following roles:</p>
115 [% # Dump list of roles -%]
116 [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %]
120 [% # Add some simple role-specific logic to template %]
121 [% # Use $c->check_user_roles() to check authz -%]
122 [% IF c.check_user_roles('user') %]
123 [% # Give normal users a link for 'logout' %]
124 <a href="[% c.uri_for('/logout') %]">User Logout</a>
127 [% # Can also use $c->user->check_roles() to check authz -%]
128 [% IF c.check_user_roles('admin') %]
129 [% # Give admin users a link for 'create' %]
130 <a href="[% c.uri_for(c.controller.action_for('form_create')) %]">Admin Create</a>
134 This code displays a different combination of links depending on the
135 roles assigned to the user.
138 =head2 Limit Books::add to 'admin' Users
140 C<IF> statements in TT templates simply control the output that is sent
141 to the user's browser; it provides no real enforcement (if users know or
142 guess the appropriate URLs, they are still perfectly free to hit any
143 action within your application). We need to enhance the controller
144 logic to wrap restricted actions with role-validation logic.
146 For example, we might want to restrict the "formless create" action to
147 admin-level users by editing C<lib/MyApp/Controller/Books.pm> and
148 updating C<url_create> to match the following code:
152 Create a book with the supplied title and rating,
153 with manual authorization
157 sub url_create :Chained('base') :PathPart('url_create') :Args(3) {
158 # In addition to self & context, get the title, rating & author_id args
159 # from the URL. Note that Catalyst automatically puts extra information
160 # after the "/<controller_name>/<action_name/" into @_
161 my ($self, $c, $title, $rating, $author_id) = @_;
163 # Check the user's roles
164 if ($c->check_user_roles('admin')) {
165 # Call create() on the book model object. Pass the table
166 # columns/field values we want to set as hash values
167 my $book = $c->model('DB::Book')->create({
172 # Add a record to the join table for this book, mapping to
174 $book->add_to_book_authors({author_id => $author_id});
175 # Note: Above is a shortcut for this:
176 # $book->create_related('book_authors', {author_id => $author_id});
178 # Assign the Book object to the stash and set template
179 $c->stash(book => $book,
180 template => 'books/create_done.tt2');
182 # Provide very simple feedback to the user.
183 $c->response->body('Unauthorized!');
188 To add authorization, we simply wrap the main code of this method in an
189 C<if> statement that calls C<check_user_roles>. If the user does not
190 have the appropriate permissions, they receive an "Unauthorized!"
191 message. Note that we intentionally chose to display the message this
192 way to demonstrate that TT templates will not be used if the response
193 body has already been set. In reality you would probably want to use a
194 technique that maintains the visual continuity of your template layout
195 (for example, using L<Catalyst::Plugin::StateMessage> as shown in the
196 L<last chapter|Catalyst::Manual::Tutorial::05_Authentication> to
197 redirect to an "unauthorized" page).
199 B<TIP>: If you want to keep your existing C<url_create> method, you can
200 create a new copy and comment out the original by making it look like a
201 Pod comment. For example, put something like C<=begin> before
202 C<sub add : Local {> and C<=end> after the closing C<}>.
205 =head2 Try Out Authentication And Authorization
207 Make sure the development server is running:
209 $ script/myapp_server.pl -r
211 Now trying going to L<http://localhost:3000/books/list> and you should
212 be taken to the login page (you might have to C<Shift+Reload> or
213 C<Ctrl+Reload> your browser and/or click the "User Logout" link on the
214 book list page). Try logging in with both C<test01> and C<test02> (both
215 use a password of C<mypass>) and notice how the roles information
216 updates at the bottom of the "Book List" page. Also try the "User
217 Logout" link on the book list page.
219 Now the "url_create" URL will work if you are already logged in as user
220 C<test01>, but receive an authorization failure if you are logged in as
223 http://localhost:3000/books/url_create/test/1/6
225 while logged in as each user. Use one of the "logout" links (or go to
226 L<http://localhost:3000/logout> in your browser directly) when you are
230 =head1 ENABLE MODEL-BASED AUTHORIZATION
232 Hopefully it's fairly obvious that adding detailed permission checking
233 logic to our controllers and view templates isn't a very clean or
234 scalable way to build role-based permissions into out application. As
235 with many other aspects of MVC web development, the goal is to have your
236 controllers and views be an "thin" as possible, with all of the "fancy
237 business logic" built into your model.
239 For example, let's add a method to our C<Books.pm> Result Class to check
240 if a user is allowed to delete a book. Open
241 C<lib/MyApp/Schema/Result/Book.pm> and add the following method (be sure
242 to add it below the "C<DO NOT MODIFY ...>" line):
244 =head2 delete_allowed_by
246 Can the specified user delete the current book?
250 sub delete_allowed_by {
251 my ($self, $user) = @_;
253 # Only allow delete if user has 'admin' role
254 return $user->has_role('admin');
257 Here we call a C<has_role> method on our user object, so we should add
258 this method to our Result Class. Open
259 C<lib/MyApp/Schema/Result/User.pm> and add the following method below
260 the "C<DO NOT MODIFY ...>" line:
264 Check if a user has the specified role
268 use Perl6::Junction qw/any/;
270 my ($self, $role) = @_;
272 # Does this user posses the required role?
273 return any(map { $_->role } $self->roles) eq $role;
276 Let's also add Perl6::Junction to the requirements listed in
279 requires 'Perl6::Junction';
281 Now we need to add some enforcement inside our controller. Open
282 C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to
283 match the following code:
291 sub delete :Chained('object') :PathPart('delete') :Args(0) {
295 $c->detach('/error_noperms')
296 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
298 # Use the book object saved by 'object' and delete it along
299 # with related 'book_authors' entries
300 $c->stash->{object}->delete;
302 # Use 'flash' to save information across requests until it's read
303 $c->flash->{status_msg} = "Book deleted";
305 # Redirect the user back to the list page
306 $c->response->redirect($c->uri_for($self->action_for('list'),
307 {mid => $c->set_status_msg("Deleted book $id")}));
310 Here, we C<detach> to an error page if the user is lacking the
311 appropriate permissions. For this to work, we need to make arrangements
312 for the '/error_noperms' action to work. Open
313 C<lib/MyApp/Controller/Root.pm> and add this method:
317 Permissions error screen
321 sub error_noperms :Chained('/') :PathPart('error_noperms') :Args(0) {
324 $c->stash(template => 'error_noperms.tt2');
327 And also add the template file by putting the following text into
328 C<root/src/error_noperms.tt2>:
330 <span class="error">Permission Denied</span>
332 Log in as C<test01> and create several new books using the C<url_create>
335 http://localhost:3000/books/url_create/Test/1/4
337 Then, while still logged in as C<test01>, click the "Delete" link next
338 to one of these books. The book should be removed and you should see
339 the usual green "Book deleted" message. Next, click the "User Logout"
340 link and log back in as C<test02>. Now try deleting one of the books.
341 You should be taken to the red "Permission Denied" message on our error
344 Use one of the 'Logout' links (or go to the
345 L<http://localhost:3000/logout> URL directly) when you are done.
350 Kennedy Clark, C<hkclark@gmail.com>
352 Feel free to contact the author for any errors or suggestions, but the
353 best way to report issues is via the CPAN RT Bug system at
354 <https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
356 The most recent version of the Catalyst Tutorial can be found at
357 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.
359 Copyright 2006-2010, Kennedy Clark, under the
360 Creative Commons Attribution Share-Alike License Version 3.0
361 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).