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 Chapter 5. It provides simple
61 examples of how to use roles in both TT templates and controller
62 actions. The first half looks at basic authorization concepts. The
63 second half looks at how moving your authorization code to your model
64 can simplify your code and make things easier to maintain.
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::01_Intro>.
71 =head1 BASIC AUTHORIZATION
73 In this section you learn the basics of how authorization works under
77 =head2 Update Plugins to Include Support for Authorization
79 Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list:
94 Session::State::Cookie
97 Once again, include this additional plugin as a new dependency in
98 the Makefile.PL file like this:
100 requires 'Catalyst::Plugin::Authorization::Roles';
103 =head2 Add Role-Specific Logic to the "Book List" Template
105 Open C<root/src/books/list.tt2> in your editor and add the following
106 lines to the bottom of the file:
109 <p>Hello [% c.user.username %], you have the following roles:</p>
112 [% # Dump list of roles -%]
113 [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %]
117 [% # Add some simple role-specific logic to template %]
118 [% # Use $c->check_user_roles() to check authz -%]
119 [% IF c.check_user_roles('user') %]
120 [% # Give normal users a link for 'logout' %]
121 <a href="[% c.uri_for('/logout') %]">User Logout</a>
124 [% # Can also use $c->user->check_roles() to check authz -%]
125 [% IF c.check_user_roles('admin') %]
126 [% # Give admin users a link for 'create' %]
127 <a href="[% c.uri_for(c.controller.action_for('form_create')) %]">Admin Create</a>
131 This code displays a different combination of links depending on the
132 roles assigned to the user.
135 =head2 Limit Books::add to 'admin' Users
137 C<IF> statements in TT templates simply control the output that is sent
138 to the user's browser; it provides no real enforcement (if users know or
139 guess the appropriate URLs, they are still perfectly free to hit any
140 action within your application). We need to enhance the controller
141 logic to wrap restricted actions with role-validation logic.
143 For example, we might want to restrict the "formless create" action to
144 admin-level users by editing C<lib/MyApp/Controller/Books.pm> and
145 updating C<url_create> to match the following code:
149 Create a book with the supplied title and rating,
150 with manual authorization
154 sub url_create :Chained('base') :PathPart('url_create') :Args(3) {
155 # In addition to self & context, get the title, rating & author_id args
156 # from the URL. Note that Catalyst automatically puts extra information
157 # after the "/<controller_name>/<action_name/" into @_
158 my ($self, $c, $title, $rating, $author_id) = @_;
160 # Check the user's roles
161 if ($c->check_user_roles('admin')) {
162 # Call create() on the book model object. Pass the table
163 # columns/field values we want to set as hash values
164 my $book = $c->model('DB::Book')->create({
169 # Add a record to the join table for this book, mapping to
171 $book->add_to_book_authors({author_id => $author_id});
172 # Note: Above is a shortcut for this:
173 # $book->create_related('book_authors', {author_id => $author_id});
175 # Assign the Book object to the stash and set template
176 $c->stash(book => $book,
177 template => 'books/create_done.tt2');
179 # Provide very simple feedback to the user.
180 $c->response->body('Unauthorized!');
185 To add authorization, we simply wrap the main code of this method in an
186 C<if> statement that calls C<check_user_roles>. If the user does not
187 have the appropriate permissions, they receive an "Unauthorized!"
188 message. Note that we intentionally chose to display the message this
189 way to demonstrate that TT templates will not be used if the response
190 body has already been set. In reality you would probably want to use a
191 technique that maintains the visual continuity of your template layout
192 (for example, using the "status" or "error" message feature added in
193 Chapter 3 or C<detach> to an action that shows an "unauthorized" page).
195 B<TIP>: If you want to keep your existing C<url_create> method, you can
196 create a new copy and comment out the original by making it look like a
197 Pod comment. For example, put something like C<=begin> before
198 C<sub add : Local {> and C<=end> after the closing C<}>.
201 =head2 Try Out Authentication And Authorization
203 Make sure the development server is running:
205 $ script/myapp_server.pl -r
207 Now trying going to L<http://localhost:3000/books/list> and you should
208 be taken to the login page (you might have to C<Shift+Reload> or
209 C<Ctrl+Reload> your browser and/or click the "User Logout" link on the book
210 list page). Try logging in with both C<test01> and C<test02> (both
211 use a password of C<mypass>) and notice how the roles information
212 updates at the bottom of the "Book List" page. Also try the "User Logout"
213 link on the book list page.
215 Now the "url_create" URL will work if you are already logged in as user
216 C<test01>, but receive an authorization failure if you are logged in as
219 http://localhost:3000/books/url_create/test/1/6
221 while logged in as each user. Use one of the "logout" links (or go to
222 L<http://localhost:3000/logout> in your browser directly) when you are
226 =head1 ENABLE MODEL-BASED AUTHORIZATION
228 Hopefully it's fairly obvious that adding detailed permission checking
229 logic to our controllers and view templates isn't a very clean or
230 scalable way to build role-based permissions into out application. As
231 with many other aspects of MVC web development, the goal is to have
232 your controllers and views be an "thin" as possible, with all of the
233 "fancy business logic" built into your model.
235 For example, let's add a method to our C<Books.pm> Result Class to
236 check if a user is allowed to delete a book. Open
237 C<lib/MyApp/Schema/Result/Book.pm> and add the following method
238 (be sure to add it below the "C<DO NOT MODIFY ...>" line):
240 =head2 delete_allowed_by
242 Can the specified user delete the current book?
246 sub delete_allowed_by {
247 my ($self, $user) = @_;
249 # Only allow delete if user has 'admin' role
250 return $user->has_role('admin');
253 Here we call a C<has_role> method on our user object, so we should add
254 this method to our Result Class. Open
255 C<lib/MyApp/Schema/Result/User.pm> and add the following method below
256 the "C<DO NOT MODIFY ...>" line:
260 Check if a user has the specified role
264 use Perl6::Junction qw/any/;
266 my ($self, $role) = @_;
268 # Does this user posses the required role?
269 return any(map { $_->role } $self->roles) eq $role;
272 Let's also add Perl6::Junction to the requirements listed in
275 requires 'Perl6::Junction';
277 Now we need to add some enforcement inside our controller. Open
278 C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to
279 match the following code:
287 sub delete :Chained('object') :PathPart('delete') :Args(0) {
291 $c->detach('/error_noperms')
292 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
294 # Use the book object saved by 'object' and delete it along
295 # with related 'book_authors' entries
296 $c->stash->{object}->delete;
298 # Use 'flash' to save information across requests until it's read
299 $c->flash->{status_msg} = "Book deleted";
301 # Redirect the user back to the list page
302 $c->response->redirect($c->uri_for($self->action_for('list')));
305 Here, we C<detach> to an error page if the user is lacking the
306 appropriate permissions. For this to work, we need to make
307 arrangements for the '/error_noperms' action to work. Open
308 C<lib/MyApp/Controller/Root.pm> and add this method:
312 Permissions error screen
316 sub error_noperms :Chained('/') :PathPart('error_noperms') :Args(0) {
319 $c->stash(template => 'error_noperms.tt2');
322 And also add the template file by putting the following text into
323 C<root/src/error_noperms.tt2>:
325 <span class="error">Permission Denied</span>
327 Log in as C<test01> and create several new books using the C<url_create>
330 http://localhost:3000/books/url_create/Test/1/4
332 Then, while still logged in as C<test01>, click the "Delete" link next
333 to one of these books. The book should be removed and you should see
334 the usual green "Book deleted" message. Next, click the "User Logout"
335 link and log back in as C<test02>. Now try deleting one of the books.
336 You should be taken to the red "Permission Denied" message on our
339 Use one of the 'Logout' links (or go to the
340 L<http://localhost:3000/logout> URL directly) when you are done.
345 Kennedy Clark, C<hkclark@gmail.com>
347 Feel free to contact the author for any errors or suggestions, but the
348 best way to report issues is via the CPAN RT Bug system at
349 <https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
351 The most recent version of the Catalyst Tutorial can be found at
352 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.
354 Copyright 2006-2010, Kennedy Clark, under the
355 Creative Commons Attribution Share-Alike License Version 3.0
356 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).