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:
96 Session::State::Cookie
101 Once again, include this additional plugin as a new dependency in the
102 Makefile.PL file like this:
104 requires 'Catalyst::Plugin::Authorization::Roles';
107 =head2 Add Role-Specific Logic to the "Book List" Template
109 Open C<root/src/books/list.tt2> in your editor and add the following
110 lines to the bottom of the file:
113 <p>Hello [% c.user.username %], you have the following roles:</p>
116 [% # Dump list of roles -%]
117 [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %]
121 [% # Add some simple role-specific logic to template %]
122 [% # Use $c->check_user_roles() to check authz -%]
123 [% IF c.check_user_roles('user') %]
124 [% # Give normal users a link for 'logout' %]
125 <a href="[% c.uri_for('/logout') %]">User Logout</a>
128 [% # Can also use $c->user->check_roles() to check authz -%]
129 [% IF c.check_user_roles('admin') %]
130 [% # Give admin users a link for 'create' %]
131 <a href="[% c.uri_for(c.controller.action_for('form_create')) %]">Admin Create</a>
135 This code displays a different combination of links depending on the
136 roles assigned to the user.
139 =head2 Limit Books::add to 'admin' Users
141 C<IF> statements in TT templates simply control the output that is sent
142 to the user's browser; it provides no real enforcement (if users know or
143 guess the appropriate URLs, they are still perfectly free to hit any
144 action within your application). We need to enhance the controller
145 logic to wrap restricted actions with role-validation logic.
147 For example, we might want to restrict the "formless create" action to
148 admin-level users by editing C<lib/MyApp/Controller/Books.pm> and
149 updating C<url_create> to match the following code:
153 Create a book with the supplied title and rating,
154 with manual authorization
158 sub url_create :Chained('base') :PathPart('url_create') :Args(3) {
159 # In addition to self & context, get the title, rating & author_id args
160 # from the URL. Note that Catalyst automatically puts extra information
161 # after the "/<controller_name>/<action_name/" into @_
162 my ($self, $c, $title, $rating, $author_id) = @_;
164 # Check the user's roles
165 if ($c->check_user_roles('admin')) {
166 # Call create() on the book model object. Pass the table
167 # columns/field values we want to set as hash values
168 my $book = $c->model('DB::Book')->create({
173 # Add a record to the join table for this book, mapping to
175 $book->add_to_book_authors({author_id => $author_id});
176 # Note: Above is a shortcut for this:
177 # $book->create_related('book_authors', {author_id => $author_id});
179 # Assign the Book object to the stash and set template
180 $c->stash(book => $book,
181 template => 'books/create_done.tt2');
183 # Provide very simple feedback to the user.
184 $c->response->body('Unauthorized!');
189 To add authorization, we simply wrap the main code of this method in an
190 C<if> statement that calls C<check_user_roles>. If the user does not
191 have the appropriate permissions, they receive an "Unauthorized!"
192 message. Note that we intentionally chose to display the message this
193 way to demonstrate that TT templates will not be used if the response
194 body has already been set. In reality you would probably want to use a
195 technique that maintains the visual continuity of your template layout
196 (for example, using L<Catalyst::Plugin::StateMessage> as shown in the
197 L<last chapter|Catalyst::Manual::Tutorial::05_Authentication> to
198 redirect to an "unauthorized" page).
200 B<TIP>: If you want to keep your existing C<url_create> method, you can
201 create a new copy and comment out the original by making it look like a
202 Pod comment. For example, put something like C<=begin> before
203 C<sub add : Local {> and C<=end> after the closing C<}>.
206 =head2 Try Out Authentication And Authorization
208 Make sure the development server is running:
210 $ script/myapp_server.pl -r
212 Now trying going to L<http://localhost:3000/books/list> and you should
213 be taken to the login page (you might have to C<Shift+Reload> or
214 C<Ctrl+Reload> your browser and/or click the "User Logout" link on the
215 book list page). Try logging in with both C<test01> and C<test02> (both
216 use a password of C<mypass>) and notice how the roles information
217 updates at the bottom of the "Book List" page. Also try the "User
218 Logout" link on the book list page.
220 Now the "url_create" URL will work if you are already logged in as user
221 C<test01>, but receive an authorization failure if you are logged in as
224 http://localhost:3000/books/url_create/test/1/6
226 while logged in as each user. Use one of the "logout" links (or go to
227 L<http://localhost:3000/logout> in your browser directly) when you are
231 =head1 ENABLE MODEL-BASED AUTHORIZATION
233 Hopefully it's fairly obvious that adding detailed permission checking
234 logic to our controllers and view templates isn't a very clean or
235 scalable way to build role-based permissions into out application. As
236 with many other aspects of MVC web development, the goal is to have your
237 controllers and views be an "thin" as possible, with all of the "fancy
238 business logic" built into your model.
240 For example, let's add a method to our C<Books.pm> Result Class to check
241 if a user is allowed to delete a book. Open
242 C<lib/MyApp/Schema/Result/Book.pm> and add the following method (be sure
243 to add it below the "C<DO NOT MODIFY ...>" line):
245 =head2 delete_allowed_by
247 Can the specified user delete the current book?
251 sub delete_allowed_by {
252 my ($self, $user) = @_;
254 # Only allow delete if user has 'admin' role
255 return $user->has_role('admin');
258 Here we call a C<has_role> method on our user object, so we should add
259 this method to our Result Class. Open
260 C<lib/MyApp/Schema/Result/User.pm> and add the following method below
261 the "C<DO NOT MODIFY ...>" line:
265 Check if a user has the specified role
269 use Perl6::Junction qw/any/;
271 my ($self, $role) = @_;
273 # Does this user posses the required role?
274 return any(map { $_->role } $self->roles) eq $role;
277 Let's also add C<Perl6::Junction> to the requirements listed in
280 requires 'Perl6::Junction';
282 B<Note:> Feel free to use C<grep> in lieu of C<Perl6::Junction::any> if
283 you prefer. Also, please don't let the use of the C<Perl6::Junction>
284 module above lead you to believe that Catalyst is somehow dependent on
285 Perl 6... we are simply using that module for its
286 L<easy-to-read|http://blogs.perl.org/users/marc_sebastian_jakobs/2009/11/my-favorite-module-of-the-month-perl6junction.html>
289 Now we need to add some enforcement inside our controller. Open
290 C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to
291 match the following code:
299 sub delete :Chained('object') :PathPart('delete') :Args(0) {
303 $c->detach('/error_noperms')
304 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
306 # Use the book object saved by 'object' and delete it along
307 # with related 'book_authors' entries
308 $c->stash->{object}->delete;
310 # Redirect the user back to the list page
311 $c->response->redirect($c->uri_for($self->action_for('list'),
312 {mid => $c->set_status_msg("Deleted book $id")}));
315 Here, we C<detach> to an error page if the user is lacking the
316 appropriate permissions. For this to work, we need to make arrangements
317 for the '/error_noperms' action to work. Open
318 C<lib/MyApp/Controller/Root.pm> and add this method:
322 Permissions error screen
326 sub error_noperms :Chained('/') :PathPart('error_noperms') :Args(0) {
329 $c->stash(template => 'error_noperms.tt2');
332 And also add the template file by putting the following text into
333 C<root/src/error_noperms.tt2>:
335 <span class="error">Permission Denied</span>
337 Log in as C<test01> and create several new books using the C<url_create>
340 http://localhost:3000/books/url_create/Test/1/4
342 Then, while still logged in as C<test01>, click the "Delete" link next
343 to one of these books. The book should be removed and you should see
344 the usual green "Book deleted" message. Next, click the "User Logout"
345 link and log back in as C<test02>. Now try deleting one of the books.
346 You should be taken to the red "Permission Denied" message on our error
349 Use one of the 'Logout' links (or go to the
350 L<http://localhost:3000/logout> URL directly) when you are done.
353 You can jump to the next chapter of the tutorial here:
354 L<Debugging|Catalyst::Manual::Tutorial::07_Debugging>
359 Kennedy Clark, C<hkclark@gmail.com>
361 Feel free to contact the author for any errors or suggestions, but the
362 best way to report issues is via the CPAN RT Bug system at
363 <https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
365 The most recent version of the Catalyst Tutorial can be found at
366 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.
368 Copyright 2006-2010, Kennedy Clark, under the
369 Creative Commons Attribution Share-Alike License Version 3.0
370 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).