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|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:
93 Session::Store::FastMmap
94 Session::State::Cookie
97 Once again (remain sharp, by now you should be getting the hang of things)
98 include this additional plugin as a new dependency in the Makefile.PL file
103 'Catalyst::Plugin::Authorization::Roles' => '0',
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 for display in the view
180 $c->stash->{book} = $book;
182 # Set the TT template to use
183 $c->stash->{template} = 'books/create_done.tt2';
185 # Provide very simple feedback to the user.
186 $c->response->body('Unauthorized!');
191 To add authorization, we simply wrap the main code of this method in an
192 C<if> statement that calls C<check_user_roles>. If the user does not
193 have the appropriate permissions, they receive an "Unauthorized!"
194 message. Note that we intentionally chose to display the message this
195 way to demonstrate that TT templates will not be used if the response
196 body has already been set. In reality you would probably want to use a
197 technique that maintains the visual continuity of your template layout
198 (for example, using the "status" or "error" message feature added in
199 Chapter 3 or C<detach> to an action that shows 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 Press C<Ctrl-C> to kill the previous server instance (if it's still
210 running) and restart it:
212 $ script/myapp_server.pl
214 Now trying going to L<http://localhost:3000/books/list> and you should
215 be taken to the login page (you might have to C<Shift+Reload> or
216 C<Ctrl+Reload> your browser and/or click the "User Logout" link on the book
217 list page). Try logging in with both C<test01> and C<test02> (both
218 use a password of C<mypass>) and notice how the roles information
219 updates at the bottom of the "Book List" page. Also try the "User Logout"
220 link on the book list page.
222 Now the "url_create" URL will work if you are already logged in as user
223 C<test01>, but receive an authorization failure if you are logged in as
226 http://localhost:3000/books/url_create/test/1/6
228 while logged in as each user. Use one of the "logout" links (or go to
229 L<http://localhost:3000/logout> in your browser directly) when you are
233 =head1 ENABLE MODEL-BASED AUTHORIZATION
235 Hopefully it's fairly obvious that adding detailed permission checking
236 logic to our controllers and view templates isn't a very clean or
237 scalable way to build role-based permissions into out application. As
238 with many other aspects of MVC web development, the goal is to have
239 your controllers and views be an "thin" as possible, with all of the
240 "fancy business logic" built into your model.
242 For example, let's add a method to our C<Books.pm> Result Class to
243 check if a user is allowed to delete a book. Open
244 C<lib/MyApp/Schema/Result/Book.pm> and add the following method
245 (be sure to add it below the "C<DO NOT MODIFY ...>" line):
247 =head2 delete_allowed_by
249 Can the specified user delete the current book?
253 sub delete_allowed_by {
254 my ($self, $user) = @_;
256 # Only allow delete if user has 'admin' role
257 return $user->has_role('admin');
260 Here we call a C<has_role> method on our user object, so we should add
261 this method to our Result Class. Open
262 C<lib/MyApp/Schema/Result/User.pm> and add the following method below
263 the "C<DO NOT MODIFY ...>" line:
267 Check if a user has the specified role
271 use Perl6::Junction qw/any/;
273 my ($self, $role) = @_;
275 # Does this user posses the required role?
276 return any(map { $_->role } $self->roles) eq $role;
279 Now we need to add some enforcement inside our controller. Open
280 C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to
281 match the following code:
289 sub delete :Chained('object') :PathPart('delete') :Args(0) {
293 $c->detach('/error_noperms')
294 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
296 # Use the book object saved by 'object' and delete it along
297 # with related 'book_authors' entries
298 $c->stash->{object}->delete;
300 # Use 'flash' to save information across requests until it's read
301 $c->flash->{status_msg} = "Book deleted";
303 # Redirect the user back to the list page
304 $c->response->redirect($c->uri_for($self->action_for('list')));
307 Here, we C<detach> to an error page if the user is lacking the
308 appropriate permissions. For this to work, we need to make
309 arrangements for the '/error_noperms' action to work. Open
310 C<lib/MyApp/Controller/Root.pm> and add this method:
314 Permissions error screen
318 sub error_noperms :Chained('/') :PathPart('error_noperms') :Args(0) {
321 $c->stash->{template} = 'error_noperms.tt2';
324 And also add the template file by putting the following text into
325 C<root/src/error_noperms.tt2>:
327 <span class="error">Permission Denied</span>
329 Then run the Catalyst development server script:
331 $ script/myapp_server.pl
333 Log in as C<test01> and create several new books using the C<url_create>
336 http://localhost:3000/books/url_create/Test/1/4
338 Then, while still logged in as C<test01>, click the "Delete" link next
339 to one of these books. The book should be removed and you should see
340 the usual green "Book deleted" message. Next, click the "User Logout"
341 link and log back in as C<test02>. Now try deleting one of the books.
342 You should be taken to the red "Permission Denied" message on our
345 Use one of the 'Logout' links (or go to the
346 L<http://localhost:3000/logout> URL directly) when you are done.
351 Kennedy Clark, C<hkclark@gmail.com>
353 Please report any errors, issues or suggestions to the author. The
354 most recent version of the Catalyst Tutorial can be found at
355 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.
357 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
358 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).