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 B<Note:> As discussed in MoreCatalystBasics, different versions of
98 C<Catalyst::Devel> have used a variety of methods to load the plugins.
99 You can put the plugins in the C<use Catalyst> statement if you
102 Once again (remain sharp, by now you should be getting the hang of things)
103 include this additional plugin as a new dependency in the Makefile.PL file
108 'Catalyst::Plugin::Authorization::Roles' => '0',
112 =head2 Add Role-Specific Logic to the "Book List" Template
114 Open C<root/src/books/list.tt2> in your editor and add the following
115 lines to the bottom of the file:
118 <p>Hello [% c.user.username %], you have the following roles:</p>
121 [% # Dump list of roles -%]
122 [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %]
126 [% # Add some simple role-specific logic to template %]
127 [% # Use $c->check_user_roles() to check authz -%]
128 [% IF c.check_user_roles('user') %]
129 [% # Give normal users a link for 'logout' %]
130 <a href="[% c.uri_for('/logout') %]">User Logout</a>
133 [% # Can also use $c->user->check_roles() to check authz -%]
134 [% IF c.check_user_roles('admin') %]
135 [% # Give admin users a link for 'create' %]
136 <a href="[% c.uri_for(c.controller.action_for('form_create')) %]">Admin Create</a>
140 This code displays a different combination of links depending on the
141 roles assigned to the user.
144 =head2 Limit Books::add to 'admin' Users
146 C<IF> statements in TT templates simply control the output that is sent
147 to the user's browser; it provides no real enforcement (if users know or
148 guess the appropriate URLs, they are still perfectly free to hit any
149 action within your application). We need to enhance the controller
150 logic to wrap restricted actions with role-validation logic.
152 For example, we might want to restrict the "formless create" action to
153 admin-level users by editing C<lib/MyApp/Controller/Books.pm> and
154 updating C<url_create> to match the following code:
158 Create a book with the supplied title and rating,
159 with manual authorization
163 sub url_create :Chained('base') :PathPart('url_create') :Args(3) {
164 # In addition to self & context, get the title, rating & author_id args
165 # from the URL. Note that Catalyst automatically puts extra information
166 # after the "/<controller_name>/<action_name/" into @_
167 my ($self, $c, $title, $rating, $author_id) = @_;
169 # Check the user's roles
170 if ($c->check_user_roles('admin')) {
171 # Call create() on the book model object. Pass the table
172 # columns/field values we want to set as hash values
173 my $book = $c->model('DB::Book')->create({
178 # Add a record to the join table for this book, mapping to
180 $book->add_to_book_authors({author_id => $author_id});
181 # Note: Above is a shortcut for this:
182 # $book->create_related('book_authors', {author_id => $author_id});
184 # Assign the Book object to the stash for display in the view
185 $c->stash->{book} = $book;
187 # Set the TT template to use
188 $c->stash->{template} = 'books/create_done.tt2';
190 # Provide very simple feedback to the user.
191 $c->response->body('Unauthorized!');
196 To add authorization, we simply wrap the main code of this method in an
197 C<if> statement that calls C<check_user_roles>. If the user does not
198 have the appropriate permissions, they receive an "Unauthorized!"
199 message. Note that we intentionally chose to display the message this
200 way to demonstrate that TT templates will not be used if the response
201 body has already been set. In reality you would probably want to use a
202 technique that maintains the visual continuity of your template layout
203 (for example, using the "status" or "error" message feature added in
204 Chapter 3 or C<detach> to an action that shows an "unauthorized" page).
206 B<TIP>: If you want to keep your existing C<url_create> method, you can
207 create a new copy and comment out the original by making it look like a
208 Pod comment. For example, put something like C<=begin> before
209 C<sub add : Local {> and C<=end> after the closing C<}>.
212 =head2 Try Out Authentication And Authorization
214 Press C<Ctrl-C> to kill the previous server instance (if it's still
215 running) and restart it:
217 $ script/myapp_server.pl
219 Now trying going to L<http://localhost:3000/books/list> and you should
220 be taken to the login page (you might have to C<Shift+Reload> or
221 C<Ctrl+Reload> your browser and/or click the "User Logout" link on the book
222 list page). Try logging in with both C<test01> and C<test02> (both
223 use a password of C<mypass>) and notice how the roles information
224 updates at the bottom of the "Book List" page. Also try the "User Logout"
225 link on the book list page.
227 Now the "url_create" URL will work if you are already logged in as user
228 C<test01>, but receive an authorization failure if you are logged in as
231 http://localhost:3000/books/url_create/test/1/6
233 while logged in as each user. Use one of the "logout" links (or go to
234 L<http://localhost:3000/logout> in your browser directly) when you are
238 =head1 ENABLE MODEL-BASED AUTHORIZATION
240 Hopefully it's fairly obvious that adding detailed permission checking
241 logic to our controllers and view templates isn't a very clean or
242 scalable way to build role-based permissions into out application. As
243 with many other aspects of MVC web development, the goal is to have
244 your controllers and views be an "thin" as possible, with all of the
245 "fancy business logic" built into your model.
247 For example, let's add a method to our C<Books.pm> Result Class to
248 check if a user is allowed to delete a book. Open
249 C<lib/MyApp/Schema/Result/Book.pm> and add the following method
250 (be sure to add it below the "C<DO NOT MODIFY ...>" line):
252 =head2 delete_allowed_by
254 Can the specified user delete the current book?
258 sub delete_allowed_by {
259 my ($self, $user) = @_;
261 # Only allow delete if user has 'admin' role
262 return $user->has_role('admin');
265 Here we call a C<has_role> method on our user object, so we should add
266 this method to our Result Class. Open
267 C<lib/MyApp/Schema/Result/User.pm> and add the following method below
268 the "C<DO NOT MODIFY ...>" line:
272 Check if a user has the specified role
276 use Perl6::Junction qw/any/;
278 my ($self, $role) = @_;
280 # Does this user posses the required role?
281 return any(map { $_->role } $self->roles) eq $role;
284 Now we need to add some enforcement inside our controller. Open
285 C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to
286 match the following code:
294 sub delete :Chained('object') :PathPart('delete') :Args(0) {
298 $c->detach('/error_noperms')
299 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
301 # Use the book object saved by 'object' and delete it along
302 # with related 'book_authors' entries
303 $c->stash->{object}->delete;
305 # Use 'flash' to save information across requests until it's read
306 $c->flash->{status_msg} = "Book deleted";
308 # Redirect the user back to the list page
309 $c->response->redirect($c->uri_for($self->action_for('list')));
312 Here, we C<detach> to an error page if the user is lacking the
313 appropriate permissions. For this to work, we need to make
314 arrangements for the '/error_noperms' action to work. Open
315 C<lib/MyApp/Controller/Root.pm> and add this method:
319 Permissions error screen
323 sub error_noperms :Chained('/') :PathPart('error_noperms') :Args(0) {
326 $c->stash->{template} = 'error_noperms.tt2';
329 And also add the template file by putting the following text into
330 C<root/src/error_noperms.tt2>:
332 <span class="error">Permission Denied</span>
334 Then run the Catalyst development server script:
336 $ script/myapp_server.pl
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
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 Please report any errors, issues or suggestions to the author. The
359 most recent version of the Catalyst Tutorial can be found at
360 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.
362 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
363 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).