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, include this additional plugin as a new dependency in
98 the Makefile.PL file like this:
102 'Catalyst::Plugin::Authorization::Roles' => '0',
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 for display in the view
179 $c->stash->{book} = $book;
181 # Set the TT template to use
182 $c->stash->{template} = 'books/create_done.tt2';
184 # Provide very simple feedback to the user.
185 $c->response->body('Unauthorized!');
190 To add authorization, we simply wrap the main code of this method in an
191 C<if> statement that calls C<check_user_roles>. If the user does not
192 have the appropriate permissions, they receive an "Unauthorized!"
193 message. Note that we intentionally chose to display the message this
194 way to demonstrate that TT templates will not be used if the response
195 body has already been set. In reality you would probably want to use a
196 technique that maintains the visual continuity of your template layout
197 (for example, using the "status" or "error" message feature added in
198 Chapter 3 or C<detach> to an action that shows 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 Press C<Ctrl-C> to kill the previous server instance (if it's still
209 running) and restart it:
211 $ script/myapp_server.pl
213 Now trying going to L<http://localhost:3000/books/list> and you should
214 be taken to the login page (you might have to C<Shift+Reload> or
215 C<Ctrl+Reload> your browser and/or click the "User Logout" link on the book
216 list page). Try logging in with both C<test01> and C<test02> (both
217 use a password of C<mypass>) and notice how the roles information
218 updates at the bottom of the "Book List" page. Also try the "User Logout"
219 link on the book list page.
221 Now the "url_create" URL will work if you are already logged in as user
222 C<test01>, but receive an authorization failure if you are logged in as
225 http://localhost:3000/books/url_create/test/1/6
227 while logged in as each user. Use one of the "logout" links (or go to
228 L<http://localhost:3000/logout> in your browser directly) when you are
232 =head1 ENABLE MODEL-BASED AUTHORIZATION
234 Hopefully it's fairly obvious that adding detailed permission checking
235 logic to our controllers and view templates isn't a very clean or
236 scalable way to build role-based permissions into out application. As
237 with many other aspects of MVC web development, the goal is to have
238 your controllers and views be an "thin" as possible, with all of the
239 "fancy business logic" built into your model.
241 For example, let's add a method to our C<Books.pm> Result Class to
242 check if a user is allowed to delete a book. Open
243 C<lib/MyApp/Schema/Result/Book.pm> and add the following method
244 (be sure to add it below the "C<DO NOT MODIFY ...>" line):
246 =head2 delete_allowed_by
248 Can the specified user delete the current book?
252 sub delete_allowed_by {
253 my ($self, $user) = @_;
255 # Only allow delete if user has 'admin' role
256 return $user->has_role('admin');
259 Here we call a C<has_role> method on our user object, so we should add
260 this method to our Result Class. Open
261 C<lib/MyApp/Schema/Result/User.pm> and add the following method below
262 the "C<DO NOT MODIFY ...>" line:
266 Check if a user has the specified role
270 use Perl6::Junction qw/any/;
272 my ($self, $role) = @_;
274 # Does this user posses the required role?
275 return any(map { $_->role } $self->roles) eq $role;
278 Now we need to add some enforcement inside our controller. Open
279 C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to
280 match the following code:
288 sub delete :Chained('object') :PathPart('delete') :Args(0) {
292 $c->detach('/error_noperms')
293 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
295 # Use the book object saved by 'object' and delete it along
296 # with related 'book_authors' entries
297 $c->stash->{object}->delete;
299 # Use 'flash' to save information across requests until it's read
300 $c->flash->{status_msg} = "Book deleted";
302 # Redirect the user back to the list page
303 $c->response->redirect($c->uri_for($self->action_for('list')));
306 Here, we C<detach> to an error page if the user is lacking the
307 appropriate permissions. For this to work, we need to make
308 arrangements for the '/error_noperms' action to work. Open
309 C<lib/MyApp/Controller/Root.pm> and add this method:
313 Permissions error screen
317 sub error_noperms :Chained('/') :PathPart('error_noperms') :Args(0) {
320 $c->stash->{template} = 'error_noperms.tt2';
323 And also add the template file by putting the following text into
324 C<root/src/error_noperms.tt2>:
326 <span class="error">Permission Denied</span>
328 Then run the Catalyst development server script:
330 $ script/myapp_server.pl
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
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 Please report any errors, issues or suggestions to the author. The
353 most recent version of the Catalyst Tutorial can be found at
354 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.
356 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
357 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).