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:
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 for display in the view
176 $c->stash->{book} = $book;
178 # Set the TT template to use
179 $c->stash->{template} = 'books/create_done.tt2';
181 # Provide very simple feedback to the user.
182 $c->response->body('Unauthorized!');
187 To add authorization, we simply wrap the main code of this method in an
188 C<if> statement that calls C<check_user_roles>. If the user does not
189 have the appropriate permissions, they receive an "Unauthorized!"
190 message. Note that we intentionally chose to display the message this
191 way to demonstrate that TT templates will not be used if the response
192 body has already been set. In reality you would probably want to use a
193 technique that maintains the visual continuity of your template layout
194 (for example, using the "status" or "error" message feature added in
195 Chapter 3 or C<detach> to an action that shows an "unauthorized" page).
197 B<TIP>: If you want to keep your existing C<url_create> method, you can
198 create a new copy and comment out the original by making it look like a
199 Pod comment. For example, put something like C<=begin> before
200 C<sub add : Local {> and C<=end> after the closing C<}>.
203 =head2 Try Out Authentication And Authorization
205 Press C<Ctrl-C> to kill the previous server instance (if it's still
206 running) and restart it:
208 $ script/myapp_server.pl
210 Now trying going to L<http://localhost:3000/books/list> and you should
211 be taken to the login page (you might have to C<Shift+Reload> or
212 C<Ctrl+Reload> your browser and/or click the "User Logout" link on the book
213 list page). Try logging in with both C<test01> and C<test02> (both
214 use a password of C<mypass>) and notice how the roles information
215 updates at the bottom of the "Book List" page. Also try the "User Logout"
216 link on the book list page.
218 Now the "url_create" URL will work if you are already logged in as user
219 C<test01>, but receive an authorization failure if you are logged in as
222 http://localhost:3000/books/url_create/test/1/6
224 while logged in as each user. Use one of the "logout" links (or go to
225 L<http://localhost:3000/logout> in your browser directly) when you are
229 =head1 ENABLE MODEL-BASED AUTHORIZATION
231 Hopefully it's fairly obvious that adding detailed permission checking
232 logic to our controllers and view templates isn't a very clean or
233 scalable way to build role-based permissions into out application. As
234 with many other aspects of MVC web development, the goal is to have
235 your controllers and views be an "thin" as possible, with all of the
236 "fancy business logic" built into your model.
238 For example, let's add a method to our C<Books.pm> Result Class to
239 check if a user is allowed to delete a book. Open
240 C<lib/MyApp/Schema/Result/Book.pm> and add the following method
241 (be sure to add it below the "C<DO NOT MODIFY ...>" line):
243 =head2 delete_allowed_by
245 Can the specified user delete the current book?
249 sub delete_allowed_by {
250 my ($self, $user) = @_;
252 # Only allow delete if user has 'admin' role
253 return $user->has_role('admin');
256 Here we call a C<has_role> method on our user object, so we should add
257 this method to our Result Class. Open
258 C<lib/MyApp/Schema/Result/User.pm> and add the following method below
259 the "C<DO NOT MODIFY ...>" line:
263 Check if a user has the specified role
267 use Perl6::Junction qw/any/;
269 my ($self, $role) = @_;
271 # Does this user posses the required role?
272 return any(map { $_->role } $self->roles) eq $role;
275 Now we need to add some enforcement inside our controller. Open
276 C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to
277 match the following code:
285 sub delete :Chained('object') :PathPart('delete') :Args(0) {
289 $c->detach('/error_noperms')
290 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
292 # Use the book object saved by 'object' and delete it along
293 # with related 'book_authors' entries
294 $c->stash->{object}->delete;
296 # Use 'flash' to save information across requests until it's read
297 $c->flash->{status_msg} = "Book deleted";
299 # Redirect the user back to the list page
300 $c->response->redirect($c->uri_for($self->action_for('list')));
303 Here, we C<detach> to an error page if the user is lacking the
304 appropriate permissions. For this to work, we need to make
305 arrangements for the '/error_noperms' action to work. Open
306 C<lib/MyApp/Controller/Root.pm> and add this method:
310 Permissions error screen
314 sub error_noperms :Chained('/') :PathPart('error_noperms') :Args(0) {
317 $c->stash->{template} = 'error_noperms.tt2';
320 And also add the template file by putting the following text into
321 C<root/src/error_noperms.tt2>:
323 <span class="error">Permission Denied</span>
325 Then run the Catalyst development server script:
327 $ script/myapp_server.pl
329 Log in as C<test01> and create several new books using the C<url_create>
332 http://localhost:3000/books/url_create/Test/1/4
334 Then, while still logged in as C<test01>, click the "Delete" link next
335 to one of these books. The book should be removed and you should see
336 the usual green "Book deleted" message. Next, click the "User Logout"
337 link and log back in as C<test02>. Now try deleting one of the books.
338 You should be taken to the red "Permission Denied" message on our
341 Use one of the 'Logout' links (or go to the
342 L<http://localhost:3000/logout> URL directly) when you are done.
347 Kennedy Clark, C<hkclark@gmail.com>
349 Please report any errors, issues or suggestions to the author. The
350 most recent version of the Catalyst Tutorial can be found at
351 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.
353 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
354 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).