3 Catalyst::Manual::Tutorial::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::Intro>
20 L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics>
24 L<More Catalyst Basics|Catalyst::Manual::Tutorial::MoreCatalystBasics>
28 L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>
32 L<Authentication|Catalyst::Manual::Tutorial::Authentication>
40 L<Debugging|Catalyst::Manual::Tutorial::Debugging>
44 L<Testing|Catalyst::Manual::Tutorial::Testing>
48 L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD>
52 L<Appendices|Catalyst::Manual::Tutorial::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::Intro|Catalyst::Manual::Tutorial::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:
82 use Catalyst qw/-Debug
92 Session::Store::FastMmap
93 Session::State::Cookie
96 B<Note:> As discussed in MoreCatalystBasics, different versions of
97 C<Catalyst::Devel> have used a variety of methods to load the plugins.
98 You can put the plugins in the C<use Catalyst> statement if you
102 =head2 Add Role-Specific Logic to the "Book List" Template
104 Open C<root/src/books/list.tt2> in your editor and add the following
105 lines to the bottom of the file:
108 <p>Hello [% c.user.username %], you have the following roles:</p>
111 [% # Dump list of roles -%]
112 [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %]
116 [% # Add some simple role-specific logic to template %]
117 [% # Use $c->check_user_roles() to check authz -%]
118 [% IF c.check_user_roles('user') %]
119 [% # Give normal users a link for 'logout' %]
120 <a href="[% c.uri_for('/logout') %]">User Logout</a>
123 [% # Can also use $c->user->check_roles() to check authz -%]
124 [% IF c.check_user_roles('admin') %]
125 [% # Give admin users a link for 'create' %]
126 <a href="[% c.uri_for(c.controller.action_for('form_create')) %]">Admin Create</a>
130 This code displays a different combination of links depending on the
131 roles assigned to the user.
134 =head2 Limit Books::add to 'admin' Users
136 C<IF> statements in TT templates simply control the output that is sent
137 to the user's browser; it provides no real enforcement (if users know or
138 guess the appropriate URLs, they are still perfectly free to hit any
139 action within your application). We need to enhance the controller
140 logic to wrap restricted actions with role-validation logic.
142 For example, we might want to restrict the "formless create" action to
143 admin-level users by editing C<lib/MyApp/Controller/Books.pm> and
144 updating C<url_create> to match the following code:
148 Create a book with the supplied title and rating,
149 with manual authorization
153 sub url_create :Chained('base') :PathPart('url_create') :Args(3) {
154 # In addition to self & context, get the title, rating & author_id args
155 # from the URL. Note that Catalyst automatically puts extra information
156 # after the "/<controller_name>/<action_name/" into @_
157 my ($self, $c, $title, $rating, $author_id) = @_;
159 # Check the user's roles
160 if ($c->check_user_roles('admin')) {
161 # Call create() on the book model object. Pass the table
162 # columns/field values we want to set as hash values
163 my $book = $c->model('DB::Books')->create({
168 # Add a record to the join table for this book, mapping to
170 $book->add_to_book_authors({author_id => $author_id});
171 # Note: Above is a shortcut for this:
172 # $book->create_related('book_authors', {author_id => $author_id});
174 # Assign the Book object to the stash for display in the view
175 $c->stash->{book} = $book;
177 # Set the TT template to use
178 $c->stash->{template} = 'books/create_done.tt2';
180 # Provide very simple feedback to the user.
181 $c->response->body('Unauthorized!');
186 To add authorization, we simply wrap the main code of this method in an
187 C<if> statement that calls C<check_user_roles>. If the user does not
188 have the appropriate permissions, they receive an "Unauthorized!"
189 message. Note that we intentionally chose to display the message this
190 way to demonstrate that TT templates will not be used if the response
191 body has already been set. In reality you would probably want to use a
192 technique that maintains the visual continuity of your template layout
193 (for example, using the "status" or "error" message feature added in
194 Chapter 3 or C<detach> to an action that shows an "unauthorized" page).
196 B<TIP>: If you want to keep your existing C<url_create> method, you can
197 create a new copy and comment out the original by making it look like a
198 Pod comment. For example, put something like C<=begin> before
199 C<sub add : Local {> and C<=end> after the closing C<}>.
202 =head2 Try Out Authentication And Authorization
204 Press C<Ctrl-C> to kill the previous server instance (if it's still
205 running) and restart it:
207 $ script/myapp_server.pl
209 Now trying going to L<http://localhost:3000/books/list> and you should
210 be taken to the login page (you might have to C<Shift+Reload> or
211 C<Ctrl+Reload> your browser and/or click the "User Logout" link on the book
212 list page). Try logging in with both C<test01> and C<test02> (both
213 use a password of C<mypass>) and notice how the roles information
214 updates at the bottom of the "Book List" page. Also try the "User Logout"
215 link on the book list page.
217 Now the "url_create" URL will work if you are already logged in as user
218 C<test01>, but receive an authorization failure if you are logged in as
221 http://localhost:3000/books/url_create/test/1/6
223 while logged in as each user. Use one of the "logout" links (or go to
224 L<http://localhost:3000/logout> in your browser directly) when you are
228 =head1 ENABLE MODEL-BASED AUTHORIZATION
230 Hopefully it's fairly obvious that adding detailed permission checking
231 logic to our controllers and view templates isn't a very clean or
232 scalable way to build role-based permissions into out application. As
233 with many other aspects of MVC web development, the goal is to have
234 your controllers and views be an "thin" as possible, with all of the
235 "fancy business logic" built into your model.
237 For example, let's add a method to our C<Books.pm> Result Class to
238 check if a user is allowed to delete a book. Open
239 C<lib/MyApp/Schema/Result/Books.pm> and add the following method
240 (be sure to add it below the "C<DO NOT MODIFY ...>" line):
242 =head2 delete_allowed_by
244 Can the specified user delete the current book?
248 sub delete_allowed_by {
249 my ($self, $user) = @_;
251 # Only allow delete if user has 'admin' role
252 return $user->has_role('admin');
255 Here we call a C<has_role> method on our user object, so we should add
256 this method to our Result Class. Open
257 C<lib/MyApp/Schema/Result/Users.pm> and add the following method below
258 the "C<DO NOT MODIFY ...>" line:
262 Check if a user has the specified role
266 use Perl6::Junction qw/any/;
268 my ($self, $role) = @_;
270 # Does this user posses the required role?
271 return any(map { $_->role } $self->roles) eq $role;
274 Now we need to add some enforcement inside our controller. Open
275 C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to
276 match the following code:
284 sub delete :Chained('object') :PathPart('delete') :Args(0) {
288 $c->detach('/error_noperms')
289 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
291 # Use the book object saved by 'object' and delete it along
292 # with related 'book_authors' entries
293 $c->stash->{object}->delete;
295 # Use 'flash' to save information across requests until it's read
296 $c->flash->{status_msg} = "Book deleted";
298 # Redirect the user back to the list page
299 $c->response->redirect($c->uri_for($self->action_for('list')));
302 Here, we C<detach> to an error page if the user is lacking the
303 appropriate permissions. For this to work, we need to make
304 arrangements for the '/error_noperms' action to work. Open
305 C<lib/MyApp/Controller/Root.pm> and add this method:
309 Permissions error screen
313 sub error_noperms :Chained('/') :PathPath('error_noperms') :Args(0) {
316 $c->stash->{template} = 'error_noperms.tt2';
319 And also add the template file by putting the following text into
320 C<root/src/error_noperms.tt2>:
322 <span class="error">Permission Denied</span>
324 Then run the Catalyst development server script:
326 $ script/myapp_server.pl
328 Log in as C<test01> and create several new books using the C<url_create>
331 http://localhost:3000/books/url_create/Test/1/4
333 Then, while still logged in as C<test01>, click the "Delete" link next
334 to one of these books. The book should be removed and you should see
335 the usual green "Book deleted" message. Next, click the "User Logout"
336 link and log back in as C<test02>. Now try deleting one of the books.
337 You should be taken to the red "Permission Denied" message on our
340 Use one of the 'Logout' links (or go to the
341 L<http://localhost:3000/logout> URL directly) when you are done.
346 Kennedy Clark, C<hkclark@gmail.com>
348 Please report any errors, issues or suggestions to the author. The
349 most recent version of the Catalyst Tutorial can be found at
350 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>.
352 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
353 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).