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 # This is a hack to disable XSUB processing in Data::Dumper
178 # (it's used in the view). This is a work-around for a bug in
179 # the interaction of some versions or Perl, Data::Dumper & DBIC.
180 # You won't need this if you aren't using Data::Dumper (or if
181 # you are running DBIC 0.06001 or greater), but adding it doesn't
182 # hurt anything either.
183 $Data::Dumper::Useperl = 1;
185 # Set the TT template to use
186 $c->stash->{template} = 'books/create_done.tt2';
188 # Provide very simple feedback to the user.
189 $c->response->body('Unauthorized!');
194 To add authorization, we simply wrap the main code of this method in an
195 C<if> statement that calls C<check_user_roles>. If the user does not
196 have the appropriate permissions, they receive an "Unauthorized!"
197 message. Note that we intentionally chose to display the message this
198 way to demonstrate that TT templates will not be used if the response
199 body has already been set. In reality you would probably want to use a
200 technique that maintains the visual continuity of your template layout
201 (for example, using the "status" or "error" message feature added in
202 Chapter 3 or C<detach> to an action that shows an "unauthorized" page).
204 B<TIP>: If you want to keep your existing C<url_create> method, you can
205 create a new copy and comment out the original by making it look like a
206 Pod comment. For example, put something like C<=begin> before
207 C<sub add : Local {> and C<=end> after the closing C<}>.
210 =head2 Try Out Authentication And Authorization
212 Press C<Ctrl-C> to kill the previous server instance (if it's still
213 running) and restart it:
215 $ script/myapp_server.pl
217 Now trying going to L<http://localhost:3000/books/list> and you should
218 be taken to the login page (you might have to C<Shift+Reload> or
219 C<Ctrl+Reload> your browser and/or click the "User Logout" link on the book
220 list page). Try logging in with both C<test01> and C<test02> (both
221 use a password of C<mypass>) and notice how the roles information
222 updates at the bottom of the "Book List" page. Also try the "User Logout"
223 link on the book list page.
225 Now the "url_create" URL will work if you are already logged in as user
226 C<test01>, but receive an authorization failure if you are logged in as
229 http://localhost:3000/books/url_create/test/1/6
231 while logged in as each user. Use one of the "logout" links (or go to
232 L<http://localhost:3000/logout> in your browser directly) when you are
236 =head1 ENABLE MODEL-BASED AUTHORIZATION
238 Hopefully it's fairly obvious that adding detailed permission checking
239 logic to our controllers and view templates isn't a very clean or
240 scalable way to build role-based permissions into out application. As
241 with many other aspects of MVC web development, the goal is to have
242 your controllers and views be an "thin" as possible, with all of the
243 "fancy business logic" built into your model.
245 For example, let's add a method to our C<Books.pm> Result Class to
246 check if a user is allowed to delete a book. Open
247 C<lib/MyApp/Schema/Result/Books.pm> and add the following method
248 (be sure to add it below the "C<DO NOT MODIFY ...>" line):
250 =head2 delete_allowed_by
252 Can the specified user delete the current book?
256 sub delete_allowed_by {
257 my ($self, $user) = @_;
259 # Only allow delete if user has 'admin' role
260 return $user->has_role('admin');
263 Here we call a C<has_role> method on our user object, so we should add
264 this method to our Result Class. Open
265 C<lib/MyApp/Schema/Result/Users.pm> and add the following method below
266 the "C<DO NOT MODIFY ...>" line:
270 Check if a user has the specified role
274 use Perl6::Junction qw/any/;
276 my ($self, $role) = @_;
278 # Does this user posses the required role?
279 return any(map { $_->role } $self->roles) eq $role;
282 Now we need to add some enforcement inside our controller. Open
283 C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to
284 match the following code:
292 sub delete :Chained('object') :PathPart('delete') :Args(0) {
296 $c->detach('/error_noperms')
297 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
299 # Use the book object saved by 'object' and delete it along
300 # with related 'book_authors' entries
301 $c->stash->{object}->delete;
303 # Use 'flash' to save information across requests until it's read
304 $c->flash->{status_msg} = "Book deleted";
306 # Redirect the user back to the list page
307 $c->response->redirect($c->uri_for($self->action_for('list')));
310 Here, we C<detach> to an error page if the user is lacking the
311 appropriate permissions. For this to work, we need to make
312 arrangements for the '/error_noperms' action to work. Open
313 C<lib/MyApp/Controller/Root.pm> and add this method:
317 Permissions error screen
321 sub error_noperms :Chained('/') :PathPath('error_noperms') :Args(0) {
324 $c->stash->{template} = 'error_noperms.tt2';
327 And also add the template file by putting the following text into
328 C<root/src/error_noperms.tt2>:
330 <span class="error">Permission Denied</span>
332 Then run the Catalyst development server script:
334 $ script/myapp_server.pl
336 Log in as C<test01> and create several new books using the C<url_create>
339 http://localhost:3000/books/url_create/Test/1/4
341 Then, while still logged in as C<test01>, click the "Delete" link next
342 to one of these books. The book should be removed and you should see
343 the usual green "Book deleted" message. Next, click the "User Logout"
344 link and log back in as C<test02>. Now try deleting one of the books.
345 You should be taken to the red "Permission Denied" message on our
348 Use one of the 'Logout' links (or go to the
349 L<http://localhost:3000/logout> URL directly) when you are done.
354 Kennedy Clark, C<hkclark@gmail.com>
356 Please report any errors, issues or suggestions to the author. The
357 most recent version of the Catalyst Tutorial can be found at
358 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>.
360 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
361 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).