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 Config Information for Authorization
104 Edit C<myapp.conf> and update it to match the following (the
105 C<role_relation> and C<role_field> definitions are new):
107 # rename this file to MyApp.yml and put a : in front of "name" if
108 # you want to use yaml like in old versions of Catalyst
115 # Note this first definition would be the same as setting
116 # __PACKAGE__->config->{authentication}->{realms}->{dbic}
117 # ->{credential} = 'Password' in lib/MyApp.pm
119 # Specify that we are going to do password-based auth
121 # This is the name of the field in the users table with the
122 # password stored in it
123 password_field password
124 # Switch to more secure hashed passwords
126 # Use the SHA-1 hashing algorithm
127 password_hash_type SHA-1
130 # Use DBIC to retrieve username, password & role information
132 # This is the model object created by Catalyst::Model::DBIC
133 # from your schema (you created 'MyApp::Schema::Result::User'
134 # but as the Catalyst startup debug messages show, it was
135 # loaded as 'MyApp::Model::DB::Users').
136 # NOTE: Omit 'MyApp::Model' here just as you would when using
137 # '$c->model("DB::Users)'
139 # This is the name of a many_to_many relation in the users
140 # object that points to the roles for that user
142 # This is the name of field in the roles table that contains
143 # the role information
151 =head2 Add Role-Specific Logic to the "Book List" Template
153 Open C<root/src/books/list.tt2> in your editor and add the following
154 lines to the bottom of the file:
157 <p>Hello [% c.user.username %], you have the following roles:</p>
160 [% # Dump list of roles -%]
161 [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %]
165 [% # Add some simple role-specific logic to template %]
166 [% # Use $c->check_user_roles() to check authz -%]
167 [% IF c.check_user_roles('user') %]
168 [% # Give normal users a link for 'logout' %]
169 <a href="[% c.uri_for('/logout') %]">User Logout</a>
172 [% # Can also use $c->user->check_roles() to check authz -%]
173 [% IF c.check_user_roles('admin') %]
174 [% # Give admin users a link for 'create' %]
175 <a href="[% c.uri_for(c.controller.action_for('form_create')) %]">Admin Create</a>
179 This code displays a different combination of links depending on the
180 roles assigned to the user.
183 =head2 Limit C<Books::add> to C<admin> Users
185 C<IF> statements in TT templates simply control the output that is sent
186 to the user's browser; it provides no real enforcement (if users know or
187 guess the appropriate URLs, they are still perfectly free to hit any
188 action within your application). We need to enhance the controller
189 logic to wrap restricted actions with role-validation logic.
191 For example, we might want to restrict the "formless create" action to
192 admin-level users by editing C<lib/MyApp/Controller/Books.pm> and
193 updating C<url_create> to match the following code:
197 Create a book with the supplied title and rating,
198 with manual authorization
202 sub url_create :Chained('base') :PathPart('url_create') :Args(3) {
203 # In addition to self & context, get the title, rating & author_id args
204 # from the URL. Note that Catalyst automatically puts extra information
205 # after the "/<controller_name>/<action_name/" into @_
206 my ($self, $c, $title, $rating, $author_id) = @_;
208 # Check the user's roles
209 if ($c->check_user_roles('admin')) {
210 # Call create() on the book model object. Pass the table
211 # columns/field values we want to set as hash values
212 my $book = $c->model('DB::Books')->create({
217 # Add a record to the join table for this book, mapping to
219 $book->add_to_book_authors({author_id => $author_id});
220 # Note: Above is a shortcut for this:
221 # $book->create_related('book_authors', {author_id => $author_id});
223 # Assign the Book object to the stash for display in the view
224 $c->stash->{book} = $book;
226 # This is a hack to disable XSUB processing in Data::Dumper
227 # (it's used in the view). This is a work-around for a bug in
228 # the interaction of some versions or Perl, Data::Dumper & DBIC.
229 # You won't need this if you aren't using Data::Dumper (or if
230 # you are running DBIC 0.06001 or greater), but adding it doesn't
231 # hurt anything either.
232 $Data::Dumper::Useperl = 1;
234 # Set the TT template to use
235 $c->stash->{template} = 'books/create_done.tt2';
237 # Provide very simple feedback to the user.
238 $c->response->body('Unauthorized!');
243 To add authorization, we simply wrap the main code of this method in an
244 C<if> statement that calls C<check_user_roles>. If the user does not
245 have the appropriate permissions, they receive an "Unauthorized!"
246 message. Note that we intentionally chose to display the message this
247 way to demonstrate that TT templates will not be used if the response
248 body has already been set. In reality you would probably want to use a
249 technique that maintains the visual continuity of your template layout
250 (for example, using the "status" or "error" message feature added in
251 Chapter 3 or C<detach> to an action that shows an "unauthorized" page).
253 B<TIP>: If you want to keep your existing C<url_create> method, you can
254 create a new copy and comment out the original by making it look like a
255 Pod comment. For example, put something like C<=begin> before
256 C<sub add : Local {> and C<=end> after the closing C<}>.
259 =head2 Try Out Authentication And Authorization
261 Press C<Ctrl-C> to kill the previous server instance (if it's still
262 running) and restart it:
264 $ script/myapp_server.pl
266 Now trying going to L<http://localhost:3000/books/list> and you should
267 be taken to the login page (you might have to C<Shift+Reload> or
268 C<Ctrl+Reload> your browser and/or click the "User Logout" link on the book
269 list page). Try logging in with both C<test01> and C<test02> (both
270 use a password of C<mypass>) and notice how the roles information
271 updates at the bottom of the "Book List" page. Also try the "User Logout"
272 link on the book list page.
274 Now the "url_create" URL will work if you are already logged in as user
275 C<test01>, but receive an authorization failure if you are logged in as
278 http://localhost:3000/books/url_create/test/1/6
280 while logged in as each user. Use one of the "logout" links (or go to
281 L<http://localhost:3000/logout> in your browser directly) when you are
285 =head1 ENABLE MODEL-BASED AUTHORIZATION
287 Hopefully it's fairly obvious that adding detailed permission checking
288 logic to our controllers and view templates isn't a very clean or
289 scalable way to build role-based permissions into out application. As
290 with many other aspects of MVC web development, the goal is to have
291 your controllers and views be an "thin" as possible, with all of the
292 "fancy business logic" built into your model.
294 For example, let's add a method to our C<Books.pm> Result Class to
295 check if a user is allowed to delete a book. Open
296 C<lib/MyApp/Schema/Result/Books.pm> and add the following method
297 (be sure to add it below the "C<DO NOT MODIFY ...>" line):
299 =head2 delete_allowed_by
301 Can the specified user delete the current book?
305 sub delete_allowed_by {
306 my ($self, $user) = @_;
308 # Only allow delete if user has 'admin' role
309 return $user->has_role('admin');
312 Here we call a C<has_role> method on our user object, so we should add
313 this method to our Result Class. Open
314 C<lib/MyApp/Schema/Result/Users.pm> and add this near the top:
316 use Perl6::Junction qw/any/;
318 And then add the following method below the "C<DO NOT MODIFY ...>"
323 Check if a user has the specified role
328 my ($self, $role) = @_;
330 # Does this user posses the required role?
331 return any(map { $_->role } $self->roles) eq $role;
334 Now we need to add some enforcement inside our controller. Open
335 C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to
336 match the following code:
344 sub delete :Chained('object') :PathPart('delete') :Args(0) {
348 $c->detach('/error_noperms')
349 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
351 # Use the book object saved by 'object' and delete it along
352 # with related 'book_authors' entries
353 $c->stash->{object}->delete;
355 # Use 'flash' to save information across requests until it's read
356 $c->flash->{status_msg} = "Book deleted";
358 # Redirect the user back to the list page
359 $c->response->redirect($c->uri_for($self->action_for('list')));
362 Here, we C<detach> to an error page if the user is lacking the
363 appropriate permissions. For this to work, we need to make
364 arrangements for the '/error_noperms' action to work. Open
365 C<lib/MyApp/Controller/Root.pm> and add this method:
369 Permissions error screen
373 sub error_noperms :Chained('/') :PathPath('error_noperms') :Args(0) {
376 $c->stash->{template} = 'error_noperms.tt2';
379 And also add the template file by putting the following text into
380 C<root/src/error_noperms.tt2>:
382 <span class="error">Permission Denied</span>
384 Then run the Catalyst development server script:
386 $ script/myapp_server.pl
388 Log in as C<test01> and create several new books using the C<url_create>
391 http://localhost:3000/books/url_create/Test/1/4
393 Then, while still logged in as C<test01>, click the "Delete" link next
394 to one of these books. The book should be removed and you should see
395 the usual green "Book deleted" message. Next, click the "User Logout"
396 link and log back in as C<test02>. Now try deleting one of the books.
397 You should be taken to the red "Permission Denied" message on our
400 Use one of the 'Logout' links (or go to the
401 L<http://localhost:3000/logout> URL directly) when you are done.
406 Kennedy Clark, C<hkclark@gmail.com>
408 Please report any errors, issues or suggestions to the author. The
409 most recent version of the Catalyst Tutorial can be found at
410 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>.
412 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
413 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).