1Catalyst::Manual::TutorUisaelr::C0o6n_tArCuiatbthuaotlreyidsztaP:te:irMolann(Du3oa)clu:m:eTnuttaotriioanl::06_Authorization(3)
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6 Catalyst::Manual::Tutorial::06_Authorization - Catalyst Tutorial -
7 Chapter 6: Authorization
8
10 This is Chapter 6 of 10 for the Catalyst tutorial.
11 Tutorial Overview
13 1. Introduction
15 2. Catalyst Basics
17 3. More Catalyst Basics
19 4. Basic CRUD
21 5. Authentication
23 6. 06_Authorization
25 7. Debugging
27 8. Testing
29 9. Advanced CRUD
31 10. Appendices
33
35 This chapter of the tutorial adds role-based authorization to the
36 existing authentication implemented in Chapter 5. It provides simple
37 examples of how to use roles in both TT templates and controller
38 actions. The first half looks at basic authorization concepts. The
39 second half looks at how moving your authorization code to your model
40 can simplify your code and make things easier to maintain.
41 Source code for the tutorial in included in the /home/catalyst/Final
43 directory of the Tutorial Virtual machine (one subdirectory per
44 chapter). There are also instructions for downloading the code in
45 Catalyst::Manual::Tutorial::01_Intro.
46
48 In this section you learn the basics of how authorization works under
49 Catalyst.
50 Update Plugins to Include Support for Authorization
52 Edit "lib/MyApp.pm" and add "Authorization::Roles" to the list:
53 # Load plugins
55 use Catalyst qw/
56 -Debug
57 ConfigLoader
58 Static::Simple
59 StackTrace
61 Authentication
63 Authorization::Roles
64 Session
66 Session::Store::File
67 Session::State::Cookie
68 StatusMessage
70 /;
71 Once again, include this additional plugin as a new dependency in the
73 Makefile.PL file like this:
74 requires 'Catalyst::Plugin::Authorization::Roles';
76 Add Role-Specific Logic to the "Book List" Template
78 Open "root/src/books/list.tt2" in your editor and add the following
79 lines to the bottom of the file:
80 ...
82 <p>Hello [% c.user.username %], you have the following roles:</p>
83 <ul>
85 [% # Dump list of roles -%]
86 [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %]
87 </ul>
88 <p>
90 [% # Add some simple role-specific logic to template %]
91 [% # Use $c->check_user_roles() to check authz -%]
92 [% IF c.check_user_roles('user') %]
93 [% # Give normal users a link for 'logout' %]
94 <a href="[% c.uri_for('/logout') %]">User Logout</a>
95 [% END %]
96 [% # Can also use $c->user->check_roles() to check authz -%]
98 [% IF c.check_user_roles('admin') %]
99 [% # Give admin users a link for 'create' %]
100 <a href="[% c.uri_for(c.controller.action_for('form_create')) %]">Admin Create</a>
101 [% END %]
102 </p>
103 This code displays a different combination of links depending on the
105 roles assigned to the user.
106 Limit Books::add to 'admin' Users
108 "IF" statements in TT templates simply control the output that is sent
109 to the user's browser; it provides no real enforcement (if users know
110 or guess the appropriate URLs, they are still perfectly free to hit any
111 action within your application). We need to enhance the controller
112 logic to wrap restricted actions with role-validation logic.
113 For example, we might want to restrict the "formless create" action to
115 admin-level users by editing "lib/MyApp/Controller/Books.pm" and
116 updating "url_create" to match the following code:
117 =head2 url_create
119 Create a book with the supplied title and rating,
121 with manual authorization
122 =cut
124 sub url_create :Chained('base') :PathPart('url_create') :Args(3) {
126 # In addition to self & context, get the title, rating & author_id args
127 # from the URL. Note that Catalyst automatically puts extra information
128 # after the "/<controller_name>/<action_name/" into @_
129 my ($self, $c, $title, $rating, $author_id) = @_;
130 # Check the user's roles
132 if ($c->check_user_roles('admin')) {
133 # Call create() on the book model object. Pass the table
134 # columns/field values we want to set as hash values
135 my $book = $c->model('DB::Book')->create({
136 title => $title,
137 rating => $rating
138 });
139 # Add a record to the join table for this book, mapping to
141 # appropriate author
142 $book->add_to_book_authors({author_id => $author_id});
143 # Note: Above is a shortcut for this:
144 # $book->create_related('book_authors', {author_id => $author_id});
145 # Assign the Book object to the stash and set template
147 $c->stash(book => $book,
148 template => 'books/create_done.tt2');
149 } else {
150 # Provide very simple feedback to the user.
151 $c->response->body('Unauthorized!');
152 }
153 }
154 To add authorization, we simply wrap the main code of this method in an
156 "if" statement that calls "check_user_roles". If the user does not
157 have the appropriate permissions, they receive an "Unauthorized!"
158 message. Note that we intentionally chose to display the message this
159 way to demonstrate that TT templates will not be used if the response
160 body has already been set. In reality you would probably want to use a
161 technique that maintains the visual continuity of your template layout
162 (for example, using Catalyst::Plugin::StatusMessage as shown in the
163 last chapter to redirect to an "unauthorized" page).
164 TIP: If you want to keep your existing "url_create" method, you can
166 create a new copy and comment out the original by making it look like a
167 Pod comment. For example, put something like "=begin" before "sub add
168 : Local {" and "=end" after the closing "}".
169 Try Out Authentication And Authorization
171 Make sure the development server is running:
172 $ script/myapp_server.pl -r
174 Now trying going to <http://localhost:3000/books/list> and you should
176 be taken to the login page (you might have to "Shift+Reload" or
177 "Ctrl+Reload" your browser and/or click the "User Logout" link on the
178 book list page). Try logging in with both "test01" and "test02" (both
179 use a password of "mypass") and notice how the roles information
180 updates at the bottom of the "Book List" page. Also try the "User
181 Logout" link on the book list page.
182 Now the "url_create" URL will work if you are already logged in as user
184 "test01", but receive an authorization failure if you are logged in as
185 "test02". Try:
186 http://localhost:3000/books/url_create/test/1/6
188 while logged in as each user. Use one of the "logout" links (or go to
190 <http://localhost:3000/logout> in your browser directly) when you are
191 done.
192
194 Hopefully it's fairly obvious that adding detailed permission checking
195 logic to our controllers and view templates isn't a very clean or
196 scalable way to build role-based permissions into out application. As
197 with many other aspects of MVC web development, the goal is to have
198 your controllers and views be an "thin" as possible, with all of the
199 "fancy business logic" built into your model.
200 For example, let's add a method to our "Books.pm" Result Class to check
202 if a user is allowed to delete a book. Open
203 "lib/MyApp/Schema/Result/Book.pm" and add the following method (be sure
204 to add it below the ""DO NOT MODIFY ..."" line):
205 =head2 delete_allowed_by
207 Can the specified user delete the current book?
209 =cut
211 sub delete_allowed_by {
213 my ($self, $user) = @_;
214 # Only allow delete if user has 'admin' role
216 return $user->has_role('admin');
217 }
218 Here we call a "has_role" method on our user object, so we should add
220 this method to our Result Class. Open
221 "lib/MyApp/Schema/Result/User.pm" and add the following method below
222 the ""DO NOT MODIFY ..."" line:
223 =head2 has_role
225 Check if a user has the specified role
227 =cut
229 use Perl6::Junction qw/any/;
231 sub has_role {
232 my ($self, $role) = @_;
233 # Does this user posses the required role?
235 return any(map { $_->role } $self->roles) eq $role;
236 }
237 Let's also add "Perl6::Junction" to the requirements listed in
239 Makefile.PL:
240 requires 'Perl6::Junction';
242 Note: Feel free to use "grep" in lieu of "Perl6::Junction::any" if you
244 prefer. Also, please don't let the use of the "Perl6::Junction" module
245 above lead you to believe that Catalyst is somehow dependent on Perl
246 6... we are simply using that module for its easy-to-read
247 <http://blogs.perl.org/users/marc_sebastian_jakobs/2009/11/my-favorite-
248 module-of-the-month-perl6junction.html> "any" function.
249 Now we need to add some enforcement inside our controller. Open
251 "lib/MyApp/Controller/Books.pm" and update the "delete" method to match
252 the following code:
253 =head2 delete
255 Delete a book
257 =cut
259 sub delete :Chained('object') :PathPart('delete') :Args(0) {
261 my ($self, $c) = @_;
262 # Check permissions
264 $c->detach('/error_noperms')
265 unless $c->stash->{object}->delete_allowed_by($c->user->get_object);
266 # Saved the PK id for status_msg below
268 my $id = $c->stash->{object}->id;
269 # Use the book object saved by 'object' and delete it along
271 # with related 'book_authors' entries
272 $c->stash->{object}->delete;
273 # Redirect the user back to the list page
275 $c->response->redirect($c->uri_for($self->action_for('list'),
276 {mid => $c->set_status_msg("Deleted book $id")}));
277 }
278 Here, we "detach" to an error page if the user is lacking the
280 appropriate permissions. For this to work, we need to make
281 arrangements for the '/error_noperms' action to work. Open
282 "lib/MyApp/Controller/Root.pm" and add this method:
283 =head2 error_noperms
285 Permissions error screen
287 =cut
289 sub error_noperms :Chained('/') :PathPart('error_noperms') :Args(0) {
291 my ($self, $c) = @_;
292 $c->stash(template => 'error_noperms.tt2');
294 }
295 And also add the template file by putting the following text into
297 "root/src/error_noperms.tt2":
298 <span class="error">Permission Denied</span>
300 Log in as "test01" and create several new books using the "url_create"
302 feature:
303 http://localhost:3000/books/url_create/Test/1/4
305 Then, while still logged in as "test01", click the "Delete" link next
307 to one of these books. The book should be removed and you should see
308 the usual green "Book deleted" message. Next, click the "User Logout"
309 link and log back in as "test02". Now try deleting one of the books.
310 You should be taken to the red "Permission Denied" message on our error
311 page.
312 Use one of the 'Logout' links (or go to the
314 <http://localhost:3000/logout> URL directly) when you are done.
315 You can jump to the next chapter of the tutorial here: Debugging
317
319 Kennedy Clark, "hkclark@gmail.com"
320 Feel free to contact the author for any errors or suggestions, but the
322 best way to report issues is via the CPAN RT Bug system at
323 <https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
324 Copyright 2006-2011, Kennedy Clark, under the Creative Commons
326 Attribution Share-Alike License Version 3.0
327 (<http://creativecommons.org/licenses/by-sa/3.0/us/>).
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