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1 | =head1 NAME |
2 | |
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3 | Catalyst::Manual::Tutorial::06_Authorization - Catalyst Tutorial - Chapter 6: Authorization |
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4 | |
5 | |
6 | =head1 OVERVIEW |
7 | |
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8 | This is B<Chapter 6 of 10> for the Catalyst tutorial. |
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9 | |
10 | L<Tutorial Overview|Catalyst::Manual::Tutorial> |
11 | |
12 | =over 4 |
13 | |
14 | =item 1 |
15 | |
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16 | L<Introduction|Catalyst::Manual::Tutorial::01_Intro> |
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17 | |
18 | =item 2 |
19 | |
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20 | L<Catalyst Basics|Catalyst::Manual::Tutorial::02_CatalystBasics> |
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21 | |
22 | =item 3 |
23 | |
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24 | L<More Catalyst Basics|Catalyst::Manual::Tutorial::03_MoreCatalystBasics> |
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25 | |
26 | =item 4 |
27 | |
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28 | L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD> |
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29 | |
30 | =item 5 |
31 | |
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32 | L<Authentication|Catalyst::Manual::Tutorial::05_Authentication> |
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33 | |
34 | =item 6 |
35 | |
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36 | B<06_Authorization> |
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37 | |
38 | =item 7 |
39 | |
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40 | L<Debugging|Catalyst::Manual::Tutorial::07_Debugging> |
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41 | |
42 | =item 8 |
43 | |
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44 | L<Testing|Catalyst::Manual::Tutorial::08_Testing> |
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45 | |
46 | =item 9 |
47 | |
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48 | L<Advanced CRUD|Catalyst::Manual::Tutorial::09_AdvancedCRUD> |
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49 | |
50 | =item 10 |
51 | |
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52 | L<Appendices|Catalyst::Manual::Tutorial::10_Appendices> |
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53 | |
54 | =back |
55 | |
56 | |
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57 | =head1 DESCRIPTION |
58 | |
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59 | This chapter of the tutorial adds role-based authorization to the |
60 | existing authentication implemented in Chapter 5. It provides simple |
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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. |
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65 | |
66 | You can checkout the source code for this example from the catalyst |
67 | subversion repository as per the instructions in |
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68 | L<Catalyst::Manual::Tutorial::01_Intro|Catalyst::Manual::Tutorial::01_Intro>. |
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69 | |
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70 | |
71 | =head1 BASIC AUTHORIZATION |
72 | |
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73 | In this section you learn the basics of how authorization works under |
74 | Catalyst. |
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75 | |
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76 | |
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77 | =head2 Update Plugins to Include Support for Authorization |
78 | |
79 | Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list: |
80 | |
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81 | # Load plugins |
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82 | use Catalyst qw/ |
83 | -Debug |
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84 | ConfigLoader |
85 | Static::Simple |
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86 | |
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87 | StackTrace |
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88 | |
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89 | Authentication |
90 | Authorization::Roles |
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91 | |
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92 | Session |
93 | Session::Store::FastMmap |
94 | Session::State::Cookie |
95 | /; |
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96 | |
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97 | Once again, include this additional plugin as a new dependency in |
98 | the Makefile.PL file like this: |
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99 | |
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100 | requires 'Catalyst::Plugin::Authorization::Roles'; |
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101 | |
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102 | |
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103 | =head2 Add Role-Specific Logic to the "Book List" Template |
104 | |
105 | Open C<root/src/books/list.tt2> in your editor and add the following |
106 | lines to the bottom of the file: |
107 | |
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108 | ... |
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109 | <p>Hello [% c.user.username %], you have the following roles:</p> |
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110 | |
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111 | <ul> |
112 | [% # Dump list of roles -%] |
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113 | [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %] |
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114 | </ul> |
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115 | |
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116 | <p> |
117 | [% # Add some simple role-specific logic to template %] |
118 | [% # Use $c->check_user_roles() to check authz -%] |
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119 | [% IF c.check_user_roles('user') %] |
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120 | [% # Give normal users a link for 'logout' %] |
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121 | <a href="[% c.uri_for('/logout') %]">User Logout</a> |
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122 | [% END %] |
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123 | |
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124 | [% # Can also use $c->user->check_roles() to check authz -%] |
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125 | [% IF c.check_user_roles('admin') %] |
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126 | [% # Give admin users a link for 'create' %] |
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127 | <a href="[% c.uri_for(c.controller.action_for('form_create')) %]">Admin Create</a> |
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128 | [% END %] |
129 | </p> |
130 | |
131 | This code displays a different combination of links depending on the |
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132 | roles assigned to the user. |
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133 | |
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134 | |
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135 | =head2 Limit Books::add to 'admin' Users |
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136 | |
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. |
142 | |
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: |
146 | |
147 | =head2 url_create |
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148 | |
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149 | Create a book with the supplied title and rating, |
150 | with manual authorization |
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151 | |
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152 | =cut |
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153 | |
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154 | sub url_create :Chained('base') :PathPart('url_create') :Args(3) { |
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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, $author_id) = @_; |
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159 | |
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160 | # Check the user's roles |
161 | if ($c->check_user_roles('admin')) { |
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162 | # Call create() on the book model object. Pass the table |
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163 | # columns/field values we want to set as hash values |
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164 | my $book = $c->model('DB::Book')->create({ |
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165 | title => $title, |
166 | rating => $rating |
167 | }); |
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168 | |
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169 | # Add a record to the join table for this book, mapping to |
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170 | # appropriate author |
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171 | $book->add_to_book_authors({author_id => $author_id}); |
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172 | # Note: Above is a shortcut for this: |
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173 | # $book->create_related('book_authors', {author_id => $author_id}); |
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174 | |
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175 | # Assign the Book object to the stash for display in the view |
176 | $c->stash->{book} = $book; |
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177 | |
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178 | # Set the TT template to use |
179 | $c->stash->{template} = 'books/create_done.tt2'; |
180 | } else { |
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181 | # Provide very simple feedback to the user. |
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182 | $c->response->body('Unauthorized!'); |
183 | } |
184 | } |
185 | |
186 | |
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 |
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195 | Chapter 3 or C<detach> to an action that shows an "unauthorized" page). |
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196 | |
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 |
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199 | Pod comment. For example, put something like C<=begin> before |
200 | C<sub add : Local {> and C<=end> after the closing C<}>. |
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201 | |
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202 | |
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203 | =head2 Try Out Authentication And Authorization |
204 | |
205 | Press C<Ctrl-C> to kill the previous server instance (if it's still |
206 | running) and restart it: |
207 | |
208 | $ script/myapp_server.pl |
209 | |
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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 |
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212 | C<Ctrl+Reload> your browser and/or click the "User Logout" link on the book |
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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 |
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215 | updates at the bottom of the "Book List" page. Also try the "User Logout" |
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216 | link on the book list page. |
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217 | |
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 |
220 | C<test02>. Try: |
221 | |
222 | http://localhost:3000/books/url_create/test/1/6 |
223 | |
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224 | while logged in as each user. Use one of the "logout" links (or go to |
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225 | L<http://localhost:3000/logout> in your browser directly) when you are |
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226 | done. |
227 | |
228 | |
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229 | =head1 ENABLE MODEL-BASED AUTHORIZATION |
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230 | |
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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. |
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237 | |
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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 |
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240 | C<lib/MyApp/Schema/Result/Book.pm> and add the following method |
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241 | (be sure to add it below the "C<DO NOT MODIFY ...>" line): |
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242 | |
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243 | =head2 delete_allowed_by |
244 | |
245 | Can the specified user delete the current book? |
246 | |
247 | =cut |
248 | |
249 | sub delete_allowed_by { |
250 | my ($self, $user) = @_; |
251 | |
252 | # Only allow delete if user has 'admin' role |
253 | return $user->has_role('admin'); |
254 | } |
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255 | |
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256 | Here we call a C<has_role> method on our user object, so we should add |
257 | this method to our Result Class. Open |
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258 | C<lib/MyApp/Schema/Result/User.pm> and add the following method below |
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259 | the "C<DO NOT MODIFY ...>" line: |
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260 | |
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261 | =head 2 has_role |
262 | |
263 | Check if a user has the specified role |
264 | |
265 | =cut |
266 | |
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267 | use Perl6::Junction qw/any/; |
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268 | sub has_role { |
269 | my ($self, $role) = @_; |
270 | |
271 | # Does this user posses the required role? |
272 | return any(map { $_->role } $self->roles) eq $role; |
273 | } |
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274 | |
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275 | Now we need to add some enforcement inside our controller. Open |
276 | C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to |
277 | match the following code: |
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278 | |
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279 | =head2 delete |
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280 | |
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281 | Delete a book |
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282 | |
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283 | =cut |
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284 | |
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285 | sub delete :Chained('object') :PathPart('delete') :Args(0) { |
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286 | my ($self, $c) = @_; |
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287 | |
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288 | # Check permissions |
289 | $c->detach('/error_noperms') |
290 | unless $c->stash->{object}->delete_allowed_by($c->user->get_object); |
291 | |
292 | # Use the book object saved by 'object' and delete it along |
293 | # with related 'book_authors' entries |
294 | $c->stash->{object}->delete; |
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295 | |
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296 | # Use 'flash' to save information across requests until it's read |
297 | $c->flash->{status_msg} = "Book deleted"; |
298 | |
299 | # Redirect the user back to the list page |
300 | $c->response->redirect($c->uri_for($self->action_for('list'))); |
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301 | } |
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302 | |
303 | Here, we C<detach> to an error page if the user is lacking the |
304 | appropriate permissions. For this to work, we need to make |
305 | arrangements for the '/error_noperms' action to work. Open |
306 | C<lib/MyApp/Controller/Root.pm> and add this method: |
307 | |
308 | =head2 error_noperms |
309 | |
310 | Permissions error screen |
311 | |
312 | =cut |
313 | |
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314 | sub error_noperms :Chained('/') :PathPart('error_noperms') :Args(0) { |
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315 | my ($self, $c) = @_; |
316 | |
317 | $c->stash->{template} = 'error_noperms.tt2'; |
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318 | } |
319 | |
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320 | And also add the template file by putting the following text into |
321 | C<root/src/error_noperms.tt2>: |
322 | |
323 | <span class="error">Permission Denied</span> |
324 | |
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325 | Then run the Catalyst development server script: |
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326 | |
327 | $ script/myapp_server.pl |
328 | |
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329 | Log in as C<test01> and create several new books using the C<url_create> |
330 | feature: |
331 | |
332 | http://localhost:3000/books/url_create/Test/1/4 |
333 | |
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 |
339 | error page. |
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340 | |
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341 | Use one of the 'Logout' links (or go to the |
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342 | L<http://localhost:3000/logout> URL directly) when you are done. |
343 | |
344 | |
345 | =head1 AUTHOR |
346 | |
347 | Kennedy Clark, C<hkclark@gmail.com> |
348 | |
349 | Please report any errors, issues or suggestions to the author. The |
350 | most recent version of the Catalyst Tutorial can be found at |
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351 | L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>. |
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352 | |
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353 | Copyright 2006-2008, Kennedy Clark, under Creative Commons License |
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354 | (L<http://creativecommons.org/licenses/by-sa/3.0/us/>). |
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355 | |