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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 |
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60 | existing authentication implemented in |
61 | L<Chapter 5|Catalyst::Manual::Tutorial::05_Authentication>. It provides |
62 | simple examples of how to use roles in both TT templates and controller |
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63 | actions. The first half looks at basic authorization concepts. The |
64 | second half looks at how moving your authorization code to your model |
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65 | can simplify your code and make things easier to maintain. |
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66 | |
67 | You can checkout the source code for this example from the catalyst |
68 | subversion repository as per the instructions in |
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69 | L<Catalyst::Manual::Tutorial::01_Intro>. |
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70 | |
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71 | |
72 | =head1 BASIC AUTHORIZATION |
73 | |
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74 | In this section you learn the basics of how authorization works under |
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75 | Catalyst. |
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76 | |
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77 | |
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78 | =head2 Update Plugins to Include Support for Authorization |
79 | |
80 | Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list: |
81 | |
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82 | # Load plugins |
83 | use Catalyst qw/ |
84 | -Debug |
85 | ConfigLoader |
86 | Static::Simple |
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87 | |
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88 | StackTrace |
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89 | |
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90 | Authentication |
91 | Authorization::Roles |
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92 | |
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93 | Session |
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94 | Session::Store::File |
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95 | Session::State::Cookie |
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96 | |
97 | StatusMessage |
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98 | /; |
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99 | |
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100 | Once again, include this additional plugin as a new dependency in the |
101 | Makefile.PL file like this: |
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102 | |
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103 | requires 'Catalyst::Plugin::Authorization::Roles'; |
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104 | |
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105 | |
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106 | =head2 Add Role-Specific Logic to the "Book List" Template |
107 | |
108 | Open C<root/src/books/list.tt2> in your editor and add the following |
109 | lines to the bottom of the file: |
110 | |
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111 | ... |
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112 | <p>Hello [% c.user.username %], you have the following roles:</p> |
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113 | |
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114 | <ul> |
115 | [% # Dump list of roles -%] |
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116 | [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %] |
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117 | </ul> |
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118 | |
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119 | <p> |
120 | [% # Add some simple role-specific logic to template %] |
121 | [% # Use $c->check_user_roles() to check authz -%] |
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122 | [% IF c.check_user_roles('user') %] |
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123 | [% # Give normal users a link for 'logout' %] |
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124 | <a href="[% c.uri_for('/logout') %]">User Logout</a> |
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125 | [% END %] |
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126 | |
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127 | [% # Can also use $c->user->check_roles() to check authz -%] |
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128 | [% IF c.check_user_roles('admin') %] |
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129 | [% # Give admin users a link for 'create' %] |
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130 | <a href="[% c.uri_for(c.controller.action_for('form_create')) %]">Admin Create</a> |
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131 | [% END %] |
132 | </p> |
133 | |
134 | This code displays a different combination of links depending on the |
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135 | roles assigned to the user. |
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136 | |
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137 | |
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138 | =head2 Limit Books::add to 'admin' Users |
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139 | |
140 | C<IF> statements in TT templates simply control the output that is sent |
141 | to the user's browser; it provides no real enforcement (if users know or |
142 | guess the appropriate URLs, they are still perfectly free to hit any |
143 | action within your application). We need to enhance the controller |
144 | logic to wrap restricted actions with role-validation logic. |
145 | |
146 | For example, we might want to restrict the "formless create" action to |
147 | admin-level users by editing C<lib/MyApp/Controller/Books.pm> and |
148 | updating C<url_create> to match the following code: |
149 | |
150 | =head2 url_create |
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151 | |
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152 | Create a book with the supplied title and rating, |
153 | with manual authorization |
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154 | |
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155 | =cut |
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156 | |
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157 | sub url_create :Chained('base') :PathPart('url_create') :Args(3) { |
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158 | # In addition to self & context, get the title, rating & author_id args |
159 | # from the URL. Note that Catalyst automatically puts extra information |
160 | # after the "/<controller_name>/<action_name/" into @_ |
161 | my ($self, $c, $title, $rating, $author_id) = @_; |
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162 | |
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163 | # Check the user's roles |
164 | if ($c->check_user_roles('admin')) { |
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165 | # Call create() on the book model object. Pass the table |
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166 | # columns/field values we want to set as hash values |
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167 | my $book = $c->model('DB::Book')->create({ |
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168 | title => $title, |
169 | rating => $rating |
170 | }); |
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171 | |
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172 | # Add a record to the join table for this book, mapping to |
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173 | # appropriate author |
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174 | $book->add_to_book_authors({author_id => $author_id}); |
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175 | # Note: Above is a shortcut for this: |
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176 | # $book->create_related('book_authors', {author_id => $author_id}); |
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177 | |
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178 | # Assign the Book object to the stash and set template |
179 | $c->stash(book => $book, |
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180 | template => 'books/create_done.tt2'); |
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181 | } else { |
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182 | # Provide very simple feedback to the user. |
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183 | $c->response->body('Unauthorized!'); |
184 | } |
185 | } |
186 | |
187 | |
188 | To add authorization, we simply wrap the main code of this method in an |
189 | C<if> statement that calls C<check_user_roles>. If the user does not |
190 | have the appropriate permissions, they receive an "Unauthorized!" |
191 | message. Note that we intentionally chose to display the message this |
192 | way to demonstrate that TT templates will not be used if the response |
193 | body has already been set. In reality you would probably want to use a |
194 | technique that maintains the visual continuity of your template layout |
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195 | (for example, using L<Catalyst::Plugin::StateMessage> as shown in the |
196 | L<last chapter|Catalyst::Manual::Tutorial::05_Authentication> to |
197 | redirect to an "unauthorized" page). |
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198 | |
199 | B<TIP>: If you want to keep your existing C<url_create> method, you can |
200 | create a new copy and comment out the original by making it look like a |
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201 | Pod comment. For example, put something like C<=begin> before |
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202 | C<sub add : Local {> and C<=end> after the closing C<}>. |
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203 | |
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204 | |
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205 | =head2 Try Out Authentication And Authorization |
206 | |
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207 | Make sure the development server is running: |
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208 | |
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209 | $ script/myapp_server.pl -r |
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210 | |
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211 | Now trying going to L<http://localhost:3000/books/list> and you should |
212 | be taken to the login page (you might have to C<Shift+Reload> or |
213 | C<Ctrl+Reload> your browser and/or click the "User Logout" link on the |
214 | book list page). Try logging in with both C<test01> and C<test02> (both |
215 | use a password of C<mypass>) and notice how the roles information |
216 | updates at the bottom of the "Book List" page. Also try the "User |
217 | Logout" link on the book list page. |
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218 | |
219 | Now the "url_create" URL will work if you are already logged in as user |
220 | C<test01>, but receive an authorization failure if you are logged in as |
221 | C<test02>. Try: |
222 | |
223 | http://localhost:3000/books/url_create/test/1/6 |
224 | |
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225 | while logged in as each user. Use one of the "logout" links (or go to |
226 | L<http://localhost:3000/logout> in your browser directly) when you are |
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227 | done. |
228 | |
229 | |
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230 | =head1 ENABLE MODEL-BASED AUTHORIZATION |
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231 | |
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232 | Hopefully it's fairly obvious that adding detailed permission checking |
233 | logic to our controllers and view templates isn't a very clean or |
234 | scalable way to build role-based permissions into out application. As |
235 | with many other aspects of MVC web development, the goal is to have your |
236 | controllers and views be an "thin" as possible, with all of the "fancy |
237 | business logic" built into your model. |
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238 | |
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239 | For example, let's add a method to our C<Books.pm> Result Class to check |
240 | if a user is allowed to delete a book. Open |
241 | C<lib/MyApp/Schema/Result/Book.pm> and add the following method (be sure |
242 | to add it below the "C<DO NOT MODIFY ...>" line): |
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243 | |
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244 | =head2 delete_allowed_by |
245 | |
246 | Can the specified user delete the current book? |
247 | |
248 | =cut |
249 | |
250 | sub delete_allowed_by { |
251 | my ($self, $user) = @_; |
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252 | |
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253 | # Only allow delete if user has 'admin' role |
254 | return $user->has_role('admin'); |
255 | } |
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256 | |
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257 | Here we call a C<has_role> method on our user object, so we should add |
258 | this method to our Result Class. Open |
259 | C<lib/MyApp/Schema/Result/User.pm> and add the following method below |
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260 | the "C<DO NOT MODIFY ...>" line: |
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261 | |
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262 | =head2 has_role |
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263 | |
264 | Check if a user has the specified role |
265 | |
266 | =cut |
267 | |
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268 | use Perl6::Junction qw/any/; |
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269 | sub has_role { |
270 | my ($self, $role) = @_; |
271 | |
272 | # Does this user posses the required role? |
273 | return any(map { $_->role } $self->roles) eq $role; |
274 | } |
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275 | |
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276 | Let's also add Perl6::Junction to the requirements listed in |
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277 | Makefile.PL: |
278 | |
279 | requires 'Perl6::Junction'; |
280 | |
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281 | Now we need to add some enforcement inside our controller. Open |
282 | C<lib/MyApp/Controller/Books.pm> and update the C<delete> method to |
283 | match the following code: |
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284 | |
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285 | =head2 delete |
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286 | |
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287 | Delete a book |
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288 | |
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289 | =cut |
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290 | |
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291 | sub delete :Chained('object') :PathPart('delete') :Args(0) { |
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292 | my ($self, $c) = @_; |
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293 | |
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294 | # Check permissions |
295 | $c->detach('/error_noperms') |
296 | unless $c->stash->{object}->delete_allowed_by($c->user->get_object); |
297 | |
298 | # Use the book object saved by 'object' and delete it along |
299 | # with related 'book_authors' entries |
300 | $c->stash->{object}->delete; |
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301 | |
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302 | # Use 'flash' to save information across requests until it's read |
303 | $c->flash->{status_msg} = "Book deleted"; |
304 | |
305 | # Redirect the user back to the list page |
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306 | $c->response->redirect($c->uri_for($self->action_for('list'), |
307 | {mid => $c->set_status_msg("Deleted book $id")})); |
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308 | } |
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309 | |
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310 | Here, we C<detach> to an error page if the user is lacking the |
311 | appropriate permissions. For this to work, we need to make arrangements |
312 | for the '/error_noperms' action to work. Open |
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313 | C<lib/MyApp/Controller/Root.pm> and add this method: |
314 | |
315 | =head2 error_noperms |
316 | |
317 | Permissions error screen |
318 | |
319 | =cut |
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320 | |
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321 | sub error_noperms :Chained('/') :PathPart('error_noperms') :Args(0) { |
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322 | my ($self, $c) = @_; |
323 | |
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324 | $c->stash(template => 'error_noperms.tt2'); |
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325 | } |
326 | |
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327 | And also add the template file by putting the following text into |
328 | C<root/src/error_noperms.tt2>: |
329 | |
330 | <span class="error">Permission Denied</span> |
331 | |
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332 | Log in as C<test01> and create several new books using the C<url_create> |
333 | feature: |
334 | |
335 | http://localhost:3000/books/url_create/Test/1/4 |
336 | |
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337 | Then, while still logged in as C<test01>, click the "Delete" link next |
338 | to one of these books. The book should be removed and you should see |
339 | the usual green "Book deleted" message. Next, click the "User Logout" |
340 | link and log back in as C<test02>. Now try deleting one of the books. |
341 | You should be taken to the red "Permission Denied" message on our error |
342 | page. |
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343 | |
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344 | Use one of the 'Logout' links (or go to the |
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345 | L<http://localhost:3000/logout> URL directly) when you are done. |
346 | |
347 | |
348 | =head1 AUTHOR |
349 | |
350 | Kennedy Clark, C<hkclark@gmail.com> |
351 | |
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352 | Feel free to contact the author for any errors or suggestions, but the |
353 | best way to report issues is via the CPAN RT Bug system at |
354 | <https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>. |
355 | |
356 | The most recent version of the Catalyst Tutorial can be found at |
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357 | L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>. |
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358 | |
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359 | Copyright 2006-2010, Kennedy Clark, under the |
360 | Creative Commons Attribution Share-Alike License Version 3.0 |
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361 | (L<http://creativecommons.org/licenses/by-sa/3.0/us/>). |