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1 | =head1 NAME |
2 | |
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3 | Catalyst::Manual::Tutorial::BasicCRUD - Catalyst Tutorial - Part 3: Basic CRUD |
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4 | |
5 | |
6 | =head1 OVERVIEW |
7 | |
8 | This is B<Part 3 of 9> for the Catalyst tutorial. |
9 | |
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10 | L<Tutorial Overview|Catalyst::Manual::Tutorial> |
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11 | |
12 | =over 4 |
13 | |
14 | =item 1 |
15 | |
16 | L<Introduction|Catalyst::Manual::Tutorial::Intro> |
17 | |
18 | =item 2 |
19 | |
20 | L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics> |
21 | |
22 | =item 3 |
23 | |
24 | B<Basic CRUD> |
25 | |
26 | =item 4 |
27 | |
28 | L<Authentication|Catalyst::Manual::Tutorial::Authentication> |
29 | |
30 | =item 5 |
31 | |
32 | L<Authorization|Catalyst::Manual::Tutorial::Authorization> |
33 | |
34 | =item 6 |
35 | |
36 | L<Debugging|Catalyst::Manual::Tutorial::Debugging> |
37 | |
38 | =item 7 |
39 | |
40 | L<Testing|Catalyst::Manual::Tutorial::Testing> |
41 | |
42 | =item 8 |
43 | |
44 | L<AdvancedCRUD|Catalyst::Manual::Tutorial::AdvancedCRUD> |
45 | |
46 | =item 9 |
47 | |
48 | L<Appendicies|Catalyst::Manual::Tutorial::Appendicies> |
49 | |
50 | =back |
51 | |
52 | |
53 | |
54 | =head1 DESCRIPTION |
55 | |
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56 | This part of the tutorial builds on the fairly primitive application |
57 | created in Part 2 to add basic support for Create, Read, Update, and |
58 | Delete (CRUD) of C<Book> objects. Note that the 'list' function in Part |
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59 | 2 already implements the Read portion of CRUD (although Read normally |
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60 | refers to reading a single object; you could implement full read |
61 | functionality using the techniques introduced below). This section will |
62 | focus on the Create and Delete aspects of CRUD. More advanced |
63 | capabilities, including full Update functionality, will be addressed in |
64 | Part 8. |
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65 | |
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66 | B<TIP>: Note that all of the code for this part of the tutorial can be |
67 | pulled from the Catalyst Subversion repository in one step with the |
68 | following command: |
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69 | |
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70 | svn checkout http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/Tutorial -r 4611 . |
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71 | |
72 | |
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73 | =head1 FORMLESS SUBMISSION |
74 | |
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75 | Our initial attempt at object creation will utilize the "URL arguments" |
76 | feature of Catalyst (we will employ the more common form-based |
77 | submission in the sections that follow). |
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78 | |
79 | |
80 | =head2 Include a Create Action in the Books Controller |
81 | |
82 | Edit C<lib/MyApp/Controller/Books.pm> and enter the following method: |
83 | |
84 | =head2 url_create |
85 | |
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86 | Create a book with the supplied title, rating, and author |
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87 | |
88 | =cut |
89 | |
90 | sub url_create : Local { |
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91 | # In addition to self & context, get the title, rating, & |
92 | # author_id args from the URL. Note that Catalyst automatically |
93 | # puts extra information after the "/<controller_name>/<action_name/" |
94 | # into @_ |
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95 | my ($self, $c, $title, $rating, $author_id) = @_; |
96 | |
97 | # Call create() on the book model object. Pass the table |
98 | # columns/field values we want to set as hash values |
99 | my $book = $c->model('MyAppDB::Book')->create({ |
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100 | title => $title, |
101 | rating => $rating |
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102 | }); |
103 | |
104 | # Add a record to the join table for this book, mapping to |
105 | # appropriate author |
106 | $book->add_to_book_authors({author_id => $author_id}); |
107 | # Note: Above is a shortcut for this: |
108 | # $book->create_related('book_authors', {author_id => $author_id}); |
109 | |
110 | # Assign the Book object to the stash for display in the view |
111 | $c->stash->{book} = $book; |
112 | |
113 | # This is a hack to disable XSUB processing in Data::Dumper |
114 | # (it's used in the view). This is a work-around for a bug in |
115 | # the interaction of some versions or Perl, Data::Dumper & DBIC. |
116 | # You won't need this if you aren't using Data::Dumper (or if |
117 | # you are running DBIC 0.06001 or greater), but adding it doesn't |
118 | # hurt anything either. |
119 | $Data::Dumper::Useperl = 1; |
120 | |
121 | # Set the TT template to use |
122 | $c->stash->{template} = 'books/create_done.tt2'; |
123 | } |
124 | |
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125 | Notice that Catalyst takes "extra slash-separated information" from the |
126 | URL and passes it as arguments in C<@_>. The C<url_create> action then |
127 | uses a simple call to the DBIC C<create> method to add the requested |
128 | information to the database (with a separate call to |
129 | C<add_to_book_authors> to update the join table). As do virtually all |
130 | controller methods (at least the ones that directly handle user input), |
131 | it then sets the template that should handle this request. |
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132 | |
133 | |
134 | =head2 Include a Template for the C<url_create> Action: |
135 | |
136 | Edit C<root/src/books/create_done.tt2> and then enter: |
137 | |
138 | [% # Use the TT Dumper plugin to Data::Dumper variables to the browser -%] |
139 | [% # Not a good idea for production use, though. :-) 'Indent=1' is -%] |
140 | [% # optional, but prevents "massive indenting" of deeply nested objects -%] |
141 | [% USE Dumper(Indent=1) -%] |
142 | |
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143 | [% # Set the page title. META can 'go back' and set values in templates -%] |
144 | [% # that have been processed 'before' this template (here it's for -%] |
145 | [% # root/lib/site/html and root/lib/site/header). Note that META on -%] |
146 | [% # simple strings (e.g., no variable interpolation). -%] |
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147 | [% META title = 'Book Created' %] |
148 | |
149 | [% # Output information about the record that was added. Note use -%] |
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150 | [% # of 'first' to only list the first author (if > 1 author). TT -%] |
151 | [% # v2.15 has an issue that requires -%] |
152 | [% # 'book.authors.list.first.value.last_name' vs. the shorter -%] |
153 | [% # 'book.authors.first.last_name' in prior versions. -%] |
154 | <p>Added book '[% book.title %]' |
155 | by '[% book.authors.list.first.value.last_name %]' |
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156 | with a rating of [% book.rating %].</p> |
157 | |
158 | [% # Provide a link back to the list page -%] |
159 | [% # 'uri_for()' builds a full URI; e.g., 'http://localhost:3000/books/list' -%] |
160 | <p><a href="[% Catalyst.uri_for('/books/list') %]">Return to list</a></p> |
161 | |
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162 | [% # Try out the TT Dumper (for development only!) -%] |
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163 | <pre> |
164 | Dump of the 'book' variable: |
165 | [% Dumper.dump(book) %] |
166 | </pre> |
167 | |
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168 | The TT C<USE> directive allows access to a variety of plugin modules (TT |
169 | plugins, that is, not Catalyst plugins) to add extra functionality to |
170 | the base TT capabilities. Here, the plugin allows L<Data::Dumper> |
171 | "pretty printing" of objects and variables. Other than that, the rest |
172 | of the code should be familiar from the examples in Part 2. |
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173 | |
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174 | B<IMPORTANT NOTE> As mentioned earlier, the C<MyApp::View::TT.pm> view |
175 | class created by TTSite redefines the name used to access the Catalyst |
176 | context object in TT templates from the usual C<c> to C<Catalyst>. |
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177 | |
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178 | =head2 Try the C<url_create> Feature |
179 | |
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180 | If the application is still running from before, use C<Ctrl-C> to kill |
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181 | it. Then restart the server: |
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182 | |
183 | $ script/myapp_server.pl |
184 | |
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185 | Note that new path for C</books/url_create> appears in the startup debug |
186 | output. |
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187 | |
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188 | B<TIP>: You can use C<script/myapp_server.pl -r> to have the development |
189 | server auto-detect changed files and reload itself (if your browser acts |
190 | odd, you should also try throwing in a C<-k>). If you make changes to |
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191 | the TT templates only, you do not need to reload the development server |
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192 | (only changes to "compiled code" such as Controller and Model C<.pm> |
193 | files require a reload). |
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194 | |
195 | Next, use your browser to enter the following URL: |
196 | |
197 | http://localhost:3000/books/url_create/TCPIP_Illustrated_Vol-2/5/4 |
198 | |
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199 | Your browser should display " Added book 'TCPIP_Illustrated_Vol-2' by |
200 | 'Stevens' with a rating of 5." along with a dump of the new book model |
201 | object. You should also see the following DBIC debug messages displayed |
202 | in the development server log messages: |
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203 | |
204 | INSERT INTO books (rating, title) VALUES (?, ?): `5', `TCPIP_Illustrated_Vol-2' |
205 | INSERT INTO book_authors (author_id, book_id) VALUES (?, ?): `4', `6' |
206 | |
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207 | If you then click the "Return to list" link, you should find that there |
208 | are now six books shown (if necessary, Shift-Reload your browser at the |
209 | C</books/list> page). |
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210 | |
211 | |
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212 | =head1 MANUALLY BUILDING A CREATE FORM |
213 | |
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214 | Although the C<url_create> action in the previous step does begin to |
215 | reveal the power and flexibility of both Catalyst and DBIC, it's |
216 | obviously not a very realistic example of how users should be expected |
217 | to enter data. This section begins to address that concern. |
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218 | |
219 | |
220 | =head2 Add Method to Display The Form |
221 | |
222 | Edit C<lib/MyApp/Controller/Books.pm> and add the following method: |
223 | |
224 | =head2 form_create |
225 | |
226 | Display form to collect information for book to create |
227 | |
228 | =cut |
229 | |
230 | sub form_create : Local { |
231 | my ($self, $c) = @_; |
232 | |
233 | # Set the TT template to use |
234 | $c->stash->{template} = 'books/form_create.tt2'; |
235 | } |
236 | |
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237 | This action simply invokes a view containing a book creation form. |
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238 | |
239 | =head2 Add a Template for the Form |
240 | |
241 | Open C<root/src/books/form_create.tt2> in your editor and enter: |
242 | |
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243 | [% META title = 'Manual Form Book Create' -%] |
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244 | |
245 | <form method="post" action="[% Catalyst.uri_for('form_create_do') %]"> |
246 | <table> |
247 | <tr><td>Title:</td><td><input type="text" name="title"></td></tr> |
248 | <tr><td>Rating:</td><td><input type="text" name="rating"></td></tr> |
249 | <tr><td>Author ID:</td><td><input type="text" name="author_id"></td></tr> |
250 | </table> |
251 | <input type="submit" name="Submit" value="Submit"> |
252 | </form> |
253 | |
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254 | Note that we have specified the target of the form data as |
255 | C<form_create_do>, the method created in the section that follows. |
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256 | |
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257 | =head2 Add Method to Process Form Values and Update Database |
258 | |
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259 | Edit C<lib/MyApp/Controller/Books.pm> and add the following method to |
260 | save the form information to the databse: |
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261 | |
262 | =head2 form_create_do |
263 | |
264 | Take information from form and add to database |
265 | |
266 | =cut |
267 | |
268 | sub form_create_do : Local { |
269 | my ($self, $c) = @_; |
270 | |
271 | # Retrieve the values from the form |
272 | my $title = $c->request->params->{title} || 'N/A'; |
273 | my $rating = $c->request->params->{rating} || 'N/A'; |
274 | my $author_id = $c->request->params->{author_id} || '1'; |
275 | |
276 | # Create the book |
277 | my $book = $c->model('MyAppDB::Book')->create({ |
278 | title => $title, |
279 | rating => $rating, |
280 | }); |
281 | # Handle relationship with author |
282 | $book->add_to_book_authors({author_id => $author_id}); |
283 | |
284 | # Store new model object in stash |
285 | $c->stash->{book} = $book; |
286 | |
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287 | # Avoid Data::Dumper issue mentioned earlier |
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288 | # You can probably omit this |
289 | $Data::Dumper::Useperl = 1; |
290 | |
291 | # Set the TT template to use |
292 | $c->stash->{template} = 'books/create_done.tt2'; |
293 | } |
294 | |
295 | |
296 | =head2 Test Out The Form |
297 | |
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298 | If the application is still running from before, use C<Ctrl-C> to kill |
299 | it. Then restart the server: |
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300 | |
301 | $ script/myapp_server.pl |
302 | |
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303 | Point your browser to L<http://localhost:3000/books/form_create> and |
304 | enter "TCP/IP Illustrated, Vol 3" for the title, a rating of 5, and an |
305 | author ID of 4. You should then be forwarded to the same |
306 | C<create_done.tt2> template seen in earlier examples. Finally, click |
307 | "Return to list" to view the full list of books. |
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308 | |
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309 | B<Note:> Having the user enter the primary key ID for the author is |
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310 | obviously crude; we will address this concern with a drop-down list in |
311 | Part 8. |
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312 | |
313 | =head1 A SIMPLE DELETE FEATURE |
314 | |
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315 | Turning out attention to the delete portion of CRUD, this section |
316 | illustrates some basic techniques that can be used to remove information |
317 | from the database. |
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318 | |
319 | |
320 | =head2 Include a Delete Link in the List |
321 | |
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322 | Edit C<root/src/books/list.tt2> and update it to the following (two |
323 | sections have changed: 1) the additional '<th>Links</th>' table header, |
324 | and 2) the four lines for the Delete link near the bottom). |
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325 | |
326 | [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%] |
327 | [% # see this "chomping" in your browser because HTML ignores blank lines, but -%] |
328 | [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%] |
329 | [%- # optional, but both the beginning and the ending TT tags support chomping. -%] |
330 | |
331 | [% # Provide a title to root/lib/site/header -%] |
332 | [% META title = 'Book List' -%] |
333 | |
334 | <table> |
335 | <tr><th>Title</th><th>Rating</th><th>Author(s)</th><th>Links</th></tr> |
336 | [% # Display each book in a table row %] |
337 | [% FOREACH book IN books -%] |
338 | <tr> |
339 | <td>[% book.title %]</td> |
340 | <td>[% book.rating %]</td> |
341 | <td> |
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342 | [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%] |
343 | [% # loop in 'side effect notation' to load just the last names of the -%] |
344 | [% # authors into the list. Note that we are making a bogus assignment to -%] |
345 | [% # the 'xx' vbl to avoid printing the size of the list after each push. -%] |
346 | [% tt_authors = [ ]; |
347 | xx = tt_authors.push(author.last_name) FOREACH author = book.authors %] |
348 | [% # Now use a TT 'virtual method' to display the author count -%] |
349 | ([% tt_authors.size %]) |
350 | [% # Use another TT virtual method to join the names with comma separators -%] |
351 | [% tt_authors.join(', ') %] |
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352 | </td> |
353 | <td> |
354 | [% # Add a link to delete a book %] |
355 | <a href="[% Catalyst.uri_for('delete/') _ book.id %]">Delete</a> |
356 | </td> |
357 | </tr> |
358 | [% END -%] |
359 | </table> |
360 | |
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361 | The additional code is obviously designed to add a new column to the |
362 | right side of the table with a C<Delete> "button" (for simplicity, links |
363 | will be used instead of full HTML buttons). |
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364 | |
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365 | =head2 Add a Delete Action to the Controller |
366 | |
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367 | Open C<lib/MyApp/Controller/Books.pm> in your editor and add the |
368 | following method: |
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369 | |
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370 | =head2 delete |
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371 | |
372 | Delete a book |
373 | |
374 | =cut |
375 | |
376 | sub delete : Local { |
377 | # $id = primary key of book to delete |
378 | my ($self, $c, $id) = @_; |
379 | |
380 | # Search for the book and then delete it |
381 | $c->model('MyAppDB::Book')->search({id => $id})->delete_all; |
382 | |
383 | # Set a status message to be displayed at the top of the view |
384 | $c->stash->{status_msg} = "Book deleted."; |
385 | |
386 | # Forward to the list action/method in this controller |
387 | $c->forward('list'); |
388 | } |
389 | |
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390 | This method first deletes the book with the specified primary key ID. |
391 | However, it also removes the corresponding entry from the |
392 | C<book_authors> table. Note that C<delete_all> was used instead of |
393 | C<delete>: whereas C<delete_all> also removes the join table entries in |
394 | C<book_authors>, C<delete> does not. |
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395 | |
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396 | Then, rather than forwarding to a "delete done" page as we did with the |
397 | earlier create example, it simply sets the C<status_msg> to display a |
398 | notification to the user as the normal list view is rendered. |
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399 | |
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400 | The C<delete> action uses the context C<forward> method to return the |
401 | user to the book list. The C<detach> method could have also been used. |
402 | Whereas C<forward> I<returns> to the original action once it is |
403 | completed, C<detach> does I<not> return. Other than that, the two are |
404 | equivalent. |
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405 | |
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406 | Another alternative to C<forward> would be to use |
407 | C<$c-E<gt>response-E<gt>redirect($c-E<gt>uri_for('/books/list'))>. The |
408 | C<forward> and C<redirect> operations differ in several important |
409 | respects that stem from the fact that redirects cause the client browser |
410 | to issue an entirely new HTTP request. In doing so, this results in a |
411 | new URL showing in the browser window. And, because the stash |
412 | information is reset for every request, the "Book deleted" message would |
413 | not be displayed. |
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414 | |
415 | |
416 | =head2 Try the Delete Feature |
417 | |
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418 | If the application is still running from before, use C<Ctrl-C> to kill |
419 | it. Then restart the server: |
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420 | |
421 | $ script/myapp_server.pl |
422 | |
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423 | Then point your browser to L<http://localhost:3000/books/list> and click |
424 | the "Delete" link next to "TCPIP_Illustrated_Vol-2". A green "Book |
425 | deleted" status message should display at the top of the page, along |
426 | with a list of the six remaining books. |
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427 | |
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428 | |
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429 | =head1 AUTHOR |
430 | |
431 | Kennedy Clark, C<hkclark@gmail.com> |
432 | |
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433 | Please report any errors, issues or suggestions to the author. The |
434 | most recent version of the Catlayst Tutorial can be found at |
435 | L<http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Runtime/lib/Catalyst/Manual/Tutorial/>. |
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436 | |
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437 | Copyright 2006, Kennedy Clark, under Creative Commons License |
438 | (L<http://creativecommons.org/licenses/by-nc-sa/2.5/>). |
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439 | |