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1 | =head1 NAME |
2 | |
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3 | Catalyst::Manual::Tutorial::AdvancedCRUD - Catalyst Tutorial - Part 8: Advanced CRUD |
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4 | |
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5 | =head1 OVERVIEW |
6 | |
7 | This is B<Part 8 of 9> for the Catalyst tutorial. |
8 | |
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9 | L<Tutorial Overview|Catalyst::Manual::Tutorial> |
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10 | |
11 | =over 4 |
12 | |
13 | =item 1 |
14 | |
15 | L<Introduction|Catalyst::Manual::Tutorial::Intro> |
16 | |
17 | =item 2 |
18 | |
19 | L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics> |
20 | |
21 | =item 3 |
22 | |
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23 | L<Basic CRUD|Catalyst::Manual::Tutorial_BasicCRUD> |
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24 | |
25 | =item 4 |
26 | |
27 | L<Authentication|Catalyst::Manual::Tutorial::Authentication> |
28 | |
29 | =item 5 |
30 | |
31 | L<Authorization|Catalyst::Manual::Tutorial::Authorization> |
32 | |
33 | =item 6 |
34 | |
35 | L<Debugging|Catalyst::Manual::Tutorial::Debugging> |
36 | |
37 | =item 7 |
38 | |
39 | L<Testing|Catalyst::Manual::Tutorial::Testing> |
40 | |
41 | =item 8 |
42 | |
43 | B<AdvancedCRUD> |
44 | |
45 | =item 9 |
46 | |
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47 | L<Appendices|Catalyst::Manual::Tutorial::Appendices> |
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48 | |
49 | =back |
50 | |
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51 | =head1 DESCRIPTION |
52 | |
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53 | This part of the tutorial explores more advanced functionality for |
54 | Create, Read, Update, and Delete (CRUD) than we saw in Part 3. In |
55 | particular, it looks at a number of techniques that can be useful for |
56 | the Update portion of CRUD, such as automated form generation, |
57 | validation of user-entered data, and automated transfer of data between |
58 | forms and model objects. |
59 | |
60 | In keeping with the Catalyst (and Perl) spirit of flexibility, there are |
61 | many different ways approach advanced CRUD operations in a Catalyst |
62 | environment. One alternative is to use |
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63 | L<Catalyst::Helper::Controller::Scaffold> to instantly construct a set |
64 | of Controller methods and templates for basic CRUD operations. Although |
65 | a popular subject in Quicktime movies that serve as promotional material |
66 | for various frameworks, more real-world applications require more |
67 | control. Other options include L<Data::FormValidator> and |
68 | L<HTML::FillInForm>. |
69 | |
70 | Here, we will make use of the L<HTML::Widget> to not only ease form |
71 | creation, but to also provide validation of the submitted data. The |
72 | approached used by the part of the tutorial is to slowly incorporate |
73 | additional L<HTML::Widget> functionality in a step-wise fashion (we |
74 | start with fairly simple form creation and then move on to more complex |
75 | and "magical" features such as validation and |
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76 | auto-population/auto-saving). |
77 | |
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78 | B<Note:> Part 8 of the tutorial is optional. Users who do not wish to |
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79 | use L<HTML::Widget|HTML::Widget> may skip this section. |
80 | |
81 | B<TIP>: Note that all of the code for this part of the tutorial can be |
82 | pulled from the Catalyst Subversion repository in one step with the |
83 | following command: |
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84 | |
85 | svn checkout http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/Tutorial@### |
86 | IMPORTANT: Does not work yet. Will be completed for final version. |
87 | |
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88 | =head1 C<HTML::WIDGET> FORM CREATION |
89 | |
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90 | This section looks at how L<HTML::Widget> can be used to |
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91 | add additional functionality to the manually created form from Part 3. |
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92 | |
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93 | =head2 Add the C<HTML::Widget> Plugin |
94 | |
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95 | Open C<lib/MyApp.pm> in your editor and add the following to the list of |
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96 | plugins (be sure to leave the existing plugins enabled): |
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97 | |
98 | HTML::Widget |
99 | |
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100 | =head2 Add a Form Creation Helper Method |
101 | |
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102 | Open C<lib/MyApp/Controller/Books.pm> in your editor and add the |
103 | following method: |
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104 | |
105 | =head2 make_book_widget |
106 | |
107 | Build an HTML::Widget form for book creation and updates |
108 | |
109 | =cut |
110 | |
111 | sub make_book_widget { |
112 | my ($self, $c) = @_; |
113 | |
114 | # Create an HTML::Widget to build the form |
115 | my $w = $c->widget('book_form')->method('post'); |
116 | |
117 | # Get authors |
118 | my @authorObjs = $c->model("MyAppDB::Author")->all(); |
119 | my @authors = map {$_->id => $_->last_name } |
120 | sort {$a->last_name cmp $b->last_name} @authorObjs; |
121 | |
122 | # Create the form feilds |
123 | $w->element('Textfield', 'title' )->label('Title')->size(60); |
124 | $w->element('Textfield', 'rating' )->label('Rating')->size(1); |
125 | $w->element('Select', 'authors')->label('Authors') |
126 | ->options(@authors); |
127 | $w->element('Submit', 'submit' )->value('submit'); |
128 | |
129 | # Return the widget |
130 | return $w; |
131 | } |
132 | |
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133 | This method provides a central location (so it can be called by multiple |
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134 | actions, such as C<create> and C<edit>) that builds an HTML::Wiget-based |
135 | form with the appropriate fields. The "Get Authors" code uses DBIC to |
136 | retrieve a list of model objects and then uses C<map> to create a hash |
137 | where the hash keys are the database primary keys from the authors table |
138 | and the associated values are the last names of the authors. |
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139 | |
140 | =head2 Add Actions to Display and Save the Form |
141 | |
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142 | Open C<lib/MyApp/Controller/Books.pm> in your editor and add the |
143 | following methods: |
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144 | |
145 | =head2 hw_create |
146 | |
147 | Build an HTML::Widget form for book creation and updates |
148 | |
149 | =cut |
150 | |
151 | sub hw_create : Local { |
152 | my ($self, $c) = @_; |
153 | |
154 | # Create the widget and set the action for the form |
155 | my $w = $self->make_book_widget($c); |
156 | $w->action($c->uri_for('hw_create_do')); |
157 | |
158 | # Write form to stash variable for use in template |
159 | $c->stash->{widget_result} = $w->result; |
160 | |
161 | # Set the template |
162 | $c->stash->{template} = 'books/hw_form.tt2'; |
163 | } |
164 | |
165 | |
166 | =head2 hw_create_do |
167 | |
168 | Build an HTML::Widget form for book creation and updates |
169 | |
170 | =cut |
171 | |
172 | sub hw_create_do : Local { |
173 | my ($self, $c) = @_; |
174 | |
175 | # Retrieve the data from the form |
176 | my $title = $c->request->params->{title}; |
177 | my $rating = $c->request->params->{rating}; |
178 | my $authors = $c->request->params->{authors}; |
179 | |
180 | # Call create() on the book model object. Pass the table |
181 | # columns/field values we want to set as hash values |
182 | my $book = $c->model('MyAppDB::Book')->create({ |
183 | title => $title, |
184 | rating => $rating |
185 | }); |
186 | |
187 | # Add a record to the join table for this book, mapping to |
188 | # appropriate author |
189 | $book->add_to_book_authors({author_id => $authors}); |
190 | |
191 | # Set a status message for the user |
192 | $c->stash->{status_msg} = 'Book created'; |
193 | |
194 | # Use 'hw_create' to redisplay the form |
195 | $c->detach('hw_create'); |
196 | |
197 | } |
198 | |
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199 | Note how we use C<make_book_widget> to build the core parts of the form |
200 | in one location, but we set the action (the URL the form is sent to when |
201 | the user clicks the 'Submit' button) separately in C<hw_create>. Doing |
202 | so allows us to have the same form submit the data to different actions |
203 | (e.g., C<hw_create_do> for a create operation but C<hw_update_do> to |
204 | update an existing book object). |
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205 | |
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206 | =head2 Update the CSS |
207 | |
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208 | Edit C<root/src/ttsite.css> and add the following lines to the bottom of |
209 | the file: |
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210 | |
211 | label { |
212 | display: block; |
213 | width: 10em; |
214 | position: relative; |
215 | margin: .5em 0em; |
216 | } |
217 | label input { |
218 | position: absolute; |
219 | left: 100%; |
220 | } |
221 | label select { |
222 | position: absolute; |
223 | left: 100%; |
224 | } |
225 | .submit { |
226 | margin-top: 2em;; |
227 | } |
228 | .error_messages { |
229 | color: [% site.col.error %]; |
230 | } |
231 | |
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232 | These changes will display form elements vertically and also show error |
233 | messages in red. Note that we are pulling the color scheme settings |
234 | from the C<root/lib/config/col> file that was created by the TTSite |
235 | helper. This allows us to change the color used by various error styles |
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236 | in the CSS from a single location. |
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237 | |
238 | =head2 Create a Template Page To Display The Form |
239 | |
240 | C<root/src/books/hw_form.tt2> |
241 | [% META title = 'Create/Update Book' %] |
242 | |
243 | [% widget_result.as_xml %] |
244 | |
245 | <p><a href="[% Catalyst.uri_for('list') %]">Return to book list</a></p> |
246 | |
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247 | =head2 Add Links for Create and Update via C<HTML::Widget> |
248 | |
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249 | Open C<root/src/books/list.tt2> in your editor and add the following to |
250 | the bottom of the existing file: |
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251 | |
252 | <p> |
253 | HTML::Widget: |
254 | <a href="[% Catalyst.uri_for('hw_create') %]">Create</a> |
255 | <a href="[% Catalyst.uri_for('hw_update') %]">Update</a> |
256 | </p> |
257 | |
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258 | =head2 Test The <HTML::Widget> Create Form |
259 | |
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260 | Press C<Ctrl-C> to kill the previous server instance (if it's still |
261 | running) and restart it: |
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262 | |
263 | $ script/myapp_server.pl |
264 | |
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265 | Login as C<test01>. Once at the Book List page, click the HTML::Widget |
266 | "Create" link to display for form produced by C<make_book_widget>. Fill |
267 | out the form with the following values: Title = "Internetworking with |
268 | TCP/IP Vol. II", Rating = "4", and Author = "Comer". Click Submit, and |
269 | you will be returned to the Create/Update Book page with a "Book |
270 | created" status message displayed. Click "Return to book list" to view |
271 | the newly created book on the main list. |
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272 | |
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273 | Also note that this implementation allows you to can create books with |
274 | bogus information. Although we have constrained the authors with the |
275 | drop-down list, there are no restrictions on items such as the length of |
276 | the title (for example, you can create a one-letter title) and value for |
277 | the rating (you can use any number you want, and even non-numeric values |
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278 | with SQLite). The next section will address this concern. |
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279 | |
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280 | B<Note:> Depending on the database you are using and how you established |
281 | the columns in your tables, the database could obviously provide various |
282 | levels of "type enforcement" on your data. The key point being made in |
283 | the previous paragraph is that the I<web application> itself is not |
284 | performing any validation. |
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285 | |
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286 | =head1 C<HTML::WIDGET> VALIDATION AND FILTERING |
287 | |
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288 | Although the use of L<HTML::Widget|HTML::Widget> in the previous section |
289 | did provide an automated mechanism to build the form, the real power of |
290 | this module stems from functionality that can automatically validate and |
291 | filter the user input. Validation uses constraints to be sure that |
292 | users input appropriate data (for example, that the email field of a |
293 | form contains a valid email address). Filtering can be used to remove |
294 | extraneous whitespace from fields or to escape meta-characters in user |
295 | input. |
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296 | |
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297 | =head2 Add Constraints and Filters to the Widget Creation Method |
298 | |
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299 | Open C<lib/MyApp/Controller/Books.pm> in your editor and update the |
300 | C<make_book_widget> method to match the following (new sections have |
301 | been marked with a C<*** NEW:> comment): |
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302 | |
303 | sub make_book_widget { |
304 | my ($self, $c) = @_; |
305 | |
306 | # Create an HTML::Widget to build the form |
307 | my $w = $c->widget('book_form')->method('post'); |
308 | |
309 | # Get authors |
310 | my @authorObjs = $c->model("MyAppDB::Author")->all(); |
311 | my @authors = map {$_->id => $_->last_name } |
312 | sort {$a->last_name cmp $b->last_name} @authorObjs; |
313 | |
314 | # Create the form feilds |
315 | $w->element('Textfield', 'title' )->label('Title')->size(60); |
316 | $w->element('Textfield', 'rating' )->label('Rating')->size(1); |
317 | # ***NEW: Convert to multi-select list |
318 | $w->element('Select', 'authors')->label('Authors') |
319 | ->options(@authors)->multiple(1)->size(3); |
320 | $w->element('Submit', 'submit' )->value('submit'); |
321 | |
322 | # ***NEW: Set constraints |
323 | $w->constraint(All => qw/title rating authors/) |
324 | ->message('Required. '); |
325 | $w->constraint(Integer => qw/rating/) |
326 | ->message('Must be an integer. '); |
327 | $w->constraint(Range => qw/rating/)->min(1)->max(5) |
328 | ->message('Must be a number between 1 and 5. '); |
329 | $w->constraint(Length => qw/title/)->min(5)->max(50) |
330 | ->message('Must be between 5 and 50 characters. '); |
331 | |
332 | # ***NEW: Set filters |
333 | for my $column (qw/title rating authors/) { |
334 | $w->filter( HTMLEscape => $column ); |
335 | $w->filter( TrimEdges => $column ); |
336 | } |
337 | |
338 | # Return the widget |
339 | return $w; |
340 | } |
341 | |
342 | The main changes are: |
343 | |
344 | =over 4 |
345 | |
346 | =item * |
347 | |
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348 | The C<Select> element for C<authors> is changed from a single-select |
349 | drop-down to a multi-select list by adding calls to C<multiple> (set to |
350 | C<true>) and C<size> (set to the number of rows to display). |
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351 | |
352 | =item * |
353 | |
354 | Four sets of constraints are added to provide validation of the user input. |
355 | |
356 | =item * |
357 | |
358 | Two filters are run on every field to remove and escape unwanted input. |
359 | |
360 | =back |
361 | |
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362 | =head2 Rebuild the Form Submission Method to Include Validation |
363 | |
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364 | Edit C<lib/MyApp/Controller/Books.pm> and change C<hw_create_do> to |
365 | match the following code (enough of the code is different that you |
366 | probably want to cut and paste this over code the existing method): |
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367 | |
368 | sub hw_create_do : Local { |
369 | my ($self, $c) = @_; |
370 | |
371 | # Retrieve the data from the form |
372 | my $title = $c->request->params->{title}; |
373 | my $rating = $c->request->params->{rating}; |
374 | my $authors = $c->request->params->{authors}; |
375 | |
376 | # Create the widget and set the action for the form |
377 | my $w = $self->make_book_widget($c); |
378 | $w->action($c->uri_for('hw_create_do')); |
379 | |
380 | # Validate the form parameters |
381 | my $result = $w->process($c->req); |
382 | |
383 | # Write form (including validation error messages) to |
384 | # stash variable for use in template |
385 | $c->stash->{widget_result} = $result; |
386 | |
387 | # Were their validation errors? |
388 | if ($result->has_errors) { |
389 | # Warn the user at the top of the form that there were errors. |
390 | # Note that there will also be per-field feedback on |
391 | # validation errors because of '$w->process($c->req)' above. |
392 | $c->stash->{error_msg} = 'Validation errors!'; |
393 | } else { |
394 | # Everything validated OK, so do the create |
395 | # Call create() on the book model object. Pass the table |
396 | # columns/field values we want to set as hash values |
397 | my $book = $c->model('MyAppDB::Book')->create({ |
398 | title => $title, |
399 | rating => $rating |
400 | }); |
401 | |
402 | # Add a record to the join table for this book, mapping to |
403 | # appropriate author. Note that $authors will be 1 author as |
404 | # a scalar or ref to list of authors depending on how many the |
405 | # user selected; the 'ref $authors ?...' handles both cases |
406 | foreach my $author (ref $authors ? @$authors : $authors) { |
407 | $book->add_to_book_authors({author_id => $author}); |
408 | } |
409 | # Set a status message for the user |
410 | $c->stash->{status_msg} = 'Book created'; |
411 | } |
412 | |
413 | # Set the template |
414 | $c->stash->{template} = 'books/hw_form.tt2'; |
415 | } |
416 | |
417 | The key changes to C<hw_create_do> are: |
418 | |
419 | =over 4 |
420 | |
421 | =item * |
422 | |
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423 | C<hw_create_do> no longer does a C<detach> to C<hw_create> to redisplay |
424 | the form. Now that C<hw_create_do> has to process the form in order to |
425 | perform the validation, we go ahead and build a complete set of form |
426 | presentation logic into C<hw_create_do> (for example, C<hw_create_do> |
427 | now has a C<$c-E<gt>stash-E<gt>{template}> line). Note that if we |
428 | process the form in C<hw_create_do> I<and> forward/detach back to |
429 | <hw_create>, we would end up with C<make_book_widget> being called |
430 | twice, resulting in a duplicate set of elements being added to the form. |
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431 | |
432 | =item * |
433 | |
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434 | C<$w-E<gt>process($c-E<gt>req)> is called to run the validation logic. |
435 | Not only does this set the C<has_errors> flag if validation errors are |
436 | encountered, it returns a string containing any field-specific warning |
437 | messages. |
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438 | |
439 | =item * |
440 | |
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441 | An C<if> statement checks if any validation errors were encountered. If |
442 | so, C<$c-E<gt>stash-E<gt>{error_msg}> is set and the input form is |
443 | redisplayed. If no errors were found, the object is created in a manner |
444 | similar to the prior version of the C<hw_create_do> method. |
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445 | |
446 | =back |
447 | |
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448 | =head2 Try Out the Form |
449 | |
450 | Press C<Ctrl-C> to kill the previous server instance (if it's still running) and restart it: |
451 | |
452 | $ script/myapp_server.pl |
453 | |
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454 | Now try adding a book with various errors: title less than 5 characters, |
455 | non-numeric rating, a rating of 0 or 6, etc. Also try selecting one, |
456 | two, and zero authors. When you click Submit, the HTML::Widget |
457 | C<constraint> items will validate the logic and insert feedback as |
458 | appropriate. |
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459 | |
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460 | =head1 Enable C<DBIx::Class::HTMLWidget> Support |
461 | |
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462 | In this section we will take advantage of some of the "auto-population" |
463 | features of C<DBIx::Class::HTMLWidget>. Enabling |
464 | C<DBIx::Class::HTMLWidget> provides two additional methods to your DBIC |
465 | model classes: |
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466 | |
467 | =over 4 |
468 | |
469 | =item * |
470 | |
471 | fill_wiget() |
472 | |
473 | Takes data from the database and transfers it to your form widget. |
474 | |
475 | =item * |
476 | |
477 | populate_from_widget() |
478 | |
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479 | Takes data from a form widget and uses it to update the corresponding |
480 | records in the database. |
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481 | |
482 | =back |
483 | |
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484 | In other words, the two methods are a mirror image of each other: one |
485 | reads from the database while the other writes to the database. |
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486 | |
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487 | =head2 Add C<DBIx::Class::HTMLWidget> to DBIC Model |
488 | |
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489 | In order to use L<DBIx::Class::HTMLWidget|DBIx::Class::HTMLWidget>, we |
490 | need to add C<HTMLWidget> to the C<load_components> line of DBIC result |
491 | source files that need to use the C<fill_widget> and |
492 | C<populate_from_widget> methods. In this case, open |
493 | C<lib/MyAppDB/Book.pm> and update the C<load_components> line to match: |
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494 | |
495 | __PACKAGE__->load_components(qw/PK::Auto Core HTMLWidget/); |
496 | |
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497 | =head2 Use C<populate_from_widget> in C<hw_create_do> |
498 | |
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499 | Edit C<lib/MyApp/Controller/Books.pm> and update C<hw_create_do> to |
500 | match the following code: |
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501 | |
502 | =head2 hw_create_do |
503 | |
504 | Build an HTML::Widget form for book creation and updates |
505 | |
506 | =cut |
507 | |
508 | sub hw_create_do : Local { |
509 | my ($self, $c) = @_; |
510 | |
511 | # Create the widget and set the action for the form |
512 | my $w = $self->make_book_widget($c); |
513 | $w->action($c->uri_for('hw_create_do')); |
514 | |
515 | # Validate the form parameters |
516 | my $result = $w->process($c->req); |
517 | |
518 | # Write form (including validation error messages) to |
519 | # stash variable for use in template |
520 | $c->stash->{widget_result} = $result; |
521 | |
522 | # Were their validation errors? |
523 | if ($result->has_errors) { |
524 | # Warn the user at the top of the form that there were errors. |
525 | # Note that there will also be per-field feedback on |
526 | # validation errors because of '$w->process($c->req)' above. |
527 | $c->stash->{error_msg} = 'Validation errors!'; |
528 | } else { |
529 | my $book = $c->model('MyAppDB::Book')->new({}); |
530 | $book->populate_from_widget($result); |
531 | |
532 | # Add a record to the join table for this book, mapping to |
533 | # appropriate author. Note that $authors will be 1 author as |
534 | # a scalar or ref to list of authors depending on how many the |
535 | # user selected; the 'ref $authors ?...' handles both cases |
536 | my $authors = $c->request->params->{authors}; |
537 | foreach my $author (ref $authors ? @$authors : $authors) { |
538 | $book->add_to_book_authors({author_id => $author}); |
539 | } |
540 | |
541 | # Set a status message for the user |
542 | $c->stash->{status_msg} = 'Book created'; |
543 | } |
544 | |
545 | # Set the template |
546 | $c->stash->{template} = 'books/hw_form.tt2'; |
547 | } |
548 | |
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549 | In this version of C<hw_create_do> we removed the logic that manually |
550 | pulled the form variables and used them to call |
551 | C<$c-E<gt>model('MyAppDB::Book')-E<gt>create> and replaced it with a |
552 | single call to C<$book-E<gt>populate_from_widget>. Note that we still |
553 | have to call C<$book-E<gt>add_to_book_authors> once per author because |
554 | C<populate_from_widget> does not currently handle the relationships |
555 | between tables. |
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556 | |
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557 | =head1 AUTHOR |
558 | |
559 | Kennedy Clark, C<hkclark@gmail.com> |
560 | |
561 | Please report any errors, issues or suggestions to the author. |
562 | |
563 | Copyright 2006, Kennedy Clark. All rights reserved. |
564 | |
3c098c71 |
565 | This library is free software; you can redistribute it and/or modify it |
566 | under the same terms as Perl itself. |
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567 | |
568 | Version: .94 |
569 | |