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1 | =head1 NAME |
2 | |
3 | Catalyst::Manual::Tutorial::MoreCatalystBasics - Catalyst Tutorial - Part 3: More Catalyst Application Development Basics |
4 | |
5 | |
6 | =head1 OVERVIEW |
7 | |
8 | This is B<Part 3 of 10> for the Catalyst tutorial. |
9 | |
10 | L<Tutorial Overview|Catalyst::Manual::Tutorial> |
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<More Catalyst Basics> |
25 | |
26 | =item 4 |
27 | |
28 | L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD> |
29 | |
30 | =item 5 |
31 | |
32 | L<Authentication|Catalyst::Manual::Tutorial::Authentication> |
33 | |
34 | =item 6 |
35 | |
36 | L<Authorization|Catalyst::Manual::Tutorial::Authorization> |
37 | |
38 | =item 7 |
39 | |
40 | L<Debugging|Catalyst::Manual::Tutorial::Debugging> |
41 | |
42 | =item 8 |
43 | |
44 | L<Testing|Catalyst::Manual::Tutorial::Testing> |
45 | |
46 | =item 9 |
47 | |
48 | L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD> |
49 | |
50 | =item 10 |
51 | |
52 | L<Appendices|Catalyst::Manual::Tutorial::Appendices> |
53 | |
54 | =back |
55 | |
56 | |
57 | =head1 DESCRIPTION |
58 | |
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59 | This part of the tutorial builds on the work done in Part 2 to explore |
60 | some features that are more typical of "real world" web applications. |
61 | From this part of the tutorial onward, we will be building a simple |
62 | book database application. Although the application will be too |
63 | limited to be of use to anyone, it should provide a basic environment |
64 | where we can explore a variety of features used in virtually all web |
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65 | applications. |
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::Intro|Catalyst::Manual::Tutorial::Intro>. |
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70 | |
71 | |
72 | =head1 CREATE A NEW APPLICATION |
73 | |
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74 | The remainder of the tutorial will build an application called C<MyApp>. |
75 | First use the Catalyst C<catalyst.pl> script to initialize the framework |
76 | for the C<MyApp> application (make sure you aren't still inside the |
77 | directory of the C<Hello> application from the previous part of the |
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78 | tutorial): |
79 | |
80 | $ catalyst.pl MyApp |
81 | created "MyApp" |
82 | created "MyApp/script" |
83 | created "MyApp/lib" |
84 | created "MyApp/root" |
85 | ... |
86 | created "MyApp/script/myapp_create.pl" |
87 | $ cd MyApp |
88 | |
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89 | This creates a similar skeletal structure to what we saw in Part 2 of |
90 | the tutorial, except with C<MyApp> and C<myapp> substituted for |
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91 | C<Hello> and C<hello>. |
92 | |
93 | |
94 | =head1 EDIT THE LIST OF CATALYST PLUGINS |
95 | |
96 | One of the greatest benefits of Catalyst is that it has such a large |
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97 | library of plugins and base classes available. Plugins are used to |
98 | seamlessly integrate existing Perl modules into the overall Catalyst |
99 | framework. In general, they do this by adding additional methods to the |
100 | C<context> object (generally written as C<$c>) that Catalyst passes to |
101 | every component throughout the framework. |
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102 | |
103 | By default, Catalyst enables three plugins/flags: |
104 | |
105 | =over 4 |
106 | |
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107 | =item * |
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108 | |
109 | C<-Debug> Flag |
110 | |
111 | Enables the Catalyst debug output you saw when we started the |
112 | C<script/myapp_server.pl> development server earlier. You can remove |
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113 | this item when you place your application into production. |
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114 | |
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115 | As you may have noticed, C<-Debug> is not a plugin, but a I<flag>. |
116 | Although most of the items specified on the C<__PACKAGE__-E<gt>setup> |
117 | line of your application class will be plugins, Catalyst supports a |
118 | limited number of flag options (of these, C<-Debug> is the most |
119 | common). See the documentation for C<Catalyst.pm> to get details on |
120 | other flags (currently C<-Engine>, C<-Home>, and C<-Log>). |
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121 | |
122 | If you prefer, you can use the C<$c-E<gt>debug> method to enable debug |
123 | messages. |
124 | |
125 | B<TIP>: Depending on your needs, it can be helpful to permanently |
126 | remove C<-Debug> from C<lib/MyApp.pm> and then use the C<-d> option |
127 | to C<script/myapp_server.pl> to re-enable it just for the development |
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128 | server. We will not be using that approach in the tutorial, but feel |
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129 | free to make use of it in your own projects. |
130 | |
131 | =item * |
132 | |
133 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> |
134 | |
135 | C<ConfigLoader> provides an automatic way to load configurable |
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136 | parameters for your application from a central |
137 | L<Config::General|Config::General> file (versus having the values |
138 | hard-coded inside your Perl modules). Config::General uses syntax |
139 | very similar to Apache configuration files. We will see how to use |
140 | this feature of Catalyst during the authentication and authorization |
141 | sections (Part 5 and Part 6). |
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142 | |
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143 | B<IMPORTANT NOTE:> If you are using a version of |
144 | L<Catalyst::Devel|Catalyst::Devel> prior to version 1.06, you need to |
145 | be aware that Catalyst changed from a default format of YAML to the |
146 | more straightforward C<Config::General> format. This tutorial use the |
147 | newer C<myapp.conf> configuration file for C<Config::General> instead |
148 | of C<myapp.yml> for YAML. However, Catalyst has long supported both |
149 | formats and Catalyst will automatically use either C<myapp.conf> or |
150 | C<myapp.yml> (or any other format supported by |
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151 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> and |
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152 | L<Config::Any|Config::Any>). If you are using a versions of |
153 | Catalyst::Devel prior to 1.06, you can convert to the newer format by |
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154 | simply creating the C<myapp.conf> file manually and deleting |
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155 | C<myapp.yml>. The default contents of C<myapp.conf> should only |
156 | consist of one line: C<name MyApp>. |
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157 | |
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158 | B<TIP>: This script can be useful for converting between configuration |
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159 | formats: |
160 | |
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161 | perl -Ilib -e 'use MyApp; use Config::General; |
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162 | Config::General->new->save_file("myapp.conf", MyApp->config);' |
163 | |
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164 | B<NOTE:> The default C<myapp.conf> should look like: |
165 | |
166 | name MyApp |
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167 | |
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168 | =item * |
169 | |
170 | L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple> |
171 | |
172 | C<Static::Simple> provides an easy method of serving static content such |
173 | as images and CSS files under the development server. |
174 | |
175 | =back |
176 | |
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177 | For our application, we want to add one new plugin into the mix. To |
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178 | do this, edit C<lib/MyApp.pm> (this file is generally referred to as |
179 | your I<application class>) and delete the line with: |
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180 | |
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181 | __PACKAGE__->setup(qw/-Debug ConfigLoader Static::Simple/); |
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182 | |
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183 | Then replace it with: |
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184 | |
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185 | __PACKAGE__->setup(qw/ |
186 | -Debug |
187 | ConfigLoader |
188 | Static::Simple |
189 | |
190 | StackTrace |
191 | /); |
192 | |
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193 | B<Note:> Recent versions of C<Catalyst::Devel> have used a variety of |
194 | techniques to load these plugins/flags. If you are following along in |
195 | Ubuntu 8.10, you should have C<Catalyst::Devel> v1.07 and see the |
196 | default code shown above. If you are using v1.08, you should see the |
197 | following by default: |
198 | |
199 | use Catalyst qw/-Debug |
200 | ConfigLoader |
201 | Static::Simple/; |
202 | ... |
203 | __PACKAGE__->setup(); |
204 | |
205 | Don't let these variations confuse you -- they all accomplish the same |
206 | result. |
207 | |
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208 | This tells Catalyst to start using one new plugin, |
209 | L<Catalyst::Plugin::StackTrace|Catalyst::Plugin::StackTrace>, to add a |
210 | stack trace to the standard Catalyst "debug screen" (the screen |
211 | Catalyst sends to your browser when an error occurs). Be aware that |
212 | L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your |
213 | browser, not in the console window from which you're running your |
214 | application, which is where logging output usually goes. |
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215 | |
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216 | B<Notes:> |
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217 | |
218 | =over 4 |
219 | |
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220 | =item * |
221 | |
222 | C<__PACKAGE__> is just a shorthand way of referencing the name of the |
223 | package where it is used. Therefore, in C<MyApp.pm>, C<__PACKAGE__> |
224 | is equivalent to C<MyApp>. |
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225 | |
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226 | =item * |
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227 | |
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228 | You will want to disable L<StackTrace|Catalyst::Plugin::StackTrace> |
229 | before you put your application into production, but it can be helpful |
230 | during development. |
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231 | |
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232 | =item * |
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233 | |
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234 | When specifying plugins on the C<__PACKAGE__-E<gt>setup> line, you can |
235 | omit C<Catalyst::Plugin::> from the name. Additionally, you can |
236 | spread the plugin names across multiple lines as shown here, or place |
237 | them all on one (or more) lines as with the default configuration. |
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238 | |
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239 | =back |
240 | |
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241 | |
242 | =head1 CREATE A CATALYST CONTROLLER |
243 | |
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244 | As discussed earlier, controllers are where you write methods that |
245 | interact with user input. Typically, controller methods respond to |
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246 | C<GET> and C<POST> messages from the user's web browser. |
247 | |
248 | Use the Catalyst C<create> script to add a controller for book-related |
249 | actions: |
250 | |
251 | $ script/myapp_create.pl controller Books |
252 | exists "/home/me/MyApp/script/../lib/MyApp/Controller" |
253 | exists "/home/me/MyApp/script/../t" |
254 | created "/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm" |
255 | created "/home/me/MyApp/script/../t/controller_Books.t" |
256 | |
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257 | Then edit C<lib/MyApp/Controller/Books.pm> (as discussed in Part 2 of |
258 | the Tutorial, Catalyst has a separate directory under C<lib/MyApp> for |
259 | each of the three parts of MVC: C<Model>, C<View>, and C<Controller>) |
260 | and add the following method to the controller: |
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261 | |
262 | =head2 list |
263 | |
264 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
265 | |
266 | =cut |
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267 | |
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268 | sub list : Local { |
269 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
270 | # 'Context' that's used to 'glue together' the various components |
271 | # that make up the application |
272 | my ($self, $c) = @_; |
273 | |
274 | # Retrieve all of the book records as book model objects and store in the |
275 | # stash where they can be accessed by the TT template |
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276 | # $c->stash->{books} = [$c->model('DB::Books')->all]; |
277 | # But, for now, use this code until we create the model later |
278 | $c->stash->{books} = ''; |
279 | |
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280 | # Set the TT template to use. You will almost always want to do this |
281 | # in your action methods (action methods respond to user input in |
282 | # your controllers). |
283 | $c->stash->{template} = 'books/list.tt2'; |
284 | } |
285 | |
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286 | B<TIP>: See Appendix 1 for tips on removing the leading spaces when |
287 | cutting and pasting example code from POD-based documents. |
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288 | |
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289 | Programmers experienced with object-oriented Perl should recognize |
290 | C<$self> as a reference to the object where this method was called. |
291 | On the other hand, C<$c> will be new to many Perl programmers who have |
292 | not used Catalyst before (it's sometimes written as C<$context>). The |
293 | Context object is automatically passed to all Catalyst components. It |
294 | is used to pass information between components and provide access to |
295 | Catalyst and plugin functionality. |
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296 | |
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297 | Catalyst actions are regular Perl methods, but they make use of |
298 | attributes (the "C<: Local>" next to the "C<sub list>" in the code |
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299 | above) to provide additional information to the Catalyst dispatcher |
300 | logic (note that the space between the colon and the attribute name is |
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301 | optional... you will see attributes written both ways). Most Catalyst |
302 | Controllers use one of five action types: |
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303 | |
304 | =over 4 |
305 | |
306 | =item * |
307 | |
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308 | B<:Private> -- Use C<:Private> for methods that you want to make into |
309 | an action, but you do not want Catalyst to directly expose the action |
310 | to your users. Catalyst will not map C<:Private> methods to a URI. |
311 | Use them for various sorts of "special" methods (the C<begin>, |
312 | C<auto>, etc. discussed below) or for methods you want to be able to |
313 | C<forward> or C<detach> to. (If the method is a plain old "helper |
314 | method" that you don't want to be an action at all, then just define |
315 | the method without any attribute -- you can call it in your code, but |
316 | the Catalyst dispatcher will ignore it.) |
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317 | |
318 | =over 4 |
319 | |
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320 | There are five types of "special" build-in C<:Private> actions: |
321 | C<begin>, C<end>, C<default>, C<index>, and C<auto>. |
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322 | |
323 | =item * |
324 | |
325 | With C<begin>, C<end>, C<default>, C<index> private actions, only the |
326 | most specific action of each type will be called. For example, if you |
327 | define a C<begin> action in your controller it will I<override> a |
328 | C<begin> action in your application/root controller -- I<only> the |
329 | action in your controller will be called. |
330 | |
331 | =item * |
332 | |
333 | Unlike the other actions where only a single method is called for each |
334 | request, I<every> auto action along the chain of namespaces will be |
335 | called. Each C<auto> action will be called I<from the application/root |
336 | controller down through the most specific class>. |
337 | |
338 | =back |
339 | |
340 | =item * |
341 | |
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342 | B<:Path> -- C<:Path> actions let you map a method to an explicit URI |
343 | path. For example, "C<:Path('list')>" in |
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344 | C<lib/MyApp/Controller/Books.pm> would match on the URL |
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345 | C<http://localhost:3000/books/list> but "C<:Path('/list')>" would match |
346 | on C<http://localhost:3000/list>. You can use C<:Args()> to specify |
347 | how many arguments an action should except. See |
348 | L<Catalyst::Manual::Intro/Action_types> for more information and a few |
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349 | examples. |
350 | |
351 | =item * |
352 | |
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353 | B<:Local> -- C<:Local> is merely a shorthand for |
354 | "C<:Path('_name_of_method_')>". For example, these are equivalent: |
355 | "C<sub create_book :Local {...}>" and |
356 | "C<sub create_book :Path('create_book') {...}>". |
357 | |
358 | =item * |
359 | |
360 | B<:Global> -- C<:Global> is merely a shorthand for |
361 | "C<:Path('/_name_of_method_')>". For example, these are equivalent: |
362 | "C<sub create_book :Global {...}>" and |
363 | "C<sub create_book :Path('/create_book') {...}>". |
364 | |
365 | =item * |
366 | |
367 | B<:Chained> -- Newer Catalyst applications tend to use the Chained |
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368 | dispatch form of action types because of its power and flexibility. |
369 | It allows a series of controller methods to automatically be dispatched |
370 | to service a single user request. See |
371 | L<Catalyst::Manual::Tutorial::BasicCRUD|Catalyst::Manual::Tutorial::BasicCRUD> |
372 | and L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained> |
373 | for more information on chained actions. |
374 | |
375 | =back |
376 | |
377 | You should refer to L<Catalyst::Manual::Intro/Action_types> for |
378 | additional information and for coverage of some lesser-used action |
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379 | types not discussed here (C<Regex> and C<LocalRegex>). |
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380 | |
381 | |
382 | =head1 CATALYST VIEWS |
383 | |
384 | As mentioned in Part 2 of the tutorial, views are where you render |
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385 | output, typically for display in the user's web browser (but also |
386 | possibly using other display output-generation systems). The code in |
387 | C<lib/MyApp/View> selects the I<type> of view to use, with the actual |
388 | rendering template found in the C<root> directory. As with virtually |
389 | every aspect of Catalyst, options abound when it comes to the specific |
390 | view technology you adopt inside your application. However, most |
391 | Catalyst applications use the Template Toolkit, known as TT (for more |
392 | information on TT, see L<http://www.template-toolkit.org>). Other |
393 | somewhat popular view technologies include Mason |
394 | (L<http://www.masonhq.com> and L<http://www.masonbook.com>) and |
395 | L<HTML::Template> (L<http://html-template.sourceforge.net>). |
396 | |
397 | |
398 | =head2 Create a Catalyst View |
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399 | |
400 | When using TT for the Catalyst view, there are two main helper scripts: |
401 | |
402 | =over 4 |
403 | |
404 | =item * |
405 | |
406 | L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT> |
407 | |
408 | =item * |
409 | |
410 | L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite> |
411 | |
412 | =back |
413 | |
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414 | Both helpers are similar. C<TT> creates the C<lib/MyApp/View/TT.pm> |
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415 | file and leaves the creation of any hierarchical template organization |
416 | entirely up to you. (It also creates a C<t/view_TT.t> file for testing; |
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417 | test cases will be discussed in Part 8.) C<TTSite>, on the other hand, |
418 | creates a modular and hierarchical view layout with |
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419 | separate Template Toolkit (TT) files for common header and footer |
420 | information, configuration values, a CSS stylesheet, and more. |
421 | |
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422 | While C<TTSite> was useful to bootstrap a project, its use is now |
423 | deprecated and to be considered historical. For most Catalyst |
424 | applications it adds redundant functionality and structure; many in the |
425 | Catalyst community recommend that it's easier to learn both Catalyst and |
426 | Template Toolkit if you use the more basic C<TT> approach. |
427 | Consequently, this tutorial will use "plain old TT." |
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428 | |
429 | Enter the following command to enable the C<TT> style of view |
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430 | rendering for this tutorial: |
431 | |
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432 | $ script/myapp_create.pl view TT TT |
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433 | exists "/home/me/MyApp/script/../lib/MyApp/View" |
434 | exists "/home/me/MyApp/script/../t" |
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435 | created "/home/me/MyApp/script/../lib/MyApp/View/TT.pm" |
436 | created "/home/me/MyApp/script/../t/view_TT.t" |
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437 | |
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438 | This simply creates a view called C<TT> (the second 'TT' argument) in |
439 | a file called C<TT.pm> (the first 'TT' argument). It is now up to you |
440 | to decide how you want to structure your view layout. For the |
441 | tutorial, we will start with a very simple TT template to initially |
442 | demonstrate the concepts, but quickly migrate to a more typical |
443 | "wrapper page" type of configuration (where the "wrapper" controls the |
444 | overall "look and feel" of your site from a single file or set of |
445 | files). |
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446 | |
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447 | Edit C<lib/MyApp/View/TT.pm> and you should see that the default |
448 | contents contains something similar to the following: |
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449 | |
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450 | __PACKAGE__->config(TEMPLATE_EXTENSION => '.tt'); |
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451 | |
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452 | And update it to match: |
453 | |
454 | __PACKAGE__->config( |
455 | # Change default TT extension |
456 | TEMPLATE_EXTENSION => '.tt2', |
457 | # Set the location for TT files |
458 | INCLUDE_PATH => [ |
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459 | MyApp->path_to( 'root', 'src' ), |
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460 | ], |
461 | ); |
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462 | |
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463 | B<NOTE:> Make sure to add a comma after '.tt2' outside the single |
464 | quote. |
465 | |
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466 | This changes the default extension for Template Toolkit from '.tt' to |
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467 | '.tt2' and changes the base directory for your template files from |
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468 | C<root> to C<root/src>. These changes from the default are done mostly |
469 | to facilitate the application we're developing in this tutorial; as with |
470 | most things Perl, there's more than one way to do it... |
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471 | |
472 | |
473 | =head2 Create a TT Template Page |
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474 | |
475 | First create a directory for book-related TT templates: |
476 | |
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477 | $ mkdir -p root/src/books |
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478 | |
479 | Then create C<root/src/books/list.tt2> in your editor and enter: |
480 | |
481 | [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%] |
482 | [% # see this "chomping" in your browser because HTML ignores blank lines, but -%] |
483 | [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%] |
484 | [%- # optional, but both the beginning and the ending TT tags support chomping. -%] |
485 | |
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486 | [% # Provide a title -%] |
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487 | [% META title = 'Book List' -%] |
488 | |
489 | <table> |
490 | <tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr> |
491 | [% # Display each book in a table row %] |
492 | [% FOREACH book IN books -%] |
493 | <tr> |
494 | <td>[% book.title %]</td> |
495 | <td>[% book.rating %]</td> |
496 | </tr> |
497 | [% END -%] |
498 | </table> |
499 | |
500 | As indicated by the inline comments above, the C<META title> line uses |
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501 | TT's META feature to provide a title to the "wrapper" that we will |
502 | create later. Meanwhile, the C<FOREACH> loop iterates through each |
503 | C<book> model object and prints the C<title> and C<rating> fields. |
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504 | |
505 | If you are new to TT, the C<[%> and C<%]> tags are used to delimit TT |
506 | code. TT supports a wide variety of directives for "calling" other |
507 | files, looping, conditional logic, etc. In general, TT simplifies the |
508 | usual range of Perl operators down to the single dot (C<.>) operator. |
509 | This applies to operations as diverse as method calls, hash lookups, and |
510 | list index values (see |
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511 | L<http://search.cpan.org/perldoc?Template::Manual::Variables> |
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512 | for details and examples). In addition to the usual C<Template> module |
513 | Pod documentation, you can access the TT manual at |
55beb65d |
514 | L<http://search.cpan.org/perldoc?Template::Manual>. |
3533daff |
515 | |
1390ef0e |
516 | B<TIP:> While you can build all sorts of complex logic into your TT |
517 | templates, you should in general keep the "code" part of your templates |
518 | as simple as possible. If you need more complex logic, create helper |
519 | methods in your model that abstract out a set of code into a single call |
520 | from your TT template. (Note that the same is true of your controller |
521 | logic as well -- complex sections of code in your controllers should |
522 | often be pulled out and placed into your model objects.) |
523 | |
524 | |
525 | =head2 Test Run The Application |
526 | |
527 | To test your work so far, first start the development server: |
528 | |
529 | $ script/myapp_server.pl |
530 | |
531 | Then point your browser to L<http://localhost:3000> and you should |
532 | still get the Catalyst welcome page. Next, change the URL in your |
533 | browser to L<http://localhost:3000/books/list>. If you have |
534 | everything working so far, you should see a web page that displays |
535 | nothing other than our column headers for "Title", "Rating", and |
536 | "Author(s)" -- we will not see any books until we get the database and |
537 | model working below. |
538 | |
539 | If you run into problems getting your application to run correctly, it |
540 | might be helpful to refer to some of the debugging techniques covered in |
541 | the L<Debugging|Catalyst::Manual::Tutorial::Debugging> part of the |
542 | tutorial. |
3533daff |
543 | |
544 | |
545 | =head1 CREATE A SQLITE DATABASE |
546 | |
547 | In this step, we make a text file with the required SQL commands to |
1390ef0e |
548 | create a database table and load some sample data. We will use SQLite, |
549 | a popular database that is lightweight and easy to use. Open |
550 | C<myapp01.sql> in your editor and enter: |
3533daff |
551 | |
552 | -- |
553 | -- Create a very simple database to hold book and author information |
554 | -- |
555 | CREATE TABLE books ( |
556 | id INTEGER PRIMARY KEY, |
557 | title TEXT , |
558 | rating INTEGER |
559 | ); |
560 | -- 'book_authors' is a many-to-many join table between books & authors |
561 | CREATE TABLE book_authors ( |
562 | book_id INTEGER, |
563 | author_id INTEGER, |
564 | PRIMARY KEY (book_id, author_id) |
565 | ); |
566 | CREATE TABLE authors ( |
567 | id INTEGER PRIMARY KEY, |
568 | first_name TEXT, |
569 | last_name TEXT |
570 | ); |
571 | --- |
572 | --- Load some sample data |
573 | --- |
574 | INSERT INTO books VALUES (1, 'CCSP SNRS Exam Certification Guide', 5); |
575 | INSERT INTO books VALUES (2, 'TCP/IP Illustrated, Volume 1', 5); |
576 | INSERT INTO books VALUES (3, 'Internetworking with TCP/IP Vol.1', 4); |
577 | INSERT INTO books VALUES (4, 'Perl Cookbook', 5); |
578 | INSERT INTO books VALUES (5, 'Designing with Web Standards', 5); |
579 | INSERT INTO authors VALUES (1, 'Greg', 'Bastien'); |
580 | INSERT INTO authors VALUES (2, 'Sara', 'Nasseh'); |
581 | INSERT INTO authors VALUES (3, 'Christian', 'Degu'); |
582 | INSERT INTO authors VALUES (4, 'Richard', 'Stevens'); |
583 | INSERT INTO authors VALUES (5, 'Douglas', 'Comer'); |
584 | INSERT INTO authors VALUES (6, 'Tom', 'Christiansen'); |
585 | INSERT INTO authors VALUES (7, 'Nathan', 'Torkington'); |
586 | INSERT INTO authors VALUES (8, 'Jeffrey', 'Zeldman'); |
587 | INSERT INTO book_authors VALUES (1, 1); |
588 | INSERT INTO book_authors VALUES (1, 2); |
589 | INSERT INTO book_authors VALUES (1, 3); |
590 | INSERT INTO book_authors VALUES (2, 4); |
591 | INSERT INTO book_authors VALUES (3, 5); |
592 | INSERT INTO book_authors VALUES (4, 6); |
593 | INSERT INTO book_authors VALUES (4, 7); |
594 | INSERT INTO book_authors VALUES (5, 8); |
595 | |
3533daff |
596 | Then use the following command to build a C<myapp.db> SQLite database: |
597 | |
598 | $ sqlite3 myapp.db < myapp01.sql |
599 | |
600 | If you need to create the database more than once, you probably want to |
601 | issue the C<rm myapp.db> command to delete the database before you use |
1390ef0e |
602 | the C<sqlite3 myapp.db E<lt> myapp01.sql> command. |
3533daff |
603 | |
604 | Once the C<myapp.db> database file has been created and initialized, you |
605 | can use the SQLite command line environment to do a quick dump of the |
606 | database contents: |
607 | |
608 | $ sqlite3 myapp.db |
609 | SQLite version 3.4.2 |
610 | Enter ".help" for instructions |
611 | sqlite> select * from books; |
612 | 1|CCSP SNRS Exam Certification Guide|5 |
613 | 2|TCP/IP Illustrated, Volume 1|5 |
614 | 3|Internetworking with TCP/IP Vol.1|4 |
615 | 4|Perl Cookbook|5 |
616 | 5|Designing with Web Standards|5 |
617 | sqlite> .q |
618 | $ |
619 | |
620 | Or: |
621 | |
622 | $ sqlite3 myapp.db "select * from books" |
623 | 1|CCSP SNRS Exam Certification Guide|5 |
624 | 2|TCP/IP Illustrated, Volume 1|5 |
625 | 3|Internetworking with TCP/IP Vol.1|4 |
626 | 4|Perl Cookbook|5 |
627 | 5|Designing with Web Standards|5 |
628 | |
629 | As with most other SQL tools, if you are using the full "interactive" |
630 | environment you need to terminate your SQL commands with a ";" (it's not |
631 | required if you do a single SQL statement on the command line). Use |
632 | ".q" to exit from SQLite from the SQLite interactive mode and return to |
633 | your OS command prompt. |
634 | |
a6d800ac |
635 | For using other databases, such as PostgreSQL or MySQL, see |
636 | L<Appendix 2|Catalyst::Manual::Tutorial::Appendices>. |
3533daff |
637 | |
638 | =head1 DATABASE ACCESS WITH C<DBIx::Class> |
639 | |
191dee29 |
640 | Catalyst can be used with virtually any form of persistent datastore |
641 | available via Perl. For example, |
642 | L<Catalyst::Model::DBI|Catalyst::Model::DBI> can be used to easily |
643 | access databases through the traditional Perl C<DBI> interface. However, |
644 | most Catalyst applications use some form of ORM technology to |
645 | automatically create and save model objects as they are used. Although |
646 | L<Class::DBI|Class::DBI> has been a popular choice in the past, Matt |
647 | Trout's L<DBIx::Class|DBIx::Class> (abbreviated as "DBIC") has rapidly |
648 | emerged as the Perl-based ORM technology of choice. Most new Catalyst |
649 | applications rely on DBIC, as will this tutorial. |
3533daff |
650 | |
3533daff |
651 | |
1390ef0e |
652 | =head2 Create a Dynamic DBIC Model |
653 | |
654 | Use the C<create=dynamic> model helper option to build a model that |
3533daff |
655 | dynamically reads your database structure every time the application |
656 | starts: |
657 | |
d0496197 |
658 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema create=dynamic dbi:SQLite:myapp.db |
1390ef0e |
659 | exists "/home/me/MyApp/script/../lib/MyApp/Model" |
660 | exists "/home/me/MyApp/script/../t" |
661 | exists "/home/me/MyApp/script/../lib/MyApp" |
662 | created "/home/me/MyApp/script/../lib/MyApp/Schema.pm" |
663 | created "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm" |
664 | created "/home/me/MyApp/script/../t/model_DB.t" |
3533daff |
665 | |
666 | |
d0496197 |
667 | C<DB> is the name of the model class to be created by the helper in |
1390ef0e |
668 | C<lib/MyApp/Model>. C<DBIC::Schema> is the type of the model to |
669 | create. C<MyApp::Schema> is the name of the DBIC schema file written |
670 | to C<lib/MyApp/Schema.pm>. Because we specified C<create=dynamic> to |
671 | the helper, it use |
672 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to |
673 | dynamically load the schema information from the database every time |
c93b5eaa |
674 | the application starts. DBIC uses the schema to load other classes |
675 | that represent the tables in your database (DBIC refers to these |
676 | "table objects" as "result sources," see |
677 | L<DBIx::Class::ResultSource|DBIx::Class::ResultSource>). And finally, |
678 | C<dbi:SQLite:myapp.db> is the standard DBI connect string for use with |
679 | SQLite. |
3533daff |
680 | |
d0496197 |
681 | B<NOTE:> Although the C<create=dynamic> option to the DBIC helper |
19c49089 |
682 | makes for a nifty demonstration, is only really suitable for very |
683 | small applications. After this demonstration, you should almost always |
684 | use the C<create=static> option that we switch to below. |
dc9a0503 |
685 | |
686 | |
1390ef0e |
687 | =head1 ENABLE THE MODEL IN THE CONTROLLER |
688 | |
191dee29 |
689 | Open C<lib/MyApp/Controller/Books.pm> and un-comment the model code we |
690 | left disabled earlier (un-comment the line containing |
1390ef0e |
691 | C<[$c-E<gt>model('DB::Books')-E<gt>all]> and delete the next 2 lines): |
692 | |
693 | =head2 list |
694 | |
695 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
696 | |
697 | =cut |
698 | |
699 | sub list : Local { |
700 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
701 | # 'Context' that's used to 'glue together' the various components |
702 | # that make up the application |
703 | my ($self, $c) = @_; |
704 | |
705 | # Retrieve all of the book records as book model objects and store in the |
706 | # stash where they can be accessed by the TT template |
707 | $c->stash->{books} = [$c->model('DB::Books')->all]; |
708 | |
709 | # Set the TT template to use. You will almost always want to do this |
710 | # in your action methods (action methods respond to user input in |
711 | # your controllers). |
712 | $c->stash->{template} = 'books/list.tt2'; |
713 | } |
714 | |
c93b5eaa |
715 | B<TIP>: You may see the C<$c-E<gt>model('DB::Book')> un-commented |
716 | above written as C<$c-E<gt>model('DB')-E<gt>resultset('Book')>. The |
717 | two are equivalent. Either way, C<$c-E<gt>model> returns a |
718 | L<DBIx::Class::ResultSet|DBIx::Class::ResultSet> which handles queries |
719 | against the database and iterating over the set of results that are |
720 | returned. |
721 | |
722 | We are using the C<-E<gt>all> to fetch all of the books. DBIC |
723 | supports a wide variety of more advanced operations to easily do |
724 | things like filtering and sorting the results. For example, the |
518f3851 |
725 | following could be used to sort the results by descending title: |
c93b5eaa |
726 | |
727 | $c->model('DB::Books')->search({}, {order_by => 'title DESC'}); |
728 | |
729 | Some other examples are provided in |
730 | L<DBIx::Class::Manual::Cookbook/Complex WHERE clauses>, with |
731 | additional information found at L<DBIx::Class::ResultSet/search>, |
732 | L<DBIx::Class::Manual::FAQ/Searching>, |
733 | L<DBIx::Class::Manual::Intro|DBIx::Class::Manual::Intro> |
734 | and L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>. |
1390ef0e |
735 | |
736 | |
737 | =head2 Test Run The Application |
3533daff |
738 | |
739 | First, let's enable an environment variable option that causes |
740 | DBIx::Class to dump the SQL statements it's using to access the database |
741 | (this option can provide extremely helpful troubleshooting information): |
742 | |
743 | $ export DBIC_TRACE=1 |
744 | |
745 | This assumes you are using BASH as your shell -- adjust accordingly if |
746 | you are using a different shell (for example, under tcsh, use |
747 | C<setenv DBIC_TRACE 1>). |
748 | |
d0496197 |
749 | B<NOTE:> You can also set this in your code using |
3533daff |
750 | C<$class-E<gt>storage-E<gt>debug(1);>. See |
751 | L<DBIx::Class::Manual::Troubleshooting> for details (including options |
752 | to log to file instead of displaying to the Catalyst development server |
753 | log). |
754 | |
1390ef0e |
755 | Then launch the Catalyst development server. The log output should |
756 | display something like: |
3533daff |
757 | |
758 | $script/myapp_server.pl |
759 | [debug] Debug messages enabled |
1390ef0e |
760 | [debug] Statistics enabled |
3533daff |
761 | [debug] Loaded plugins: |
762 | .----------------------------------------------------------------------------. |
1390ef0e |
763 | | Catalyst::Plugin::ConfigLoader 0.20 | |
764 | | Catalyst::Plugin::StackTrace 0.08 | |
3533daff |
765 | | Catalyst::Plugin::Static::Simple 0.20 | |
766 | '----------------------------------------------------------------------------' |
767 | |
768 | [debug] Loaded dispatcher "Catalyst::Dispatcher" |
769 | [debug] Loaded engine "Catalyst::Engine::HTTP" |
770 | [debug] Found home "/home/me/MyApp" |
45d511e0 |
771 | [debug] Loaded Config "/home/me/MyApp/myapp.conf" |
3533daff |
772 | [debug] Loaded components: |
773 | .-----------------------------------------------------------------+----------. |
774 | | Class | Type | |
775 | +-----------------------------------------------------------------+----------+ |
776 | | MyApp::Controller::Books | instance | |
777 | | MyApp::Controller::Root | instance | |
d0496197 |
778 | | MyApp::Model::DB | instance | |
779 | | MyApp::Model::DB::Authors | class | |
780 | | MyApp::Model::DB::BookAuthors | class | |
781 | | MyApp::Model::DB::Books | class | |
3533daff |
782 | | MyApp::View::TT | instance | |
783 | '-----------------------------------------------------------------+----------' |
784 | |
785 | [debug] Loaded Private actions: |
786 | .----------------------+--------------------------------------+--------------. |
787 | | Private | Class | Method | |
788 | +----------------------+--------------------------------------+--------------+ |
789 | | /default | MyApp::Controller::Root | default | |
790 | | /end | MyApp::Controller::Root | end | |
1390ef0e |
791 | | /index | MyApp::Controller::Root | index | |
3533daff |
792 | | /books/index | MyApp::Controller::Books | index | |
793 | | /books/list | MyApp::Controller::Books | list | |
794 | '----------------------+--------------------------------------+--------------' |
795 | |
796 | [debug] Loaded Path actions: |
797 | .-------------------------------------+--------------------------------------. |
798 | | Path | Private | |
799 | +-------------------------------------+--------------------------------------+ |
1390ef0e |
800 | | / | /default | |
801 | | / | /index | |
802 | | /books | /books/index | |
3533daff |
803 | | /books/list | /books/list | |
804 | '-------------------------------------+--------------------------------------' |
805 | |
1390ef0e |
806 | [info] MyApp powered by Catalyst 5.7014 |
3533daff |
807 | You can connect to your server at http://localhost:3000 |
808 | |
1390ef0e |
809 | B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from |
810 | the 'base' directory of your application, not inside the C<script> |
811 | directory itself or it will not be able to locate the C<myapp.db> |
812 | database file. You can use a fully qualified or a relative path to |
813 | locate the database file, but we did not specify that when we ran the |
3533daff |
814 | model helper earlier. |
815 | |
816 | Some things you should note in the output above: |
817 | |
818 | =over 4 |
819 | |
1390ef0e |
820 | =item * |
3533daff |
821 | |
1390ef0e |
822 | Catalyst::Model::DBIC::Schema dynamically created three model classes, |
823 | one to represent each of the three tables in our database |
d0496197 |
824 | (C<MyApp::Model::DB::Authors>, C<MyApp::Model::DB::BookAuthors>, |
825 | and C<MyApp::Model::DB::Books>). |
3533daff |
826 | |
1390ef0e |
827 | =item * |
3533daff |
828 | |
829 | The "list" action in our Books controller showed up with a path of |
830 | C</books/list>. |
831 | |
832 | =back |
833 | |
834 | Point your browser to L<http://localhost:3000> and you should still get |
835 | the Catalyst welcome page. |
836 | |
837 | Next, to view the book list, change the URL in your browser to |
838 | L<http://localhost:3000/books/list>. You should get a list of the five |
1390ef0e |
839 | books loaded by the C<myapp01.sql> script above without any formatting. |
840 | The rating for each book should appear on each row, but the "Author(s)" |
191dee29 |
841 | column will still be blank (we will fill that in later). |
3533daff |
842 | |
843 | Also notice in the output of the C<script/myapp_server.pl> that DBIC |
844 | used the following SQL to retrieve the data: |
845 | |
846 | SELECT me.id, me.title, me.rating FROM books me |
847 | |
848 | because we enabled DBIC_TRACE. |
849 | |
0c51850e |
850 | You now have the beginnings of a simple but workable web application. |
3533daff |
851 | Continue on to future sections and we will develop the application |
852 | more fully. |
853 | |
854 | |
1390ef0e |
855 | =head1 CREATE A WRAPPER FOR THE VIEW |
856 | |
857 | When using TT, you can (and should!) create a wrapper that will |
858 | literally wrap content around each of your templates. This is |
859 | certainly useful as you have one main source for changing things that |
860 | will appear across your entire site/application instead of having to |
861 | edit many individual files. |
862 | |
863 | |
864 | =head2 Configure TT.pm For The Wrapper |
865 | |
866 | In order to create a wrapper, you must first edit your TT view and |
867 | tell it where to find your wrapper file. Your TT view is located in |
868 | C<lib/MyApp/View/TT.pm>. |
869 | |
870 | Edit C<lib/MyApp/View/TT.pm> and change it to match the following: |
871 | |
872 | __PACKAGE__->config( |
873 | # Change default TT extension |
874 | TEMPLATE_EXTENSION => '.tt2', |
875 | # Set the location for TT files |
876 | INCLUDE_PATH => [ |
c2dfb562 |
877 | MyApp->path_to( 'root', 'src' ), |
1390ef0e |
878 | ], |
879 | # Set to 1 for detailed timer stats in your HTML as comments |
880 | TIMER => 0, |
881 | # This is your wrapper template located in the 'root/src' |
882 | WRAPPER => 'wrapper.tt2', |
883 | ); |
884 | |
885 | |
886 | =head2 Create the Wrapper Template File and Stylesheet |
887 | |
888 | Next you need to set up your wrapper template. Basically, you'll want |
889 | to take the overall layout of your site and put it into this file. |
890 | For the tutorial, open C<root/src/wrapper.tt2> and input the following: |
891 | |
892 | <?xml version="1.0" encoding="UTF-8"?> |
893 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> |
894 | <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> |
895 | <head> |
896 | <title>[% template.title or "My Catalyst App!" %]</title> |
897 | <link rel="stylesheet" href="[% c.uri_for('/static/css/main.css') %]" /> |
898 | </head> |
899 | |
900 | <body> |
901 | <div id="outer"> |
902 | <div id="header"> |
903 | [%# Your logo could go here -%] |
904 | <img src="[% c.uri_for('/static/images/btn_88x31_powered.png') %]" /> |
905 | [%# Insert the page title -%] |
906 | <h1>[% template.title or site.title %]</h1> |
907 | </div> |
908 | |
909 | <div id="bodyblock"> |
910 | <div id="menu"> |
911 | Navigation: |
912 | <ul> |
913 | <li><a href="[% c.uri_for('/books/list') %]">Home</a></li> |
914 | <li><a href="[% c.uri_for('/') %]" title="Catalyst Welcome Page">Welcome</a></li> |
915 | <li><a href="mailto:nobody@nowhere.com" title="Contact Us">Contact Us</a></li> |
916 | </ul> |
917 | </div><!-- end menu --> |
918 | |
919 | <div id="content"> |
920 | [%# Status and error messages %] |
921 | <span class="message">[% status_msg %]</span> |
922 | <span class="error">[% error_msg %]</span> |
923 | [%# This is where TT will stick all of your template's contents. -%] |
924 | [% content %] |
925 | </div><!-- end content --> |
926 | </div><!-- end bodyblock --> |
927 | |
928 | <div id="footer">Copyright (c) your name goes here</div> |
c2dfb562 |
929 | </div><!-- end outer --> |
1390ef0e |
930 | |
931 | </body> |
932 | </html> |
933 | |
934 | Notice the status and error message sections in the code above: |
935 | |
936 | <span class="status">[% status_msg %]</span> |
937 | <span class="error">[% error_msg %]</span> |
938 | |
939 | If we set either message in the Catalyst stash (e.g., |
940 | C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it |
941 | will be displayed whenever any view used by that request is rendered. |
942 | The C<message> and C<error> CSS styles can be customized to suit your |
943 | needs in the C<root/static/css/main.css> file we create below. |
944 | |
945 | B<Notes:> |
946 | |
947 | =over 4 |
948 | |
949 | =item * |
950 | |
951 | The Catalyst stash only lasts for a single HTTP request. If |
952 | you need to retain information across requests you can use |
953 | L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use |
954 | Catalyst sessions in the Authentication part of the tutorial). |
955 | |
956 | =item * |
957 | |
958 | Although it is beyond the scope of this tutorial, you may wish to use |
959 | a JavaScript or AJAX tool such as jQuery (L<http://www.jquery.com>) or |
960 | Dojo (L<http://www.dojotoolkit.org>). |
961 | |
962 | =back |
963 | |
964 | |
965 | =head3 Create A Basic Stylesheet |
966 | |
967 | First create a central location for stylesheets under the static |
968 | directory: |
969 | |
970 | $ mkdir root/static/css |
971 | |
972 | Then open the file C<root/static/css/main.css> (the file referenced in |
973 | the stylesheet href link of our wrapper above) and add the following |
974 | content: |
975 | |
976 | #header { |
977 | text-align: center; |
978 | } |
979 | #header h1 { |
980 | margin: 0; |
981 | } |
982 | #header img { |
983 | float: right; |
984 | } |
985 | #footer { |
986 | text-align: center; |
987 | font-style: italic; |
988 | padding-top: 20px; |
989 | } |
990 | #menu { |
991 | font-weight: bold; |
992 | background-color: #ddd; |
993 | } |
994 | #menu ul { |
995 | list-style: none; |
996 | float: left; |
997 | margin: 0; |
998 | padding: 0 0 50% 5px; |
999 | font-weight: normal; |
1000 | background-color: #ddd; |
1001 | width: 100px; |
1002 | } |
1003 | #content { |
1004 | margin-left: 120px; |
1005 | } |
1006 | .message { |
1007 | color: #390; |
1008 | } |
1009 | .error { |
1010 | color: #f00; |
1011 | } |
1012 | |
1013 | You may wish to check out a "CSS Framework" like Emastic |
1014 | (L<http://code.google.com/p/emastic/>) as a way to quickly |
1015 | provide lots of high-quality CSS functionality. |
1016 | |
1017 | |
1018 | =head2 Test Run The Application |
1019 | |
1020 | Restart the development server and hit "Reload" in your web browser |
1021 | and you should now see a formatted version of our basic book list. |
1022 | Although our wrapper and stylesheet are obviously very simple, you |
1023 | should see how it allows us to control the overall look of an entire |
1024 | website from two central files. To add new pages to the site, just |
1025 | provide a template that fills in the C<content> section of our wrapper |
1026 | template -- the wrapper will provide the overall feel of the page. |
1027 | |
1028 | |
3533daff |
1029 | =head1 A STATIC DATABASE MODEL WITH C<DBIx::Class> |
1030 | |
1031 | =head2 Create Static DBIC Schema Files |
1032 | |
1390ef0e |
1033 | Unlike the previous DBIC section where we had C<create=dynamic> |
1034 | automatically discover the structure of the database every time the |
1035 | application started, here we will use static schema files for more |
1036 | control. This is typical of most "real world" applications. |
3533daff |
1037 | |
1390ef0e |
1038 | One option would be to manually create a separate schema file for each |
1039 | table in the database, however, lets use the same |
1040 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> used |
1041 | earlier with C<create=dynamic> to build the static files for us. |
9ad715b3 |
1042 | First, lets remove the schema file created earlier: |
3533daff |
1043 | |
1390ef0e |
1044 | $ rm lib/MyApp/Schema.pm |
3533daff |
1045 | |
1046 | Now regenerate the schema using the C<create=static> option: |
1047 | |
d0496197 |
1048 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema create=static dbi:SQLite:myapp.db |
1049 | exists "/home/kclark/dev/MyApp/script/../lib/MyApp/Model" |
1050 | exists "/home/kclark/dev/MyApp/script/../t" |
1051 | Dumping manual schema for MyApp::Schema to directory /home/kclark/dev/MyApp/script/../lib ... |
3533daff |
1052 | Schema dump completed. |
d0496197 |
1053 | exists "/home/kclark/dev/MyApp/script/../lib/MyApp/Model/DB.pm" |
3533daff |
1054 | |
1390ef0e |
1055 | We could have also deleted C<lib/MyApp/Model/DB.pm>, but it would |
3533daff |
1056 | have regenerated the same file (note the C<exists> in the output above). |
d0496197 |
1057 | If you take a look at C<lib/MyApp/Model/DB.pm>, it simply contains |
1058 | a reference to the actual schema file in C<lib/MyApp/Schema.pm> |
3533daff |
1059 | along with the database connect string. |
1060 | |
1390ef0e |
1061 | If you look in the C<lib/MyApp/Schema.pm> file, you will find that it |
1062 | is no longer using |
1063 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> as its base |
1064 | class (L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> is |
1065 | only being used by the helper to load the schema once and then create |
1066 | the static files for us) and C<Schema.pm> only contains a call to the |
c2dfb562 |
1067 | C<load_classes> method. You will also find that C<lib/MyApp> |
1390ef0e |
1068 | contains a C<Schema> subdirectory, with one file inside this directory |
1069 | for each of the tables in our simple database (C<Authors.pm>, |
1070 | C<BookAuthors.pm>, and C<Books.pm>). These three files were created |
1071 | based on the information found by |
1072 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> as the |
1073 | helper ran. |
1074 | |
1075 | The idea with all of the files created under C<lib/MyApp/Schema> by |
1076 | the C<create=static> option is to only edit the files below the C<# DO |
1077 | NOT MODIFY THIS OR ANYTHING ABOVE!> warning. If you place all of your |
3533daff |
1078 | changes below that point in the file, you can regenerate the |
1390ef0e |
1079 | automatically created information at the top of each file should your |
1080 | database structure get updated. |
3533daff |
1081 | |
1390ef0e |
1082 | Also note the "flow" of the model information across the various files |
1083 | and directories. Catalyst will initially load the model from |
d0496197 |
1084 | C<lib/MyApp/Model/DB.pm>. This file contains a reference to |
1085 | C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, |
1390ef0e |
1086 | the call to C<load_classes> in C<Schema.pm> will load each of the |
d0496197 |
1087 | table-specific "results source" files from the C<lib/MyApp/Schema> |
1390ef0e |
1088 | subdirectory. These three table-specific DBIC schema files will then be |
1089 | used to create three table-specific Catalyst models every time the |
3533daff |
1090 | application starts (you can see these three model files listed in |
1091 | the debug output generated when you launch the application). |
1092 | |
1093 | |
1094 | =head2 Updating the Generated DBIC Schema Files |
1095 | |
3533daff |
1096 | Let's manually add some relationship information to the auto-generated |
d0496197 |
1097 | schema files. First edit C<lib/MyApp/Schema/Books.pm> and |
1390ef0e |
1098 | add the following text below the C<# You can replace this text...> |
3533daff |
1099 | comment: |
1100 | |
1101 | # |
1102 | # Set relationships: |
1390ef0e |
1103 | # |
3533daff |
1104 | |
1105 | # has_many(): |
1106 | # args: |
1107 | # 1) Name of relationship, DBIC will create accessor with this name |
1108 | # 2) Name of the model class referenced by this relationship |
1109 | # 3) Column name in *foreign* table |
d0496197 |
1110 | __PACKAGE__->has_many(book_authors => 'MyApp::Schema::BookAuthors', 'book_id'); |
3533daff |
1111 | |
1112 | # many_to_many(): |
1113 | # args: |
1114 | # 1) Name of relationship, DBIC will create accessor with this name |
1390ef0e |
1115 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
1116 | # 3) Name of belongs_to() relationship in model class of has_many() above |
3533daff |
1117 | # You must already have the has_many() defined to use a many_to_many(). |
1118 | __PACKAGE__->many_to_many(authors => 'book_authors', 'author'); |
1119 | |
1120 | |
1121 | B<Note:> Be careful to put this code I<above> the C<1;> at the end of the |
1122 | file. As with any Perl package, we need to end the last line with |
1123 | a statement that evaluates to C<true>. This is customarily done with |
1124 | C<1;> on a line by itself. |
1125 | |
1390ef0e |
1126 | This code defines both a C<has_many> and a C<many_to_many> relationship. |
1127 | The C<many_to_many> relationship is optional, but it makes it easier to |
1128 | map a book to its collection of authors. Without it, we would have to |
1129 | "walk" though the C<book_authors> table as in |
1130 | C<$book-E<gt>book_authors-E<gt>first-E<gt>author-E<gt>last_name> |
1131 | (we will see examples on how to use DBIC objects in your code soon, |
1132 | but note that because C<$book-E<gt>book_authors> can return multiple |
1133 | authors, we have to use C<first> to display a single author). |
1134 | C<many_to_many> allows us to use the shorter |
1135 | C<$book-E<gt>authors-E<gt>first-E<gt>last_name>. |
1136 | Note that you cannot define a C<many_to_many> relationship without |
1137 | also having the C<has_many> relationship in place. |
3533daff |
1138 | |
d0496197 |
1139 | Then edit C<lib/MyApp/Schema/Authors.pm> and add relationship |
3533daff |
1140 | information as follows (again, be careful to put in above the C<1;> but |
1141 | below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> comment): |
1142 | |
1143 | # |
1144 | # Set relationships: |
1145 | # |
1146 | |
1147 | # has_many(): |
1148 | # args: |
1149 | # 1) Name of relationship, DBIC will create accessor with this name |
1150 | # 2) Name of the model class referenced by this relationship |
1151 | # 3) Column name in *foreign* table |
d0496197 |
1152 | __PACKAGE__->has_many(book_author => 'MyApp::Schema::BookAuthors', 'author_id'); |
3533daff |
1153 | |
1154 | # many_to_many(): |
1155 | # args: |
1156 | # 1) Name of relationship, DBIC will create accessor with this name |
1157 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
1390ef0e |
1158 | # 3) Name of belongs_to() relationship in model class of has_many() above |
3533daff |
1159 | # You must already have the has_many() defined to use a many_to_many(). |
1160 | __PACKAGE__->many_to_many(books => 'book_author', 'book'); |
1161 | |
1390ef0e |
1162 | Finally, do the same for the "join table," |
d0496197 |
1163 | C<lib/MyApp/Schema/BookAuthors.pm>: |
3533daff |
1164 | |
1165 | # |
1166 | # Set relationships: |
1167 | # |
1168 | |
1169 | # belongs_to(): |
1170 | # args: |
1171 | # 1) Name of relationship, DBIC will create accessor with this name |
1172 | # 2) Name of the model class referenced by this relationship |
1173 | # 3) Column name in *this* table |
d0496197 |
1174 | __PACKAGE__->belongs_to(book => 'MyApp::Schema::Books', 'book_id'); |
3533daff |
1175 | |
1176 | # belongs_to(): |
1177 | # args: |
1178 | # 1) Name of relationship, DBIC will create accessor with this name |
1179 | # 2) Name of the model class referenced by this relationship |
1180 | # 3) Column name in *this* table |
d0496197 |
1181 | __PACKAGE__->belongs_to(author => 'MyApp::Schema::Authors', 'author_id'); |
3533daff |
1182 | |
1183 | |
1390ef0e |
1184 | =head2 Run The Application |
3533daff |
1185 | |
1186 | Run the Catalyst "demo server" script with the C<DBIC_TRACE> option |
1187 | (it might still be enabled from earlier in the tutorial, but here |
1188 | is an alternate way to specify the option just in case): |
1189 | |
1190 | $ DBIC_TRACE=1 script/myapp_server.pl |
1191 | |
1390ef0e |
1192 | Make sure that the application loads correctly and that you see the |
1193 | three dynamically created model class (one for each of the |
3533daff |
1194 | table-specific schema classes we created). |
1195 | |
c2dfb562 |
1196 | Then hit the URL L<http://localhost:3000/books/list> and be sure that |
1197 | the book list is displayed via the relationships established above. You |
1198 | can leave the development server running for the next step if you wish. |
3533daff |
1199 | |
c2dfb562 |
1200 | B<Note:> You will not see the authors yet because the view does not yet |
1201 | use the new relations. Read on to the next section where we update the |
1202 | template to do that. |
3533daff |
1203 | |
1204 | |
1205 | =head1 UPDATING THE VIEW |
1206 | |
1207 | Let's add a new column to our book list page that takes advantage of |
1208 | the relationship information we manually added to our schema files |
1209 | in the previous section. Edit C<root/src/books/list.tt2> add add the |
1210 | following code below the existing table cell that contains |
1390ef0e |
1211 | C<book.rating> (IOW, add a new table cell below the existing two |
3533daff |
1212 | C<td> cells): |
1213 | |
1214 | <td> |
1215 | [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%] |
1216 | [% # loop in 'side effect notation' to load just the last names of the -%] |
a0c5188a |
1217 | [% # authors into the list. Note that the 'push' TT vmethod does not print -%] |
3533daff |
1218 | [% # a value, so nothing will be printed here. But, if you have something -%] |
1219 | [% # in TT that does return a method and you don't want it printed, you -%] |
1220 | [% # can: 1) assign it to a bogus value, or 2) use the CALL keyword to -%] |
1221 | [% # call it and discard the return value. -%] |
1222 | [% tt_authors = [ ]; |
1223 | tt_authors.push(author.last_name) FOREACH author = book.authors %] |
1224 | [% # Now use a TT 'virtual method' to display the author count in parens -%] |
1225 | [% # Note the use of the TT filter "| html" to escape dangerous characters -%] |
1226 | ([% tt_authors.size | html %]) |
1227 | [% # Use another TT vmethod to join & print the names & comma separators -%] |
1228 | [% tt_authors.join(', ') | html %] |
1229 | </td> |
1230 | |
1390ef0e |
1231 | Then hit "Reload" in your browser (note that you don't need to reload |
3533daff |
1232 | the development server or use the C<-r> option when updating TT |
1390ef0e |
1233 | templates) and you should now see the number of authors each book has |
1234 | along with a comma-separated list of the authors' last names. (If you |
1235 | didn't leave the development server running from the previous step, |
1236 | you will obviously need to start it before you can refresh your |
1237 | browser window.) |
1238 | |
1239 | If you are still running the development server with C<DBIC_TRACE> |
1240 | enabled, you should also now see five more C<SELECT> statements in the |
1241 | debug output (one for each book as the authors are being retrieved by |
3533daff |
1242 | DBIC). |
1243 | |
c2dfb562 |
1244 | SELECT me.id, me.title, me.rating FROM books me: |
1245 | SELECT me.book_id, me.author_id FROM book_authors me WHERE ( me.book_id = ? ): '1' |
1246 | SELECT me.book_id, me.author_id FROM book_authors me WHERE ( me.book_id = ? ): '2' |
1247 | SELECT me.book_id, me.author_id FROM book_authors me WHERE ( me.book_id = ? ): '3' |
1248 | SELECT me.book_id, me.author_id FROM book_authors me WHERE ( me.book_id = ? ): '4' |
1249 | SELECT me.book_id, me.author_id FROM book_authors me WHERE ( me.book_id = ? ): '5' |
1250 | |
1251 | Also note in C<root/src/books/list.tt2> that we are using "| html", a |
1252 | type of TT filter, to escape characters such as E<lt> and E<gt> to < |
1253 | and > and avoid various types of dangerous hacks against your |
1254 | application. In a real application, you would probably want to put |
1255 | "| html" at the end of every field where a user has control over the |
1256 | information that can appear in that field (and can therefore inject |
1257 | markup or code if you don't "neutralize" those fields). In addition to |
1258 | "| html", Template Toolkit has a variety of other useful filters that |
1259 | can found in the documentation for |
1260 | L<Template::Filters|Template::Filters>. |
3533daff |
1261 | |
1262 | |
1390ef0e |
1263 | =head1 RUNNING THE APPLICATION FROM THE COMMAND LINE |
1264 | |
1265 | In some situations, it can be useful to run your application and |
1266 | display a page without using a browser. Catalyst lets you do this |
1267 | using the C<scripts/myapp_test.pl> script. Just supply the URL you |
1268 | wish to display and it will run that request through the normal |
1269 | controller dispatch logic and use the appropriate view to render the |
1270 | output (obviously, complex pages may dump a lot of text to your |
1271 | terminal window). For example, if you type: |
1272 | |
1273 | $ script/myapp_test.pl "/books/list" |
1274 | |
1275 | You should get the same text as if you visited |
1276 | L<http://localhost:3000/books/list> with the normal development server |
1277 | and asked your browser to view the page source. |
3533daff |
1278 | |
1390ef0e |
1279 | |
1280 | =head1 OPTIONAL INFORMATION |
1281 | |
1282 | B<NOTE: The rest of this part of the tutorial is optional. You can |
1283 | skip to Part 4, L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>, |
3533daff |
1284 | if you wish.> |
1285 | |
1390ef0e |
1286 | =head2 Using C<RenderView> for the Default View |
1287 | |
1288 | Once your controller logic has processed the request from a user, it |
1289 | forwards processing to your view in order to generate the appropriate |
3533daff |
1290 | response output. Catalyst uses |
1390ef0e |
1291 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by |
1292 | default to automatically performs this operation. If you look in |
1293 | C<lib/MyApp/Controller/Root.pm>, you should see the empty |
3533daff |
1294 | definition for the C<sub end> method: |
1295 | |
1296 | sub end : ActionClass('RenderView') {} |
1297 | |
1390ef0e |
1298 | The following bullet points provide a quick overview of the |
3533daff |
1299 | C<RenderView> process: |
1300 | |
1301 | =over 4 |
1302 | |
1303 | =item * |
1304 | |
1305 | C<Root.pm> is designed to hold application-wide logic. |
1306 | |
1307 | =item * |
1308 | |
1390ef0e |
1309 | At the end of a given user request, Catalyst will call the most specific |
1310 | C<end> method that's appropriate. For example, if the controller for a |
1311 | request has an C<end> method defined, it will be called. However, if |
1312 | the controller does not define a controller-specific C<end> method, the |
3533daff |
1313 | "global" C<end> method in C<Root.pm> will be called. |
1314 | |
1315 | =item * |
1316 | |
1317 | Because the definition includes an C<ActionClass> attribute, the |
1318 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic |
1319 | will be executed B<after> any code inside the definition of C<sub end> |
1320 | is run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions> |
1321 | for more information on C<ActionClass>. |
1322 | |
1323 | =item * |
1324 | |
1390ef0e |
1325 | Because C<sub end> is empty, this effectively just runs the default |
1326 | logic in C<RenderView>. However, you can easily extend the |
1327 | C<RenderView> logic by adding your own code inside the empty method body |
1328 | (C<{}>) created by the Catalyst Helpers when we first ran the |
1329 | C<catalyst.pl> to initialize our application. See |
1330 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more |
3533daff |
1331 | detailed information on how to extended C<RenderView> in C<sub end>. |
1332 | |
1333 | =back |
1334 | |
1335 | |
1336 | =head2 Using The Default Template Name |
1337 | |
1390ef0e |
1338 | By default, C<Catalyst::View::TT> will look for a template that uses the |
1339 | same name as your controller action, allowing you to save the step of |
1340 | manually specifying the template name in each action. For example, this |
1341 | would allow us to remove the |
1342 | C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our |
1343 | C<list> action in the Books controller. Open |
3533daff |
1344 | C<lib/MyApp/Controller/Books.pm> in your editor and comment out this line |
1345 | to match the following (only the C<$c-E<gt>stash-E<gt>{template}> line |
1346 | has changed): |
1347 | |
1348 | =head2 list |
1349 | |
1350 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
1351 | |
1352 | =cut |
1353 | |
1354 | sub list : Local { |
1355 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
1356 | # 'Context' that's used to 'glue together' the various components |
1357 | # that make up the application |
1358 | my ($self, $c) = @_; |
1359 | |
1360 | # Retrieve all of the book records as book model objects and store in the |
1361 | # stash where they can be accessed by the TT template |
d0496197 |
1362 | $c->stash->{books} = [$c->model('DB::Books')->all]; |
3533daff |
1363 | |
1364 | # Set the TT template to use. You will almost always want to do this |
1365 | # in your action methods (actions methods respond to user input in |
1366 | # your controllers). |
1367 | #$c->stash->{template} = 'books/list.tt2'; |
1368 | } |
1369 | |
3533daff |
1370 | |
1390ef0e |
1371 | You should now be able to restart the development server as per the |
3533daff |
1372 | previous section and access the L<http://localhost:3000/books/list> |
1373 | as before. |
1374 | |
1375 | B<NOTE:> Please note that if you use the default template technique, |
1376 | you will B<not> be able to use either the C<$c-E<gt>forward> or |
1390ef0e |
1377 | the C<$c-E<gt>detach> mechanisms (these are discussed in Part 2 and |
3533daff |
1378 | Part 9 of the Tutorial). |
1379 | |
1380 | |
1381 | =head2 Return To A Manually-Specified Template |
1382 | |
1383 | In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach> |
1384 | later in the tutorial, you should remove the comment from the |
1385 | statement in C<sub list> in C<lib/MyApp/Controller/Books.pm>: |
1386 | |
1387 | $c->stash->{template} = 'books/list.tt2'; |
1388 | |
1390ef0e |
1389 | Then delete the C<TEMPLATE_EXTENSION> line in |
3533daff |
1390 | C<lib/MyApp/View/TT.pm>. |
1391 | |
1390ef0e |
1392 | You should then be able to restart the development server and |
3533daff |
1393 | access L<http://localhost:3000/books/list> in the same manner as |
1394 | with earlier sections. |
1395 | |
1396 | |
1397 | =head1 AUTHOR |
1398 | |
1399 | Kennedy Clark, C<hkclark@gmail.com> |
1400 | |
1401 | Please report any errors, issues or suggestions to the author. The |
1402 | most recent version of the Catalyst Tutorial can be found at |
82ab4bbf |
1403 | L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>. |
3533daff |
1404 | |
45c7830f |
1405 | Copyright 2006-2008, Kennedy Clark, under Creative Commons License |
8482d557 |
1406 | (L<http://creativecommons.org/licenses/by-sa/3.0/us/>). |