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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 or in a directory that already has a "MyApp" subdirectory): |
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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, be aware |
145 | that Catalyst changed the default format from YAML to the more |
146 | straightforward C<Config::General> style. This tutorial uses the |
147 | newer C<myapp.conf> file for C<Config::General>. However, Catalyst |
148 | supports both formats and will automatically use either C<myapp.conf> |
149 | or C<myapp.yml> (or any other format supported by |
150 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> and |
151 | L<Config::Any|Config::Any>). If you are using a version of |
152 | Catalyst::Devel prior to 1.06, you can convert to the newer format by |
153 | simply creating the C<myapp.conf> file manually and deleting |
154 | C<myapp.yml>. The default contents of the C<myapp.conf> you create |
155 | should only consist of one line: |
156 | |
157 | name MyApp |
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158 | |
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159 | B<TIP>: This script can be useful for converting between configuration |
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160 | formats: |
161 | |
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162 | perl -Ilib -e 'use MyApp; use Config::General; |
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163 | Config::General->new->save_file("myapp.conf", MyApp->config);' |
164 | |
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165 | =item * |
166 | |
167 | L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple> |
168 | |
169 | C<Static::Simple> provides an easy method of serving static content such |
170 | as images and CSS files under the development server. |
171 | |
172 | =back |
173 | |
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174 | For our application, we want to add one new plugin into the mix. To |
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175 | do this, edit C<lib/MyApp.pm> (this file is generally referred to as |
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176 | your I<application class>) and delete the lines with: |
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177 | |
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178 | use Catalyst qw/-Debug |
179 | ConfigLoader |
180 | Static::Simple/; |
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181 | |
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182 | Then replace it with: |
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183 | |
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184 | # Load plugins |
185 | use Catalyst qw/-Debug |
186 | ConfigLoader |
187 | Static::Simple |
188 | |
189 | StackTrace |
190 | /; |
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191 | |
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192 | B<Note:> Recent versions of C<Catalyst::Devel> have used a variety of |
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193 | techniques to load these plugins/flags. For example, you might see |
194 | the following: |
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195 | |
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196 | __PACKAGE__->setup(qw/-Debug ConfigLoader Static::Simple/); |
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197 | |
198 | Don't let these variations confuse you -- they all accomplish the same |
199 | result. |
200 | |
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201 | This tells Catalyst to start using one new plugin, |
202 | L<Catalyst::Plugin::StackTrace|Catalyst::Plugin::StackTrace>, to add a |
203 | stack trace to the standard Catalyst "debug screen" (the screen |
204 | Catalyst sends to your browser when an error occurs). Be aware that |
205 | L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your |
206 | browser, not in the console window from which you're running your |
207 | application, which is where logging output usually goes. |
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208 | |
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209 | B<Notes:> |
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210 | |
211 | =over 4 |
212 | |
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213 | =item * |
214 | |
215 | C<__PACKAGE__> is just a shorthand way of referencing the name of the |
216 | package where it is used. Therefore, in C<MyApp.pm>, C<__PACKAGE__> |
217 | is equivalent to C<MyApp>. |
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218 | |
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219 | =item * |
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220 | |
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221 | You will want to disable L<StackTrace|Catalyst::Plugin::StackTrace> |
222 | before you put your application into production, but it can be helpful |
223 | during development. |
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224 | |
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225 | =item * |
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226 | |
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227 | When specifying plugins on the C<__PACKAGE__-E<gt>setup> line, you can |
228 | omit C<Catalyst::Plugin::> from the name. Additionally, you can |
229 | spread the plugin names across multiple lines as shown here, or place |
230 | them all on one (or more) lines as with the default configuration. |
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231 | |
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232 | =back |
233 | |
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234 | |
235 | =head1 CREATE A CATALYST CONTROLLER |
236 | |
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237 | As discussed earlier, controllers are where you write methods that |
238 | interact with user input. Typically, controller methods respond to |
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239 | C<GET> and C<POST> messages from the user's web browser. |
240 | |
241 | Use the Catalyst C<create> script to add a controller for book-related |
242 | actions: |
243 | |
244 | $ script/myapp_create.pl controller Books |
245 | exists "/home/me/MyApp/script/../lib/MyApp/Controller" |
246 | exists "/home/me/MyApp/script/../t" |
247 | created "/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm" |
248 | created "/home/me/MyApp/script/../t/controller_Books.t" |
249 | |
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250 | Then edit C<lib/MyApp/Controller/Books.pm> (as discussed in Part 2 of |
251 | the Tutorial, Catalyst has a separate directory under C<lib/MyApp> for |
252 | each of the three parts of MVC: C<Model>, C<View>, and C<Controller>) |
253 | and add the following method to the controller: |
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254 | |
255 | =head2 list |
256 | |
257 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
258 | |
259 | =cut |
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260 | |
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261 | sub list : Local { |
262 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
263 | # 'Context' that's used to 'glue together' the various components |
264 | # that make up the application |
265 | my ($self, $c) = @_; |
266 | |
267 | # Retrieve all of the book records as book model objects and store in the |
268 | # stash where they can be accessed by the TT template |
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269 | # $c->stash->{books} = [$c->model('DB::Books')->all]; |
270 | # But, for now, use this code until we create the model later |
271 | $c->stash->{books} = ''; |
272 | |
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273 | # Set the TT template to use. You will almost always want to do this |
274 | # in your action methods (action methods respond to user input in |
275 | # your controllers). |
276 | $c->stash->{template} = 'books/list.tt2'; |
277 | } |
278 | |
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279 | B<TIP>: See Appendix 1 for tips on removing the leading spaces when |
280 | cutting and pasting example code from POD-based documents. |
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281 | |
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282 | Programmers experienced with object-oriented Perl should recognize |
283 | C<$self> as a reference to the object where this method was called. |
284 | On the other hand, C<$c> will be new to many Perl programmers who have |
285 | not used Catalyst before (it's sometimes written as C<$context>). The |
286 | Context object is automatically passed to all Catalyst components. It |
287 | is used to pass information between components and provide access to |
288 | Catalyst and plugin functionality. |
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289 | |
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290 | Catalyst actions are regular Perl methods, but they make use of |
291 | attributes (the "C<: Local>" next to the "C<sub list>" in the code |
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292 | above) to provide additional information to the Catalyst dispatcher |
293 | logic (note that the space between the colon and the attribute name is |
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294 | optional... you will see attributes written both ways). Most Catalyst |
295 | Controllers use one of five action types: |
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296 | |
297 | =over 4 |
298 | |
299 | =item * |
300 | |
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301 | B<:Private> -- Use C<:Private> for methods that you want to make into |
302 | an action, but you do not want Catalyst to directly expose the action |
303 | to your users. Catalyst will not map C<:Private> methods to a URI. |
304 | Use them for various sorts of "special" methods (the C<begin>, |
305 | C<auto>, etc. discussed below) or for methods you want to be able to |
306 | C<forward> or C<detach> to. (If the method is a plain old "helper |
307 | method" that you don't want to be an action at all, then just define |
308 | the method without any attribute -- you can call it in your code, but |
309 | the Catalyst dispatcher will ignore it.) |
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310 | |
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311 | There are five types of "special" build-in C<:Private> actions: |
312 | C<begin>, C<end>, C<default>, C<index>, and C<auto>. |
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313 | |
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314 | =over 4 |
315 | |
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316 | =item * |
317 | |
318 | With C<begin>, C<end>, C<default>, C<index> private actions, only the |
319 | most specific action of each type will be called. For example, if you |
320 | define a C<begin> action in your controller it will I<override> a |
321 | C<begin> action in your application/root controller -- I<only> the |
322 | action in your controller will be called. |
323 | |
324 | =item * |
325 | |
326 | Unlike the other actions where only a single method is called for each |
327 | request, I<every> auto action along the chain of namespaces will be |
328 | called. Each C<auto> action will be called I<from the application/root |
329 | controller down through the most specific class>. |
330 | |
331 | =back |
332 | |
333 | =item * |
334 | |
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335 | B<:Path> -- C<:Path> actions let you map a method to an explicit URI |
336 | path. For example, "C<:Path('list')>" in |
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337 | C<lib/MyApp/Controller/Books.pm> would match on the URL |
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338 | C<http://localhost:3000/books/list> but "C<:Path('/list')>" would match |
339 | on C<http://localhost:3000/list>. You can use C<:Args()> to specify |
340 | how many arguments an action should except. See |
341 | L<Catalyst::Manual::Intro/Action_types> for more information and a few |
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342 | examples. |
343 | |
344 | =item * |
345 | |
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346 | B<:Local> -- C<:Local> is merely a shorthand for |
347 | "C<:Path('_name_of_method_')>". For example, these are equivalent: |
348 | "C<sub create_book :Local {...}>" and |
349 | "C<sub create_book :Path('create_book') {...}>". |
350 | |
351 | =item * |
352 | |
353 | B<:Global> -- C<:Global> is merely a shorthand for |
354 | "C<:Path('/_name_of_method_')>". For example, these are equivalent: |
355 | "C<sub create_book :Global {...}>" and |
356 | "C<sub create_book :Path('/create_book') {...}>". |
357 | |
358 | =item * |
359 | |
360 | B<:Chained> -- Newer Catalyst applications tend to use the Chained |
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361 | dispatch form of action types because of its power and flexibility. |
362 | It allows a series of controller methods to automatically be dispatched |
363 | to service a single user request. See |
364 | L<Catalyst::Manual::Tutorial::BasicCRUD|Catalyst::Manual::Tutorial::BasicCRUD> |
365 | and L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained> |
366 | for more information on chained actions. |
367 | |
368 | =back |
369 | |
370 | You should refer to L<Catalyst::Manual::Intro/Action_types> for |
371 | additional information and for coverage of some lesser-used action |
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372 | types not discussed here (C<Regex> and C<LocalRegex>). |
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373 | |
374 | |
375 | =head1 CATALYST VIEWS |
376 | |
377 | As mentioned in Part 2 of the tutorial, views are where you render |
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378 | output, typically for display in the user's web browser (but also |
379 | possibly using other display output-generation systems). The code in |
380 | C<lib/MyApp/View> selects the I<type> of view to use, with the actual |
381 | rendering template found in the C<root> directory. As with virtually |
382 | every aspect of Catalyst, options abound when it comes to the specific |
383 | view technology you adopt inside your application. However, most |
384 | Catalyst applications use the Template Toolkit, known as TT (for more |
385 | information on TT, see L<http://www.template-toolkit.org>). Other |
386 | somewhat popular view technologies include Mason |
387 | (L<http://www.masonhq.com> and L<http://www.masonbook.com>) and |
388 | L<HTML::Template> (L<http://html-template.sourceforge.net>). |
389 | |
390 | |
391 | =head2 Create a Catalyst View |
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392 | |
393 | When using TT for the Catalyst view, there are two main helper scripts: |
394 | |
395 | =over 4 |
396 | |
397 | =item * |
398 | |
399 | L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT> |
400 | |
401 | =item * |
402 | |
403 | L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite> |
404 | |
405 | =back |
406 | |
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407 | Both helpers are similar. C<TT> creates the C<lib/MyApp/View/TT.pm> |
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408 | file and leaves the creation of any hierarchical template organization |
409 | entirely up to you. (It also creates a C<t/view_TT.t> file for testing; |
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410 | test cases will be discussed in Part 8.) C<TTSite>, on the other hand, |
411 | creates a modular and hierarchical view layout with |
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412 | separate Template Toolkit (TT) files for common header and footer |
413 | information, configuration values, a CSS stylesheet, and more. |
414 | |
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415 | While C<TTSite> was useful to bootstrap a project, its use is now |
416 | deprecated and to be considered historical. For most Catalyst |
417 | applications it adds redundant functionality and structure; many in the |
418 | Catalyst community recommend that it's easier to learn both Catalyst and |
419 | Template Toolkit if you use the more basic C<TT> approach. |
420 | Consequently, this tutorial will use "plain old TT." |
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421 | |
422 | Enter the following command to enable the C<TT> style of view |
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423 | rendering for this tutorial: |
424 | |
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425 | $ script/myapp_create.pl view TT TT |
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426 | exists "/home/me/MyApp/script/../lib/MyApp/View" |
427 | exists "/home/me/MyApp/script/../t" |
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428 | created "/home/me/MyApp/script/../lib/MyApp/View/TT.pm" |
429 | created "/home/me/MyApp/script/../t/view_TT.t" |
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430 | |
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431 | This simply creates a view called C<TT> (the second 'TT' argument) in |
432 | a file called C<TT.pm> (the first 'TT' argument). It is now up to you |
433 | to decide how you want to structure your view layout. For the |
434 | tutorial, we will start with a very simple TT template to initially |
435 | demonstrate the concepts, but quickly migrate to a more typical |
436 | "wrapper page" type of configuration (where the "wrapper" controls the |
437 | overall "look and feel" of your site from a single file or set of |
438 | files). |
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439 | |
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440 | Edit C<lib/MyApp/View/TT.pm> and you should see that the default |
441 | contents contains something similar to the following: |
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442 | |
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443 | __PACKAGE__->config(TEMPLATE_EXTENSION => '.tt'); |
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444 | |
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445 | And update it to match: |
446 | |
447 | __PACKAGE__->config( |
448 | # Change default TT extension |
449 | TEMPLATE_EXTENSION => '.tt2', |
450 | # Set the location for TT files |
451 | INCLUDE_PATH => [ |
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452 | MyApp->path_to( 'root', 'src' ), |
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453 | ], |
454 | ); |
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455 | |
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456 | B<NOTE:> Make sure to add a comma after '.tt2' outside the single |
457 | quote. |
458 | |
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459 | This changes the default extension for Template Toolkit from '.tt' to |
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460 | '.tt2' and changes the base directory for your template files from |
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461 | C<root> to C<root/src>. These changes from the default are done mostly |
462 | to facilitate the application we're developing in this tutorial; as with |
463 | most things Perl, there's more than one way to do it... |
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464 | |
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465 | B<Note:> We will use C<root/src> as the base directory for our |
466 | template files, which a full naming convention of |
467 | C<root/src/_controller_name_/_action_name_.tt2>. Another popular option is to |
468 | use C<root/> as the base (with a full filename pattern of |
469 | C<root/_controller_name_/_action_name_.tt2>). |
470 | |
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471 | |
472 | =head2 Create a TT Template Page |
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473 | |
474 | First create a directory for book-related TT templates: |
475 | |
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476 | $ mkdir -p root/src/books |
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477 | |
478 | Then create C<root/src/books/list.tt2> in your editor and enter: |
479 | |
480 | [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%] |
481 | [% # see this "chomping" in your browser because HTML ignores blank lines, but -%] |
482 | [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%] |
483 | [%- # optional, but both the beginning and the ending TT tags support chomping. -%] |
484 | |
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485 | [% # Provide a title -%] |
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486 | [% META title = 'Book List' -%] |
487 | |
488 | <table> |
489 | <tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr> |
490 | [% # Display each book in a table row %] |
491 | [% FOREACH book IN books -%] |
492 | <tr> |
493 | <td>[% book.title %]</td> |
494 | <td>[% book.rating %]</td> |
495 | </tr> |
496 | [% END -%] |
497 | </table> |
498 | |
499 | As indicated by the inline comments above, the C<META title> line uses |
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500 | TT's META feature to provide a title to the "wrapper" that we will |
501 | create later. Meanwhile, the C<FOREACH> loop iterates through each |
502 | C<book> model object and prints the C<title> and C<rating> fields. |
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503 | |
504 | If you are new to TT, the C<[%> and C<%]> tags are used to delimit TT |
505 | code. TT supports a wide variety of directives for "calling" other |
506 | files, looping, conditional logic, etc. In general, TT simplifies the |
507 | usual range of Perl operators down to the single dot (C<.>) operator. |
508 | This applies to operations as diverse as method calls, hash lookups, and |
509 | list index values (see |
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510 | L<http://search.cpan.org/perldoc?Template::Manual::Variables> |
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511 | for details and examples). In addition to the usual C<Template> module |
512 | Pod documentation, you can access the TT manual at |
55beb65d |
513 | L<http://search.cpan.org/perldoc?Template::Manual>. |
3533daff |
514 | |
1390ef0e |
515 | B<TIP:> While you can build all sorts of complex logic into your TT |
516 | templates, you should in general keep the "code" part of your templates |
517 | as simple as possible. If you need more complex logic, create helper |
518 | methods in your model that abstract out a set of code into a single call |
519 | from your TT template. (Note that the same is true of your controller |
520 | logic as well -- complex sections of code in your controllers should |
521 | often be pulled out and placed into your model objects.) |
522 | |
523 | |
524 | =head2 Test Run The Application |
525 | |
526 | To test your work so far, first start the development server: |
527 | |
528 | $ script/myapp_server.pl |
529 | |
530 | Then point your browser to L<http://localhost:3000> and you should |
531 | still get the Catalyst welcome page. Next, change the URL in your |
532 | browser to L<http://localhost:3000/books/list>. If you have |
533 | everything working so far, you should see a web page that displays |
534 | nothing other than our column headers for "Title", "Rating", and |
535 | "Author(s)" -- we will not see any books until we get the database and |
536 | model working below. |
537 | |
538 | If you run into problems getting your application to run correctly, it |
539 | might be helpful to refer to some of the debugging techniques covered in |
540 | the L<Debugging|Catalyst::Manual::Tutorial::Debugging> part of the |
541 | tutorial. |
3533daff |
542 | |
543 | |
544 | =head1 CREATE A SQLITE DATABASE |
545 | |
546 | In this step, we make a text file with the required SQL commands to |
1390ef0e |
547 | create a database table and load some sample data. We will use SQLite, |
548 | a popular database that is lightweight and easy to use. Open |
549 | C<myapp01.sql> in your editor and enter: |
3533daff |
550 | |
551 | -- |
552 | -- Create a very simple database to hold book and author information |
553 | -- |
554 | CREATE TABLE books ( |
555 | id INTEGER PRIMARY KEY, |
556 | title TEXT , |
557 | rating INTEGER |
558 | ); |
559 | -- 'book_authors' is a many-to-many join table between books & authors |
560 | CREATE TABLE book_authors ( |
561 | book_id INTEGER, |
562 | author_id INTEGER, |
563 | PRIMARY KEY (book_id, author_id) |
564 | ); |
565 | CREATE TABLE authors ( |
566 | id INTEGER PRIMARY KEY, |
567 | first_name TEXT, |
568 | last_name TEXT |
569 | ); |
570 | --- |
571 | --- Load some sample data |
572 | --- |
573 | INSERT INTO books VALUES (1, 'CCSP SNRS Exam Certification Guide', 5); |
574 | INSERT INTO books VALUES (2, 'TCP/IP Illustrated, Volume 1', 5); |
575 | INSERT INTO books VALUES (3, 'Internetworking with TCP/IP Vol.1', 4); |
576 | INSERT INTO books VALUES (4, 'Perl Cookbook', 5); |
577 | INSERT INTO books VALUES (5, 'Designing with Web Standards', 5); |
578 | INSERT INTO authors VALUES (1, 'Greg', 'Bastien'); |
579 | INSERT INTO authors VALUES (2, 'Sara', 'Nasseh'); |
580 | INSERT INTO authors VALUES (3, 'Christian', 'Degu'); |
581 | INSERT INTO authors VALUES (4, 'Richard', 'Stevens'); |
582 | INSERT INTO authors VALUES (5, 'Douglas', 'Comer'); |
583 | INSERT INTO authors VALUES (6, 'Tom', 'Christiansen'); |
584 | INSERT INTO authors VALUES (7, 'Nathan', 'Torkington'); |
585 | INSERT INTO authors VALUES (8, 'Jeffrey', 'Zeldman'); |
586 | INSERT INTO book_authors VALUES (1, 1); |
587 | INSERT INTO book_authors VALUES (1, 2); |
588 | INSERT INTO book_authors VALUES (1, 3); |
589 | INSERT INTO book_authors VALUES (2, 4); |
590 | INSERT INTO book_authors VALUES (3, 5); |
591 | INSERT INTO book_authors VALUES (4, 6); |
592 | INSERT INTO book_authors VALUES (4, 7); |
593 | INSERT INTO book_authors VALUES (5, 8); |
594 | |
3533daff |
595 | Then use the following command to build a C<myapp.db> SQLite database: |
596 | |
597 | $ sqlite3 myapp.db < myapp01.sql |
598 | |
599 | If you need to create the database more than once, you probably want to |
600 | issue the C<rm myapp.db> command to delete the database before you use |
1390ef0e |
601 | the C<sqlite3 myapp.db E<lt> myapp01.sql> command. |
3533daff |
602 | |
603 | Once the C<myapp.db> database file has been created and initialized, you |
604 | can use the SQLite command line environment to do a quick dump of the |
605 | database contents: |
606 | |
607 | $ sqlite3 myapp.db |
acbd7bdd |
608 | SQLite version 3.5.9 |
3533daff |
609 | Enter ".help" for instructions |
610 | sqlite> select * from books; |
611 | 1|CCSP SNRS Exam Certification Guide|5 |
612 | 2|TCP/IP Illustrated, Volume 1|5 |
613 | 3|Internetworking with TCP/IP Vol.1|4 |
614 | 4|Perl Cookbook|5 |
615 | 5|Designing with Web Standards|5 |
616 | sqlite> .q |
617 | $ |
618 | |
619 | Or: |
620 | |
621 | $ sqlite3 myapp.db "select * from books" |
622 | 1|CCSP SNRS Exam Certification Guide|5 |
623 | 2|TCP/IP Illustrated, Volume 1|5 |
624 | 3|Internetworking with TCP/IP Vol.1|4 |
625 | 4|Perl Cookbook|5 |
626 | 5|Designing with Web Standards|5 |
627 | |
628 | As with most other SQL tools, if you are using the full "interactive" |
629 | environment you need to terminate your SQL commands with a ";" (it's not |
630 | required if you do a single SQL statement on the command line). Use |
631 | ".q" to exit from SQLite from the SQLite interactive mode and return to |
632 | your OS command prompt. |
633 | |
a6d800ac |
634 | For using other databases, such as PostgreSQL or MySQL, see |
635 | L<Appendix 2|Catalyst::Manual::Tutorial::Appendices>. |
3533daff |
636 | |
acbd7bdd |
637 | |
3533daff |
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 | |
1435672d |
667 | The C<script/myapp_create.pl> command breaks down like this: |
668 | |
669 | =over 4 |
670 | |
671 | =item * |
672 | |
d0496197 |
673 | C<DB> is the name of the model class to be created by the helper in |
1435672d |
674 | C<lib/MyApp/Model>. |
675 | |
676 | =item * |
677 | |
678 | C<DBIC::Schema> is the type of the model to create. |
679 | |
680 | =item * |
681 | |
682 | C<MyApp::Schema> is the name of the DBIC schema file written to |
683 | C<lib/MyApp/Schema.pm>. |
684 | |
685 | =item * |
686 | |
687 | Because we specified C<create=dynamic> to the helper, it use |
1390ef0e |
688 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to |
689 | dynamically load the schema information from the database every time |
1435672d |
690 | the application starts. |
691 | |
692 | =item * |
693 | |
694 | And finally, C<dbi:SQLite:myapp.db> is the standard DBI connect string |
695 | for use with SQLite. |
696 | |
697 | =back |
3533daff |
698 | |
d0496197 |
699 | B<NOTE:> Although the C<create=dynamic> option to the DBIC helper |
19c49089 |
700 | makes for a nifty demonstration, is only really suitable for very |
701 | small applications. After this demonstration, you should almost always |
702 | use the C<create=static> option that we switch to below. |
dc9a0503 |
703 | |
704 | |
1390ef0e |
705 | =head1 ENABLE THE MODEL IN THE CONTROLLER |
706 | |
acbd7bdd |
707 | Open C<lib/MyApp/Controller/Books.pm> and un-comment the model code we |
708 | left disabled earlier so that your version matches the following (un- |
709 | comment the line containing C<[$c-E<gt>model('DB::Books')-E<gt>all]> |
710 | and delete the next 2 lines): |
1390ef0e |
711 | |
712 | =head2 list |
713 | |
714 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
715 | |
716 | =cut |
717 | |
718 | sub list : Local { |
719 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
720 | # 'Context' that's used to 'glue together' the various components |
721 | # that make up the application |
722 | my ($self, $c) = @_; |
723 | |
724 | # Retrieve all of the book records as book model objects and store in the |
725 | # stash where they can be accessed by the TT template |
726 | $c->stash->{books} = [$c->model('DB::Books')->all]; |
727 | |
728 | # Set the TT template to use. You will almost always want to do this |
729 | # in your action methods (action methods respond to user input in |
730 | # your controllers). |
731 | $c->stash->{template} = 'books/list.tt2'; |
732 | } |
733 | |
1435672d |
734 | B<TIP>: You may see the C<$c-E<gt>model('DB::Books')> un-commented |
735 | above written as C<$c-E<gt>model('DB')-E<gt>resultset('Books')>. The |
c93b5eaa |
736 | two are equivalent. Either way, C<$c-E<gt>model> returns a |
737 | L<DBIx::Class::ResultSet|DBIx::Class::ResultSet> which handles queries |
738 | against the database and iterating over the set of results that are |
739 | returned. |
740 | |
741 | We are using the C<-E<gt>all> to fetch all of the books. DBIC |
742 | supports a wide variety of more advanced operations to easily do |
743 | things like filtering and sorting the results. For example, the |
518f3851 |
744 | following could be used to sort the results by descending title: |
c93b5eaa |
745 | |
746 | $c->model('DB::Books')->search({}, {order_by => 'title DESC'}); |
747 | |
748 | Some other examples are provided in |
749 | L<DBIx::Class::Manual::Cookbook/Complex WHERE clauses>, with |
750 | additional information found at L<DBIx::Class::ResultSet/search>, |
751 | L<DBIx::Class::Manual::FAQ/Searching>, |
752 | L<DBIx::Class::Manual::Intro|DBIx::Class::Manual::Intro> |
753 | and L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>. |
1390ef0e |
754 | |
755 | |
756 | =head2 Test Run The Application |
3533daff |
757 | |
1435672d |
758 | First, let's enable an environment variable that causes DBIx::Class to |
acbd7bdd |
759 | dump the SQL statements used to access the database. This is a |
1435672d |
760 | helpful trick when you are trying to debug your database-oriented |
761 | code: |
3533daff |
762 | |
763 | $ export DBIC_TRACE=1 |
764 | |
765 | This assumes you are using BASH as your shell -- adjust accordingly if |
766 | you are using a different shell (for example, under tcsh, use |
767 | C<setenv DBIC_TRACE 1>). |
768 | |
d0496197 |
769 | B<NOTE:> You can also set this in your code using |
3533daff |
770 | C<$class-E<gt>storage-E<gt>debug(1);>. See |
771 | L<DBIx::Class::Manual::Troubleshooting> for details (including options |
772 | to log to file instead of displaying to the Catalyst development server |
773 | log). |
774 | |
1390ef0e |
775 | Then launch the Catalyst development server. The log output should |
776 | display something like: |
3533daff |
777 | |
acbd7bdd |
778 | $ script/myapp_server.pl |
3533daff |
779 | [debug] Debug messages enabled |
1390ef0e |
780 | [debug] Statistics enabled |
3533daff |
781 | [debug] Loaded plugins: |
782 | .----------------------------------------------------------------------------. |
1390ef0e |
783 | | Catalyst::Plugin::ConfigLoader 0.20 | |
784 | | Catalyst::Plugin::StackTrace 0.08 | |
3533daff |
785 | | Catalyst::Plugin::Static::Simple 0.20 | |
786 | '----------------------------------------------------------------------------' |
787 | |
788 | [debug] Loaded dispatcher "Catalyst::Dispatcher" |
789 | [debug] Loaded engine "Catalyst::Engine::HTTP" |
790 | [debug] Found home "/home/me/MyApp" |
45d511e0 |
791 | [debug] Loaded Config "/home/me/MyApp/myapp.conf" |
3533daff |
792 | [debug] Loaded components: |
793 | .-----------------------------------------------------------------+----------. |
794 | | Class | Type | |
795 | +-----------------------------------------------------------------+----------+ |
796 | | MyApp::Controller::Books | instance | |
797 | | MyApp::Controller::Root | instance | |
d0496197 |
798 | | MyApp::Model::DB | instance | |
799 | | MyApp::Model::DB::Authors | class | |
800 | | MyApp::Model::DB::BookAuthors | class | |
801 | | MyApp::Model::DB::Books | class | |
3533daff |
802 | | MyApp::View::TT | instance | |
803 | '-----------------------------------------------------------------+----------' |
804 | |
805 | [debug] Loaded Private actions: |
806 | .----------------------+--------------------------------------+--------------. |
807 | | Private | Class | Method | |
808 | +----------------------+--------------------------------------+--------------+ |
809 | | /default | MyApp::Controller::Root | default | |
810 | | /end | MyApp::Controller::Root | end | |
1390ef0e |
811 | | /index | MyApp::Controller::Root | index | |
3533daff |
812 | | /books/index | MyApp::Controller::Books | index | |
813 | | /books/list | MyApp::Controller::Books | list | |
814 | '----------------------+--------------------------------------+--------------' |
815 | |
816 | [debug] Loaded Path actions: |
817 | .-------------------------------------+--------------------------------------. |
818 | | Path | Private | |
819 | +-------------------------------------+--------------------------------------+ |
1390ef0e |
820 | | / | /default | |
821 | | / | /index | |
822 | | /books | /books/index | |
3533daff |
823 | | /books/list | /books/list | |
824 | '-------------------------------------+--------------------------------------' |
825 | |
acbd7bdd |
826 | [info] MyApp powered by Catalyst 5.71000 |
827 | You can connect to your server at http://debian:3000 |
3533daff |
828 | |
1390ef0e |
829 | B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from |
830 | the 'base' directory of your application, not inside the C<script> |
831 | directory itself or it will not be able to locate the C<myapp.db> |
832 | database file. You can use a fully qualified or a relative path to |
833 | locate the database file, but we did not specify that when we ran the |
3533daff |
834 | model helper earlier. |
835 | |
836 | Some things you should note in the output above: |
837 | |
838 | =over 4 |
839 | |
1390ef0e |
840 | =item * |
3533daff |
841 | |
1390ef0e |
842 | Catalyst::Model::DBIC::Schema dynamically created three model classes, |
843 | one to represent each of the three tables in our database |
d0496197 |
844 | (C<MyApp::Model::DB::Authors>, C<MyApp::Model::DB::BookAuthors>, |
845 | and C<MyApp::Model::DB::Books>). |
3533daff |
846 | |
1390ef0e |
847 | =item * |
3533daff |
848 | |
849 | The "list" action in our Books controller showed up with a path of |
850 | C</books/list>. |
851 | |
852 | =back |
853 | |
854 | Point your browser to L<http://localhost:3000> and you should still get |
855 | the Catalyst welcome page. |
856 | |
857 | Next, to view the book list, change the URL in your browser to |
858 | L<http://localhost:3000/books/list>. You should get a list of the five |
1390ef0e |
859 | books loaded by the C<myapp01.sql> script above without any formatting. |
860 | The rating for each book should appear on each row, but the "Author(s)" |
191dee29 |
861 | column will still be blank (we will fill that in later). |
3533daff |
862 | |
863 | Also notice in the output of the C<script/myapp_server.pl> that DBIC |
864 | used the following SQL to retrieve the data: |
865 | |
866 | SELECT me.id, me.title, me.rating FROM books me |
867 | |
868 | because we enabled DBIC_TRACE. |
869 | |
0c51850e |
870 | You now have the beginnings of a simple but workable web application. |
3533daff |
871 | Continue on to future sections and we will develop the application |
872 | more fully. |
873 | |
874 | |
1390ef0e |
875 | =head1 CREATE A WRAPPER FOR THE VIEW |
876 | |
acbd7bdd |
877 | When using TT, you can (and should) create a wrapper that will |
1390ef0e |
878 | literally wrap content around each of your templates. This is |
879 | certainly useful as you have one main source for changing things that |
880 | will appear across your entire site/application instead of having to |
881 | edit many individual files. |
882 | |
883 | |
884 | =head2 Configure TT.pm For The Wrapper |
885 | |
886 | In order to create a wrapper, you must first edit your TT view and |
887 | tell it where to find your wrapper file. Your TT view is located in |
888 | C<lib/MyApp/View/TT.pm>. |
889 | |
890 | Edit C<lib/MyApp/View/TT.pm> and change it to match the following: |
891 | |
892 | __PACKAGE__->config( |
893 | # Change default TT extension |
894 | TEMPLATE_EXTENSION => '.tt2', |
895 | # Set the location for TT files |
896 | INCLUDE_PATH => [ |
c2dfb562 |
897 | MyApp->path_to( 'root', 'src' ), |
1390ef0e |
898 | ], |
899 | # Set to 1 for detailed timer stats in your HTML as comments |
900 | TIMER => 0, |
901 | # This is your wrapper template located in the 'root/src' |
902 | WRAPPER => 'wrapper.tt2', |
903 | ); |
904 | |
905 | |
906 | =head2 Create the Wrapper Template File and Stylesheet |
907 | |
908 | Next you need to set up your wrapper template. Basically, you'll want |
909 | to take the overall layout of your site and put it into this file. |
910 | For the tutorial, open C<root/src/wrapper.tt2> and input the following: |
911 | |
912 | <?xml version="1.0" encoding="UTF-8"?> |
913 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> |
914 | <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> |
915 | <head> |
916 | <title>[% template.title or "My Catalyst App!" %]</title> |
917 | <link rel="stylesheet" href="[% c.uri_for('/static/css/main.css') %]" /> |
918 | </head> |
919 | |
920 | <body> |
921 | <div id="outer"> |
922 | <div id="header"> |
923 | [%# Your logo could go here -%] |
924 | <img src="[% c.uri_for('/static/images/btn_88x31_powered.png') %]" /> |
925 | [%# Insert the page title -%] |
926 | <h1>[% template.title or site.title %]</h1> |
927 | </div> |
928 | |
929 | <div id="bodyblock"> |
930 | <div id="menu"> |
931 | Navigation: |
932 | <ul> |
933 | <li><a href="[% c.uri_for('/books/list') %]">Home</a></li> |
934 | <li><a href="[% c.uri_for('/') %]" title="Catalyst Welcome Page">Welcome</a></li> |
1390ef0e |
935 | </ul> |
936 | </div><!-- end menu --> |
937 | |
938 | <div id="content"> |
939 | [%# Status and error messages %] |
940 | <span class="message">[% status_msg %]</span> |
941 | <span class="error">[% error_msg %]</span> |
942 | [%# This is where TT will stick all of your template's contents. -%] |
943 | [% content %] |
944 | </div><!-- end content --> |
945 | </div><!-- end bodyblock --> |
946 | |
947 | <div id="footer">Copyright (c) your name goes here</div> |
c2dfb562 |
948 | </div><!-- end outer --> |
1390ef0e |
949 | |
950 | </body> |
951 | </html> |
952 | |
953 | Notice the status and error message sections in the code above: |
954 | |
955 | <span class="status">[% status_msg %]</span> |
956 | <span class="error">[% error_msg %]</span> |
957 | |
958 | If we set either message in the Catalyst stash (e.g., |
959 | C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it |
960 | will be displayed whenever any view used by that request is rendered. |
961 | The C<message> and C<error> CSS styles can be customized to suit your |
962 | needs in the C<root/static/css/main.css> file we create below. |
963 | |
964 | B<Notes:> |
965 | |
966 | =over 4 |
967 | |
968 | =item * |
969 | |
970 | The Catalyst stash only lasts for a single HTTP request. If |
971 | you need to retain information across requests you can use |
972 | L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use |
973 | Catalyst sessions in the Authentication part of the tutorial). |
974 | |
975 | =item * |
976 | |
977 | Although it is beyond the scope of this tutorial, you may wish to use |
978 | a JavaScript or AJAX tool such as jQuery (L<http://www.jquery.com>) or |
979 | Dojo (L<http://www.dojotoolkit.org>). |
980 | |
981 | =back |
982 | |
983 | |
984 | =head3 Create A Basic Stylesheet |
985 | |
986 | First create a central location for stylesheets under the static |
987 | directory: |
988 | |
989 | $ mkdir root/static/css |
990 | |
991 | Then open the file C<root/static/css/main.css> (the file referenced in |
992 | the stylesheet href link of our wrapper above) and add the following |
993 | content: |
994 | |
995 | #header { |
996 | text-align: center; |
997 | } |
998 | #header h1 { |
999 | margin: 0; |
1000 | } |
1001 | #header img { |
1002 | float: right; |
1003 | } |
1004 | #footer { |
1005 | text-align: center; |
1006 | font-style: italic; |
1007 | padding-top: 20px; |
1008 | } |
1009 | #menu { |
1010 | font-weight: bold; |
1011 | background-color: #ddd; |
1012 | } |
1013 | #menu ul { |
1014 | list-style: none; |
1015 | float: left; |
1016 | margin: 0; |
1017 | padding: 0 0 50% 5px; |
1018 | font-weight: normal; |
1019 | background-color: #ddd; |
1020 | width: 100px; |
1021 | } |
1022 | #content { |
1023 | margin-left: 120px; |
1024 | } |
1025 | .message { |
1026 | color: #390; |
1027 | } |
1028 | .error { |
1029 | color: #f00; |
1030 | } |
1031 | |
1032 | You may wish to check out a "CSS Framework" like Emastic |
1033 | (L<http://code.google.com/p/emastic/>) as a way to quickly |
1034 | provide lots of high-quality CSS functionality. |
1035 | |
1036 | |
1037 | =head2 Test Run The Application |
1038 | |
1039 | Restart the development server and hit "Reload" in your web browser |
1040 | and you should now see a formatted version of our basic book list. |
1041 | Although our wrapper and stylesheet are obviously very simple, you |
1042 | should see how it allows us to control the overall look of an entire |
1043 | website from two central files. To add new pages to the site, just |
1044 | provide a template that fills in the C<content> section of our wrapper |
1045 | template -- the wrapper will provide the overall feel of the page. |
1046 | |
1047 | |
3533daff |
1048 | =head1 A STATIC DATABASE MODEL WITH C<DBIx::Class> |
1049 | |
1050 | =head2 Create Static DBIC Schema Files |
1051 | |
1390ef0e |
1052 | Unlike the previous DBIC section where we had C<create=dynamic> |
1053 | automatically discover the structure of the database every time the |
1054 | application started, here we will use static schema files for more |
1055 | control. This is typical of most "real world" applications. |
3533daff |
1056 | |
1390ef0e |
1057 | One option would be to manually create a separate schema file for each |
1058 | table in the database, however, lets use the same |
1059 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> used |
1060 | earlier with C<create=dynamic> to build the static files for us. |
9ad715b3 |
1061 | First, lets remove the schema file created earlier: |
3533daff |
1062 | |
1390ef0e |
1063 | $ rm lib/MyApp/Schema.pm |
3533daff |
1064 | |
1065 | Now regenerate the schema using the C<create=static> option: |
1066 | |
d0496197 |
1067 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema create=static dbi:SQLite:myapp.db |
acbd7bdd |
1068 | exists "/home/me/MyApp/script/../lib/MyApp/Model" |
1069 | exists "/home/me/MyApp/script/../t" |
1070 | Dumping manual schema for MyApp::Schema to directory /home/me/MyApp/script/../lib ... |
3533daff |
1071 | Schema dump completed. |
acbd7bdd |
1072 | exists "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm" |
3533daff |
1073 | |
1390ef0e |
1074 | We could have also deleted C<lib/MyApp/Model/DB.pm>, but it would |
3533daff |
1075 | have regenerated the same file (note the C<exists> in the output above). |
d0496197 |
1076 | If you take a look at C<lib/MyApp/Model/DB.pm>, it simply contains |
1077 | a reference to the actual schema file in C<lib/MyApp/Schema.pm> |
3533daff |
1078 | along with the database connect string. |
1079 | |
1390ef0e |
1080 | If you look in the C<lib/MyApp/Schema.pm> file, you will find that it |
1081 | is no longer using |
1082 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> as its base |
1083 | class (L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> is |
1084 | only being used by the helper to load the schema once and then create |
1085 | the static files for us) and C<Schema.pm> only contains a call to the |
acbd7bdd |
1086 | C<load_classes> method. You will also find that C<lib/MyApp> contains |
1087 | a C<Schema> subdirectory, with files inside this directory named |
1088 | according to each of the tables in our simple database (C<Authors.pm>, |
1089 | C<BookAuthors.pm>, and C<Books.pm>). These three files are called |
1090 | "Result Classes" in DBIC nomenclature. Although the Result Class files |
1091 | are named after tables in our database, the classes correspond to the |
1092 | I<row-level data> that is returned by DBIC (more on this later, |
1093 | especially in |
1094 | L<Catalyst::Manual::Tutorial::BasicCRUD/EXPLORING THE POWER OF DBIC>. |
1095 | |
1096 | The idea with the Result Source files created under |
1097 | C<lib/MyApp/Schema> by the C<create=static> option is to only edit the |
1098 | files below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> warning. |
1099 | If you place all of your changes below that point in the file, you can |
1100 | regenerate the automatically created information at the top of each |
1101 | file should your database structure get updated. |
3533daff |
1102 | |
feb4555a |
1103 | Also note the "flow" of the model information across the various files |
1104 | and directories. Catalyst will initially load the model from |
1105 | C<lib/MyApp/Model/DB.pm>. This file contains a reference to |
1106 | C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, the |
1107 | call to C<load_classes> in C<Schema.pm> will load each of the "result |
1108 | class" files from the C<lib/MyApp/Schema> subdirectory. The end |
1109 | result is that Catalyst will dynamically create three table-specific |
1110 | Catalyst models every time the application starts (you can see these |
1111 | three model files listed in the debug output generated when you launch |
1112 | the application). |
1113 | |
1114 | B<NOTE:> The version of |
1115 | L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> in |
acbd7bdd |
1116 | Debian 5 uses the older DBIC C<load_classes> vs. the newer |
feb4555a |
1117 | C<load_namspaces> technique. For new applications, please try to use |
1118 | C<load_namespaces> since it more easily supports a very useful DBIC |
1cde0fd6 |
1119 | technique called "ResultSet Classes." We will migrate to |
1120 | C<load_namespaces> in Part 4 (BasicCRUD) of this tutorial. |
3533daff |
1121 | |
1122 | |
1123 | =head2 Updating the Generated DBIC Schema Files |
1124 | |
acbd7bdd |
1125 | Let's manually add some relationship information to the auto-generated |
1126 | Result Class files. (Note: if you are using a database other than |
1127 | SQLite, such as PostgreSQL, then the relationship could have been |
1128 | automatically placed in the Result Class files. If so, you can skip |
1129 | this step.) First edit C<lib/MyApp/Schema/Books.pm> and add the |
1130 | following text below the C<# You can replace this text...> comment: |
3533daff |
1131 | |
1132 | # |
1133 | # Set relationships: |
1390ef0e |
1134 | # |
3533daff |
1135 | |
1136 | # has_many(): |
1137 | # args: |
1138 | # 1) Name of relationship, DBIC will create accessor with this name |
1139 | # 2) Name of the model class referenced by this relationship |
1435672d |
1140 | # 3) Column name in *foreign* table (aka, foreign key in peer table) |
d0496197 |
1141 | __PACKAGE__->has_many(book_authors => 'MyApp::Schema::BookAuthors', 'book_id'); |
3533daff |
1142 | |
1143 | # many_to_many(): |
1144 | # args: |
1145 | # 1) Name of relationship, DBIC will create accessor with this name |
1390ef0e |
1146 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
1147 | # 3) Name of belongs_to() relationship in model class of has_many() above |
3533daff |
1148 | # You must already have the has_many() defined to use a many_to_many(). |
1149 | __PACKAGE__->many_to_many(authors => 'book_authors', 'author'); |
1150 | |
1151 | |
1152 | B<Note:> Be careful to put this code I<above> the C<1;> at the end of the |
1153 | file. As with any Perl package, we need to end the last line with |
1154 | a statement that evaluates to C<true>. This is customarily done with |
1155 | C<1;> on a line by itself. |
1156 | |
acbd7bdd |
1157 | C<Important Note:> Although this tutorial uses plural names for both |
1158 | the names of the SQL tables and therefore the Result Classes (after |
1159 | all, C<Schema::Loader> automatically named the Result Classes from the |
1160 | names of the SQL tables it found), DBIC users prefer singular names |
1161 | for these items. B<Please try to use singular table and DBIC |
1162 | model/Result Class names in your applications.> This tutorial will |
1163 | migrate to singular names as soon as possible (patches welcomed). |
1164 | B<Note that while singular is preferred for the DBIC model, plural is |
1165 | perfectly acceptable for the names of the controller classes.> After |
1166 | all, the C<Books.pm> controller operates on multiple books. |
1167 | |
1390ef0e |
1168 | This code defines both a C<has_many> and a C<many_to_many> relationship. |
1169 | The C<many_to_many> relationship is optional, but it makes it easier to |
1170 | map a book to its collection of authors. Without it, we would have to |
1171 | "walk" though the C<book_authors> table as in |
1172 | C<$book-E<gt>book_authors-E<gt>first-E<gt>author-E<gt>last_name> |
1173 | (we will see examples on how to use DBIC objects in your code soon, |
1174 | but note that because C<$book-E<gt>book_authors> can return multiple |
1175 | authors, we have to use C<first> to display a single author). |
1176 | C<many_to_many> allows us to use the shorter |
1177 | C<$book-E<gt>authors-E<gt>first-E<gt>last_name>. |
1178 | Note that you cannot define a C<many_to_many> relationship without |
1179 | also having the C<has_many> relationship in place. |
3533daff |
1180 | |
d0496197 |
1181 | Then edit C<lib/MyApp/Schema/Authors.pm> and add relationship |
3533daff |
1182 | information as follows (again, be careful to put in above the C<1;> but |
1183 | below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> comment): |
1184 | |
1185 | # |
1186 | # Set relationships: |
1187 | # |
1188 | |
1189 | # has_many(): |
1190 | # args: |
1191 | # 1) Name of relationship, DBIC will create accessor with this name |
1192 | # 2) Name of the model class referenced by this relationship |
1435672d |
1193 | # 3) Column name in *foreign* table (aka, foreign key in peer table) |
d0496197 |
1194 | __PACKAGE__->has_many(book_author => 'MyApp::Schema::BookAuthors', 'author_id'); |
3533daff |
1195 | |
1196 | # many_to_many(): |
1197 | # args: |
1198 | # 1) Name of relationship, DBIC will create accessor with this name |
1199 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
1390ef0e |
1200 | # 3) Name of belongs_to() relationship in model class of has_many() above |
3533daff |
1201 | # You must already have the has_many() defined to use a many_to_many(). |
1202 | __PACKAGE__->many_to_many(books => 'book_author', 'book'); |
1203 | |
1390ef0e |
1204 | Finally, do the same for the "join table," |
d0496197 |
1205 | C<lib/MyApp/Schema/BookAuthors.pm>: |
3533daff |
1206 | |
1207 | # |
1208 | # Set relationships: |
1209 | # |
1210 | |
1211 | # belongs_to(): |
1212 | # args: |
1213 | # 1) Name of relationship, DBIC will create accessor with this name |
1214 | # 2) Name of the model class referenced by this relationship |
1215 | # 3) Column name in *this* table |
d0496197 |
1216 | __PACKAGE__->belongs_to(book => 'MyApp::Schema::Books', 'book_id'); |
3533daff |
1217 | |
1218 | # belongs_to(): |
1219 | # args: |
1220 | # 1) Name of relationship, DBIC will create accessor with this name |
1221 | # 2) Name of the model class referenced by this relationship |
1222 | # 3) Column name in *this* table |
d0496197 |
1223 | __PACKAGE__->belongs_to(author => 'MyApp::Schema::Authors', 'author_id'); |
3533daff |
1224 | |
1225 | |
1390ef0e |
1226 | =head2 Run The Application |
3533daff |
1227 | |
1228 | Run the Catalyst "demo server" script with the C<DBIC_TRACE> option |
1229 | (it might still be enabled from earlier in the tutorial, but here |
1230 | is an alternate way to specify the option just in case): |
1231 | |
1232 | $ DBIC_TRACE=1 script/myapp_server.pl |
1233 | |
1390ef0e |
1234 | Make sure that the application loads correctly and that you see the |
1235 | three dynamically created model class (one for each of the |
3533daff |
1236 | table-specific schema classes we created). |
1237 | |
acbd7bdd |
1238 | Then hit the URL L<http://localhost:3000/books/list> with your browser |
1239 | and be sure that the book list is displayed via the relationships |
1240 | established above. You can leave the development server running for |
1241 | the next step if you wish. |
3533daff |
1242 | |
c2dfb562 |
1243 | B<Note:> You will not see the authors yet because the view does not yet |
1244 | use the new relations. Read on to the next section where we update the |
1245 | template to do that. |
3533daff |
1246 | |
1247 | |
1248 | =head1 UPDATING THE VIEW |
1249 | |
acbd7bdd |
1250 | Let's add a new column to our book list page that takes advantage of |
1251 | the relationship information we manually added to our schema files in |
1252 | the previous section. Edit C<root/src/books/list.tt2> add add the |
1253 | following code below the existing table cell that contains |
1254 | C<book.rating> (IOW, add a new table cell below the existing two |
1255 | C<E<lt>tdE<gt>> tags but above the closing C<E<lt>/trE<gt>> and |
1256 | C<E<lt>/tableE<gt>> tags): |
3533daff |
1257 | |
acbd7bdd |
1258 | ... |
3533daff |
1259 | <td> |
1260 | [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%] |
1261 | [% # loop in 'side effect notation' to load just the last names of the -%] |
a0c5188a |
1262 | [% # authors into the list. Note that the 'push' TT vmethod does not print -%] |
3533daff |
1263 | [% # a value, so nothing will be printed here. But, if you have something -%] |
1264 | [% # in TT that does return a method and you don't want it printed, you -%] |
1265 | [% # can: 1) assign it to a bogus value, or 2) use the CALL keyword to -%] |
1266 | [% # call it and discard the return value. -%] |
1267 | [% tt_authors = [ ]; |
1268 | tt_authors.push(author.last_name) FOREACH author = book.authors %] |
1269 | [% # Now use a TT 'virtual method' to display the author count in parens -%] |
1270 | [% # Note the use of the TT filter "| html" to escape dangerous characters -%] |
1271 | ([% tt_authors.size | html %]) |
1272 | [% # Use another TT vmethod to join & print the names & comma separators -%] |
1273 | [% tt_authors.join(', ') | html %] |
1274 | </td> |
acbd7bdd |
1275 | ... |
3533daff |
1276 | |
1390ef0e |
1277 | Then hit "Reload" in your browser (note that you don't need to reload |
3533daff |
1278 | the development server or use the C<-r> option when updating TT |
1390ef0e |
1279 | templates) and you should now see the number of authors each book has |
1280 | along with a comma-separated list of the authors' last names. (If you |
1281 | didn't leave the development server running from the previous step, |
1282 | you will obviously need to start it before you can refresh your |
1283 | browser window.) |
1284 | |
1285 | If you are still running the development server with C<DBIC_TRACE> |
1286 | enabled, you should also now see five more C<SELECT> statements in the |
1287 | debug output (one for each book as the authors are being retrieved by |
acbd7bdd |
1288 | DBIC): |
3533daff |
1289 | |
c2dfb562 |
1290 | SELECT me.id, me.title, me.rating FROM books me: |
acbd7bdd |
1291 | SELECT author.id, author.first_name, author.last_name FROM book_authors me |
1292 | JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '1' |
1293 | SELECT author.id, author.first_name, author.last_name FROM book_authors me |
1294 | JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '2' |
1295 | SELECT author.id, author.first_name, author.last_name FROM book_authors me |
1296 | JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '3' |
1297 | SELECT author.id, author.first_name, author.last_name FROM book_authors me |
1298 | JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '4' |
1299 | SELECT author.id, author.first_name, author.last_name FROM book_authors me |
1300 | JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '5' |
c2dfb562 |
1301 | |
1302 | Also note in C<root/src/books/list.tt2> that we are using "| html", a |
1303 | type of TT filter, to escape characters such as E<lt> and E<gt> to < |
1304 | and > and avoid various types of dangerous hacks against your |
1305 | application. In a real application, you would probably want to put |
1306 | "| html" at the end of every field where a user has control over the |
1307 | information that can appear in that field (and can therefore inject |
1308 | markup or code if you don't "neutralize" those fields). In addition to |
1309 | "| html", Template Toolkit has a variety of other useful filters that |
1310 | can found in the documentation for |
1311 | L<Template::Filters|Template::Filters>. |
3533daff |
1312 | |
1313 | |
1390ef0e |
1314 | =head1 RUNNING THE APPLICATION FROM THE COMMAND LINE |
1315 | |
1316 | In some situations, it can be useful to run your application and |
1317 | display a page without using a browser. Catalyst lets you do this |
1318 | using the C<scripts/myapp_test.pl> script. Just supply the URL you |
1319 | wish to display and it will run that request through the normal |
1320 | controller dispatch logic and use the appropriate view to render the |
1321 | output (obviously, complex pages may dump a lot of text to your |
1322 | terminal window). For example, if you type: |
1323 | |
1324 | $ script/myapp_test.pl "/books/list" |
1325 | |
1326 | You should get the same text as if you visited |
1327 | L<http://localhost:3000/books/list> with the normal development server |
1328 | and asked your browser to view the page source. |
3533daff |
1329 | |
1390ef0e |
1330 | |
1331 | =head1 OPTIONAL INFORMATION |
1332 | |
1333 | B<NOTE: The rest of this part of the tutorial is optional. You can |
1334 | skip to Part 4, L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>, |
3533daff |
1335 | if you wish.> |
1336 | |
acbd7bdd |
1337 | |
1390ef0e |
1338 | =head2 Using C<RenderView> for the Default View |
1339 | |
1340 | Once your controller logic has processed the request from a user, it |
1341 | forwards processing to your view in order to generate the appropriate |
3533daff |
1342 | response output. Catalyst uses |
1390ef0e |
1343 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by |
1344 | default to automatically performs this operation. If you look in |
1345 | C<lib/MyApp/Controller/Root.pm>, you should see the empty |
3533daff |
1346 | definition for the C<sub end> method: |
1347 | |
1348 | sub end : ActionClass('RenderView') {} |
1349 | |
1390ef0e |
1350 | The following bullet points provide a quick overview of the |
3533daff |
1351 | C<RenderView> process: |
1352 | |
1353 | =over 4 |
1354 | |
1355 | =item * |
1356 | |
1357 | C<Root.pm> is designed to hold application-wide logic. |
1358 | |
1359 | =item * |
1360 | |
1390ef0e |
1361 | At the end of a given user request, Catalyst will call the most specific |
1362 | C<end> method that's appropriate. For example, if the controller for a |
1363 | request has an C<end> method defined, it will be called. However, if |
1364 | the controller does not define a controller-specific C<end> method, the |
3533daff |
1365 | "global" C<end> method in C<Root.pm> will be called. |
1366 | |
1367 | =item * |
1368 | |
1369 | Because the definition includes an C<ActionClass> attribute, the |
1370 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic |
1371 | will be executed B<after> any code inside the definition of C<sub end> |
1372 | is run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions> |
1373 | for more information on C<ActionClass>. |
1374 | |
1375 | =item * |
1376 | |
1390ef0e |
1377 | Because C<sub end> is empty, this effectively just runs the default |
1378 | logic in C<RenderView>. However, you can easily extend the |
1379 | C<RenderView> logic by adding your own code inside the empty method body |
1380 | (C<{}>) created by the Catalyst Helpers when we first ran the |
1381 | C<catalyst.pl> to initialize our application. See |
1382 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more |
3533daff |
1383 | detailed information on how to extended C<RenderView> in C<sub end>. |
1384 | |
1385 | =back |
1386 | |
1387 | |
1388 | =head2 Using The Default Template Name |
1389 | |
1390ef0e |
1390 | By default, C<Catalyst::View::TT> will look for a template that uses the |
1391 | same name as your controller action, allowing you to save the step of |
1392 | manually specifying the template name in each action. For example, this |
1393 | would allow us to remove the |
1394 | C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our |
1395 | C<list> action in the Books controller. Open |
3533daff |
1396 | C<lib/MyApp/Controller/Books.pm> in your editor and comment out this line |
1397 | to match the following (only the C<$c-E<gt>stash-E<gt>{template}> line |
1398 | has changed): |
1399 | |
1400 | =head2 list |
1401 | |
1402 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
1403 | |
1404 | =cut |
1405 | |
1406 | sub list : Local { |
1407 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
1408 | # 'Context' that's used to 'glue together' the various components |
1409 | # that make up the application |
1410 | my ($self, $c) = @_; |
1411 | |
1412 | # Retrieve all of the book records as book model objects and store in the |
1413 | # stash where they can be accessed by the TT template |
d0496197 |
1414 | $c->stash->{books} = [$c->model('DB::Books')->all]; |
3533daff |
1415 | |
1416 | # Set the TT template to use. You will almost always want to do this |
1417 | # in your action methods (actions methods respond to user input in |
1418 | # your controllers). |
1419 | #$c->stash->{template} = 'books/list.tt2'; |
1420 | } |
1421 | |
3533daff |
1422 | |
1390ef0e |
1423 | You should now be able to restart the development server as per the |
3533daff |
1424 | previous section and access the L<http://localhost:3000/books/list> |
1425 | as before. |
1426 | |
1427 | B<NOTE:> Please note that if you use the default template technique, |
1428 | you will B<not> be able to use either the C<$c-E<gt>forward> or |
1390ef0e |
1429 | the C<$c-E<gt>detach> mechanisms (these are discussed in Part 2 and |
3533daff |
1430 | Part 9 of the Tutorial). |
1431 | |
1432 | |
1433 | =head2 Return To A Manually-Specified Template |
1434 | |
1435 | In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach> |
1436 | later in the tutorial, you should remove the comment from the |
1437 | statement in C<sub list> in C<lib/MyApp/Controller/Books.pm>: |
1438 | |
1439 | $c->stash->{template} = 'books/list.tt2'; |
1440 | |
1390ef0e |
1441 | Then delete the C<TEMPLATE_EXTENSION> line in |
3533daff |
1442 | C<lib/MyApp/View/TT.pm>. |
1443 | |
1390ef0e |
1444 | You should then be able to restart the development server and |
3533daff |
1445 | access L<http://localhost:3000/books/list> in the same manner as |
1446 | with earlier sections. |
1447 | |
1448 | |
1449 | =head1 AUTHOR |
1450 | |
1451 | Kennedy Clark, C<hkclark@gmail.com> |
1452 | |
1453 | Please report any errors, issues or suggestions to the author. The |
1454 | most recent version of the Catalyst Tutorial can be found at |
82ab4bbf |
1455 | L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>. |
3533daff |
1456 | |
45c7830f |
1457 | Copyright 2006-2008, Kennedy Clark, under Creative Commons License |
8482d557 |
1458 | (L<http://creativecommons.org/licenses/by-sa/3.0/us/>). |