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1 | =head1 NAME |
2 | |
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3 | Catalyst::Manual::Tutorial::03_MoreCatalystBasics - Catalyst Tutorial - Chapter 3: More Catalyst Application Development Basics |
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4 | |
5 | |
6 | =head1 OVERVIEW |
7 | |
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8 | This is B<Chapter 3 of 10> for the Catalyst tutorial. |
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9 | |
10 | L<Tutorial Overview|Catalyst::Manual::Tutorial> |
11 | |
12 | =over 4 |
13 | |
14 | =item 1 |
15 | |
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16 | L<Introduction|Catalyst::Manual::Tutorial::01_Intro> |
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17 | |
18 | =item 2 |
19 | |
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20 | L<Catalyst Basics|Catalyst::Manual::Tutorial::02_CatalystBasics> |
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21 | |
22 | =item 3 |
23 | |
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24 | B<03_More Catalyst Basics> |
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25 | |
26 | =item 4 |
27 | |
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28 | L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD> |
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29 | |
30 | =item 5 |
31 | |
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32 | L<Authentication|Catalyst::Manual::Tutorial::05_Authentication> |
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33 | |
34 | =item 6 |
35 | |
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36 | L<Authorization|Catalyst::Manual::Tutorial::06_Authorization> |
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37 | |
38 | =item 7 |
39 | |
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40 | L<Debugging|Catalyst::Manual::Tutorial::07_Debugging> |
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41 | |
42 | =item 8 |
43 | |
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44 | L<Testing|Catalyst::Manual::Tutorial::08_Testing> |
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45 | |
46 | =item 9 |
47 | |
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48 | L<Advanced CRUD|Catalyst::Manual::Tutorial::09_AdvancedCRUD> |
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49 | |
50 | =item 10 |
51 | |
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52 | L<Appendices|Catalyst::Manual::Tutorial::10_Appendices> |
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53 | |
54 | =back |
55 | |
56 | |
57 | =head1 DESCRIPTION |
58 | |
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59 | This chapter of the tutorial builds on the work done in Chapter 2 to |
60 | explore some features that are more typical of "real world" web |
61 | applications. From this chapter of the tutorial onward, we will be |
62 | building a simple book database application. Although the application |
63 | will be too limited to be of use to anyone, it should provide a basic |
64 | environment where we can explore a variety of features used in virtually |
65 | all web applications. |
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66 | |
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67 | You can check out the source code for this example from the Catalyst |
68 | Subversion repository as per the instructions in |
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69 | L<Catalyst::Manual::Tutorial::01_Intro|Catalyst::Manual::Tutorial::01_Intro>. |
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70 | |
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71 | Please take a look at |
72 | L<Catalyst::Manual::Tutorial::01_Intro/CATALYST INSTALLATION> before |
73 | doing the rest of this tutorial. Although the tutorial should work |
74 | correctly under most any recent version of Perl running on any operating |
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75 | system, the tutorial has been written using Debian 6 and tested to be |
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76 | sure it runs correctly in this environment. |
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77 | |
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78 | |
79 | =head1 CREATE A NEW APPLICATION |
80 | |
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81 | The remainder of the tutorial will build an application called C<MyApp>. |
82 | First use the Catalyst C<catalyst.pl> script to initialize the framework |
83 | for the C<MyApp> application (make sure you aren't still inside the |
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84 | directory of the C<Hello> application from the previous chapter of the |
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85 | tutorial or in a directory that already has a "MyApp" subdirectory): |
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86 | |
87 | $ catalyst.pl MyApp |
88 | created "MyApp" |
89 | created "MyApp/script" |
90 | created "MyApp/lib" |
91 | created "MyApp/root" |
92 | ... |
93 | created "MyApp/script/myapp_create.pl" |
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94 | Change to application directory and Run "perl Makefile.PL" to make sure your install is complete |
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95 | $ cd MyApp |
96 | |
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97 | This creates a similar skeletal structure to what we saw in Chapter 2 of |
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98 | the tutorial, except with C<MyApp> and C<myapp> substituted for C<Hello> |
99 | and C<hello>. (As noted in Chapter 2, omit the ".pl" from the command |
100 | if you are using Strawberry Perl.) |
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101 | |
102 | |
103 | =head1 EDIT THE LIST OF CATALYST PLUGINS |
104 | |
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105 | One of the greatest benefits of Catalyst is that it has such a large |
106 | library of bases classes and plugins available that you can use easily |
107 | add functionality to your application. Plugins are used to seamlessly |
108 | integrate existing Perl modules into the overall Catalyst framework. In |
109 | general, they do this by adding additional methods to the C<context> |
110 | object (generally written as C<$c>) that Catalyst passes to every |
111 | component throughout the framework. |
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112 | |
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113 | |
114 | By default, Catalyst enables three plugins/flags: |
115 | |
116 | =over 4 |
117 | |
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118 | =item * |
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119 | |
120 | C<-Debug> Flag |
121 | |
122 | Enables the Catalyst debug output you saw when we started the |
123 | C<script/myapp_server.pl> development server earlier. You can remove |
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124 | this item when you place your application into production. |
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125 | |
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126 | To be technically correct, it turns out that C<-Debug> is not a plugin, |
127 | but a I<flag>. Although most of the items specified on the |
128 | C<__PACKAGE__-E<gt>setup> line of your application class will be |
129 | plugins, Catalyst supports a limited number of flag options (of these, |
130 | C<-Debug> is the most common). See the documentation for C<Catalyst.pm> |
131 | to get details on other flags (currently C<-Engine>, C<-Home>, and |
132 | C<-Log>). |
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133 | |
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134 | If you prefer, there are several other ways to enable debug output: |
135 | |
136 | =over 4 |
137 | |
138 | =item * |
139 | |
140 | Use the C<$c-E<gt>debug> method |
141 | |
142 | =item * |
143 | |
144 | The C<-d> option to C<script/myapp_server.pl> |
145 | |
146 | =item * |
147 | |
148 | The C<CATALYST_DEBUG=1> environment variable (or set it to |
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149 | zero to temporarily disable debug output). |
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150 | |
151 | =back |
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152 | |
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153 | B<TIP>: Depending on your needs, it can be helpful to permanently remove |
154 | C<-Debug> from C<lib/MyApp.pm> and then use the C<-d> option to |
155 | C<script/myapp_server.pl> to re-enable it just for the development |
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156 | server. We will not be using that approach in the tutorial, but feel |
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157 | free to make use of it in your own projects. |
158 | |
159 | =item * |
160 | |
161 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> |
162 | |
163 | C<ConfigLoader> provides an automatic way to load configurable |
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164 | parameters for your application from a central |
165 | L<Config::General|Config::General> file (versus having the values |
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166 | hard-coded inside your Perl modules). Config::General uses syntax very |
167 | similar to Apache configuration files. We will see how to use this |
168 | feature of Catalyst during the authentication and authorization sections |
169 | (Chapter 5 and Chapter 6). |
170 | |
171 | B<IMPORTANT NOTE:> If you are using a version of |
172 | L<Catalyst::Devel|Catalyst::Devel> prior to version 1.06, be aware that |
173 | Catalyst changed the default format from YAML to the more |
174 | straightforward C<Config::General> style. This tutorial uses the newer |
175 | C<myapp.conf> file for C<Config::General>. However, Catalyst supports |
176 | both formats and will automatically use either C<myapp.conf> or |
177 | C<myapp.yml> (or any other format supported by |
178 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> and |
179 | L<Config::Any|Config::Any>). If you are using a version of |
180 | Catalyst::Devel prior to 1.06, you can convert to the newer format by |
181 | simply creating the C<myapp.conf> file manually and deleting |
182 | C<myapp.yml>. The default contents of the C<myapp.conf> you create |
183 | should only consist of one line: |
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184 | |
185 | name MyApp |
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186 | |
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187 | B<TIP>: This script can be useful for converting between configuration |
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188 | formats: |
189 | |
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190 | perl -Ilib -e 'use MyApp; use Config::General; |
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191 | Config::General->new->save_file("myapp.conf", MyApp->config);' |
192 | |
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193 | =item * |
194 | |
195 | L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple> |
196 | |
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197 | C<Static::Simple> provides an easy way to serve static content, such as |
198 | images and CSS files, from the development server. |
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199 | |
200 | =back |
201 | |
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202 | For our application, we want to add one new plugin into the mix. To do |
203 | this, edit C<lib/MyApp.pm> (this file is generally referred to as your |
204 | I<application class>) and delete the lines with: |
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205 | |
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206 | use Catalyst qw/ |
207 | -Debug |
208 | ConfigLoader |
209 | Static::Simple |
210 | /; |
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211 | |
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212 | Then replace it with: |
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213 | |
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214 | # Load plugins |
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215 | use Catalyst qw/ |
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216 | -Debug |
217 | ConfigLoader |
218 | Static::Simple |
219 | |
220 | StackTrace |
221 | /; |
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222 | |
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223 | B<Note:> Recent versions of C<Catalyst::Devel> have used a variety of |
224 | techniques to load these plugins/flags. For example, you might see the |
225 | following: |
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226 | |
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227 | __PACKAGE__->setup(qw/-Debug ConfigLoader Static::Simple/); |
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228 | |
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229 | Don't let these variations confuse you -- they all accomplish the same |
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230 | result. |
231 | |
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232 | This tells Catalyst to start using one additional plugin, |
233 | L<Catalyst::Plugin::StackTrace>, to add a stack trace to the standard |
234 | Catalyst "debug screen" (the screen Catalyst sends to your browser when |
235 | an error occurs). Be aware that |
236 | L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your |
237 | browser, not in the console window from which you're running your |
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238 | application, which is where logging output usually goes. |
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239 | |
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240 | Make sure when adding new plugins you also include them as a new |
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241 | dependency within the Makefile.PL file. For example, after adding the |
242 | StackTrace plugin the Makefile.PL should include the following line: |
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243 | |
244 | requires 'Catalyst::Plugin::StackTrace'; |
245 | |
246 | |
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247 | B<Notes:> |
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248 | |
249 | =over 4 |
250 | |
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251 | =item * |
252 | |
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253 | C<__PACKAGE__> is just a shorthand way of referencing the name of the |
254 | package where it is used. Therefore, in C<MyApp.pm>, C<__PACKAGE__> is |
255 | equivalent to C<MyApp>. |
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256 | |
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257 | =item * |
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258 | |
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259 | You will want to disable L<StackTrace|Catalyst::Plugin::StackTrace> |
260 | before you put your application into production, but it can be helpful |
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261 | during development. |
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262 | |
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263 | =item * |
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264 | |
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265 | When specifying plugins, you can omit C<Catalyst::Plugin::> from the |
266 | name. Additionally, you can spread the plugin names across multiple |
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267 | lines as shown here or place them all on one line. |
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268 | |
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269 | =back |
270 | |
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271 | |
272 | =head1 CREATE A CATALYST CONTROLLER |
273 | |
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274 | As discussed earlier, controllers are where you write methods that |
275 | interact with user input. Typically, controller methods respond to |
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276 | C<GET> and C<POST> requests from the user's web browser. |
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277 | |
278 | Use the Catalyst C<create> script to add a controller for book-related |
279 | actions: |
280 | |
281 | $ script/myapp_create.pl controller Books |
282 | exists "/home/me/MyApp/script/../lib/MyApp/Controller" |
283 | exists "/home/me/MyApp/script/../t" |
284 | created "/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm" |
285 | created "/home/me/MyApp/script/../t/controller_Books.t" |
286 | |
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287 | Then edit C<lib/MyApp/Controller/Books.pm> (as discussed in Chapter 2 of |
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288 | the Tutorial, Catalyst has a separate directory under C<lib/MyApp> for |
289 | each of the three parts of MVC: C<Model>, C<View>, and C<Controller>) |
290 | and add the following method to the controller: |
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291 | |
292 | =head2 list |
293 | |
294 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
295 | |
296 | =cut |
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297 | |
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298 | sub list :Local { |
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299 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
300 | # 'Context' that's used to 'glue together' the various components |
301 | # that make up the application |
302 | my ($self, $c) = @_; |
303 | |
304 | # Retrieve all of the book records as book model objects and store in the |
305 | # stash where they can be accessed by the TT template |
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306 | # $c->stash(books => [$c->model('DB::Book')->all]); |
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307 | # But, for now, use this code until we create the model later |
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308 | $c->stash(books => ''); |
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309 | |
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310 | # Set the TT template to use. You will almost always want to do this |
311 | # in your action methods (action methods respond to user input in |
312 | # your controllers). |
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313 | $c->stash(template => 'books/list.tt2'); |
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314 | } |
315 | |
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316 | B<TIP>: See Appendix 1 for tips on removing the leading spaces when |
317 | cutting and pasting example code from POD-based documents. |
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318 | |
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319 | Programmers experienced with object-oriented Perl should recognize |
320 | C<$self> as a reference to the object where this method was called. On |
321 | the other hand, C<$c> will be new to many Perl programmers who have not |
322 | used Catalyst before (it's sometimes written as C<$context>). The |
323 | Context object is automatically passed to all Catalyst components. It |
324 | is used to pass information between components and provide access to |
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325 | Catalyst and plugin functionality. |
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326 | |
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327 | Catalyst actions are regular Perl methods, but they make use of |
328 | attributes (the "C<:Local>" next to the "C<sub list>" in the code above) |
329 | to provide additional information to the Catalyst dispatcher logic (note |
330 | that the space between the colon and the attribute name is optional; you |
331 | will see attributes written both ways). Most Catalyst Controllers use |
332 | one of five action types: |
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333 | |
334 | =over 4 |
335 | |
336 | =item * |
337 | |
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338 | B<:Private> -- Use C<:Private> for methods that you want to make into an |
339 | action, but you do not want Catalyst to directly expose the method to |
340 | your users. Catalyst will not map C<:Private> methods to a URI. Use |
341 | them for various sorts of "special" methods (the C<begin>, C<auto>, etc. |
342 | discussed below) or for methods you want to be able to C<forward> or |
343 | C<detach> to. (If the method is a plain old "helper method" that you |
344 | don't want to be an action at all, then just define the method without |
345 | any attribute -- you can call it in your code, but the Catalyst |
346 | dispatcher will ignore it.) |
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347 | |
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348 | There are five types of "special" built-in C<:Private> actions: |
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349 | C<begin>, C<end>, C<default>, C<index>, and C<auto>. |
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350 | |
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351 | =over 4 |
352 | |
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353 | =item * |
354 | |
355 | With C<begin>, C<end>, C<default>, C<index> private actions, only the |
356 | most specific action of each type will be called. For example, if you |
357 | define a C<begin> action in your controller it will I<override> a |
358 | C<begin> action in your application/root controller -- I<only> the |
359 | action in your controller will be called. |
360 | |
361 | =item * |
362 | |
363 | Unlike the other actions where only a single method is called for each |
364 | request, I<every> auto action along the chain of namespaces will be |
365 | called. Each C<auto> action will be called I<from the application/root |
366 | controller down through the most specific class>. |
367 | |
368 | =back |
369 | |
370 | =item * |
371 | |
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372 | B<:Path> -- C<:Path> actions let you map a method to an explicit URI |
373 | path. For example, "C<:Path('list')>" in |
374 | C<lib/MyApp/Controller/Books.pm> would match on the URL |
375 | C<http://localhost:3000/books/list>, but "C<:Path('/list')>" would match |
376 | on C<http://localhost:3000/list> (because of the leading slash). You |
377 | can use C<:Args()> to specify how many arguments an action should |
378 | accept. See L<Catalyst::Manual::Intro/Action_types> for more |
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379 | information and examples. |
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380 | |
381 | =item * |
382 | |
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383 | B<:Local> -- C<:Local> is merely a shorthand for |
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384 | "C<:Path('_name_of_method_')>". For example, these are equivalent: |
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385 | "C<sub create_book :Local {...}>" and "C<sub create_book |
386 | :Path('create_book') {...}>". |
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387 | |
388 | =item * |
389 | |
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390 | B<:Global> -- C<:Global> is merely a shorthand for |
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391 | "C<:Path('/_name_of_method_')>". For example, these are equivalent: |
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392 | "C<sub create_book :Global {...}>" and "C<sub create_book |
393 | :Path('/create_book') {...}>". |
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394 | |
395 | =item * |
396 | |
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397 | B<:Chained> -- Newer Catalyst applications tend to use the Chained |
398 | dispatch form of action types because of its power and flexibility. It |
399 | allows a series of controller methods to be automatically dispatched to |
400 | service a single user request. See |
401 | L<Catalyst::Manual::Tutorial::04_BasicCRUD|Catalyst::Manual::Tutorial::04_BasicCRUD> |
402 | and L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained> |
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403 | for more information on chained actions. |
404 | |
405 | =back |
406 | |
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407 | You should refer to L<Catalyst::Manual::Intro/Action_types> for |
408 | additional information and for coverage of some lesser-used action types |
409 | not discussed here (C<Regex> and C<LocalRegex>). |
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410 | |
411 | |
412 | =head1 CATALYST VIEWS |
413 | |
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414 | As mentioned in Chapter 2 of the tutorial, views are where you render |
415 | output, typically for display in the user's web browser (but also |
416 | possibly using into output-generation systems, such as PDF or JSON). |
417 | The code in C<lib/MyApp/View> selects the I<type> of view to use, with |
418 | the actual rendering template found in the C<root> directory. As with |
419 | virtually every aspect of Catalyst, options abound when it comes to the |
420 | specific view technology you adopt inside your application. However, |
421 | most Catalyst applications use the Template Toolkit, known as TT (for |
422 | more information on TT, see L<http://www.template-toolkit.org>). Other |
423 | somewhat popular view technologies include Mason |
424 | (L<http://www.masonhq.com> and L<http://www.masonbook.com>) and |
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425 | L<HTML::Template> (L<http://html-template.sourceforge.net>). |
426 | |
427 | |
428 | =head2 Create a Catalyst View |
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429 | |
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430 | When using TT for the Catalyst view, the main helper script is |
431 | L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT>. You may also |
432 | come across references to |
433 | L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite>, but |
434 | its use is now deprecated. |
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435 | |
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436 | Enter the following command to enable the C<TT> style of view rendering |
437 | for this tutorial: |
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438 | |
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439 | $ script/myapp_create.pl view HTML TT |
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440 | exists "/home/me/MyApp/script/../lib/MyApp/View" |
441 | exists "/home/me/MyApp/script/../t" |
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442 | created "/home/me/MyApp/script/../lib/MyApp/View/HTML.pm" |
443 | created "/home/me/MyApp/script/../t/view_HTML.t" |
444 | |
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445 | This simply creates a view called C<HTML> in a file called C<HTML.pm> |
446 | (the first argument). It is now up to you to decide how you want to |
447 | structure your view layout. For the tutorial, we will start with a very |
448 | simple TT template to initially demonstrate the concepts, but quickly |
449 | migrate to a more typical "wrapper page" type of configuration (where |
450 | the "wrapper" controls the overall "look and feel" of your site from a |
451 | single file or set of files). |
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452 | |
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453 | Edit C<lib/MyApp/View/HTML.pm> and you should see something similar to |
454 | the following: |
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455 | |
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456 | __PACKAGE__->config( |
457 | TEMPLATE_EXTENSION => '.tt', |
458 | render_die => 1, |
459 | ); |
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460 | |
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461 | And update it to match: |
462 | |
463 | __PACKAGE__->config( |
464 | # Change default TT extension |
465 | TEMPLATE_EXTENSION => '.tt2', |
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466 | render_die => 1, |
467 | ); |
468 | |
469 | This changes the default extension for Template Toolkit from '.tt' to |
470 | '.tt2'. |
471 | |
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472 | You can also configure components in your application class. For |
473 | example, Edit C<lib/MyApp.pm> and you should see that the default: |
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474 | |
475 | __PACKAGE__->setup; |
476 | |
477 | Above this, add config: |
478 | |
479 | __PACKAGE__->config( |
480 | 'View::HTML' => { |
481 | #Set the location for TT files |
482 | INCLUDE_PATH => [ |
483 | __PACKAGE__->path_to( 'root', 'src' ), |
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484 | ], |
c062293d |
485 | }, |
1390ef0e |
486 | ); |
c062293d |
487 | # This line was here already |
488 | __PACKAGE__->setup; |
3533daff |
489 | |
a8f4e284 |
490 | This changes the base directory for your template files from C<root> to |
491 | C<root/src>. |
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492 | |
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493 | The reason to do this outside the C<lib/MyApp/View/HTML.pm> file is that |
494 | the template path is found with the C<path_to> method, to get a path |
495 | relative to the application root (no matter where it is installed), but |
496 | this requires the application to be loaded... |
c062293d |
497 | |
a8f4e284 |
498 | Trying to set this setting in the view means that you have a chicken and |
499 | egg problem, in that the view requires the application to be loaded, but |
500 | loading the application loads the view. |
c062293d |
501 | |
502 | Putting the configuration which depends on the application class into |
503 | that class is the neatest way to avoid this issue. |
504 | |
a8f4e284 |
505 | Please stick with the settings above for the duration of the tutorial, |
506 | but feel free to use whatever options you desire in your applications |
507 | (as with most things Perl, there's more than one way to do it...). |
1390ef0e |
508 | |
a8f4e284 |
509 | B<Note:> We will use C<root/src> as the base directory for our template |
510 | files, with a full naming convention of |
511 | C<root/src/_controller_name_/_action_name_.tt2>. Another popular option |
512 | is to use C<root/> as the base (with a full filename pattern of |
acbd7bdd |
513 | C<root/_controller_name_/_action_name_.tt2>). |
514 | |
a8f4e284 |
515 | |
1390ef0e |
516 | =head2 Create a TT Template Page |
3533daff |
517 | |
518 | First create a directory for book-related TT templates: |
519 | |
1390ef0e |
520 | $ mkdir -p root/src/books |
3533daff |
521 | |
522 | Then create C<root/src/books/list.tt2> in your editor and enter: |
523 | |
524 | [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%] |
525 | [% # see this "chomping" in your browser because HTML ignores blank lines, but -%] |
526 | [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%] |
527 | [%- # optional, but both the beginning and the ending TT tags support chomping. -%] |
528 | |
1390ef0e |
529 | [% # Provide a title -%] |
3533daff |
530 | [% META title = 'Book List' -%] |
531 | |
532 | <table> |
533 | <tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr> |
534 | [% # Display each book in a table row %] |
535 | [% FOREACH book IN books -%] |
536 | <tr> |
537 | <td>[% book.title %]</td> |
538 | <td>[% book.rating %]</td> |
a46b474e |
539 | <td></td> |
3533daff |
540 | </tr> |
541 | [% END -%] |
542 | </table> |
543 | |
544 | As indicated by the inline comments above, the C<META title> line uses |
1390ef0e |
545 | TT's META feature to provide a title to the "wrapper" that we will |
546 | create later. Meanwhile, the C<FOREACH> loop iterates through each |
547 | C<book> model object and prints the C<title> and C<rating> fields. |
3533daff |
548 | |
4d63a0d5 |
549 | The C<[%> and C<%]> tags are used to delimit Template Toolkit code. TT |
550 | supports a wide variety of directives for "calling" other files, |
551 | looping, conditional logic, etc. In general, TT simplifies the usual |
444d6b27 |
552 | range of Perl operators down to the single dot (".") operator. This |
4d63a0d5 |
553 | applies to operations as diverse as method calls, hash lookups, and list |
554 | index values (see |
a8f4e284 |
555 | L<https://metacpan.org/module/Template::Manual::Variables> for details |
556 | and examples). In addition to the usual L<Template> module Pod |
4d63a0d5 |
557 | documentation, you can access the TT manual at |
8c848468 |
558 | L<https://metacpan.org/module/Template::Manual>. |
3533daff |
559 | |
a8f4e284 |
560 | B<TIP:> While you can build all sorts of complex logic into your TT |
561 | templates, you should in general keep the "code" part of your templates |
562 | as simple as possible. If you need more complex logic, create helper |
563 | methods in your model that abstract out a set of code into a single call |
564 | from your TT template. (Note that the same is true of your controller |
565 | logic as well -- complex sections of code in your controllers should |
566 | often be pulled out and placed into your model objects.) In Chapter 4 |
567 | of the tutorial we will explore some extremely helpful and powerful |
568 | features of L<DBIx::Class> that allow you to pull code out of your views |
569 | and controllers and place it where it rightfully belongs in a model |
570 | class. |
1390ef0e |
571 | |
572 | |
573 | =head2 Test Run The Application |
574 | |
575 | To test your work so far, first start the development server: |
576 | |
f058768a |
577 | $ script/myapp_server.pl -r |
1390ef0e |
578 | |
a8f4e284 |
579 | Then point your browser to L<http://localhost:3000> and you should still |
580 | get the Catalyst welcome page. Next, change the URL in your browser to |
581 | L<http://localhost:3000/books/list>. If you have everything working so |
582 | far, you should see a web page that displays nothing other than our |
583 | column headers for "Title", "Rating", and "Author(s)" -- we will not see |
584 | any books until we get the database and model working below. |
1390ef0e |
585 | |
586 | If you run into problems getting your application to run correctly, it |
587 | might be helpful to refer to some of the debugging techniques covered in |
fce83e5f |
588 | the L<Debugging|Catalyst::Manual::Tutorial::07_Debugging> chapter of the |
1390ef0e |
589 | tutorial. |
3533daff |
590 | |
591 | |
592 | =head1 CREATE A SQLITE DATABASE |
593 | |
594 | In this step, we make a text file with the required SQL commands to |
a8f4e284 |
595 | create a database table and load some sample data. We will use SQLite |
596 | (L<http://www.sqlite.org>), a popular database that is lightweight and |
597 | easy to use. Be sure to get at least version 3. Open C<myapp01.sql> in |
598 | your editor and enter: |
3533daff |
599 | |
600 | -- |
601 | -- Create a very simple database to hold book and author information |
602 | -- |
f058768a |
603 | PRAGMA foreign_keys = ON; |
3b1fa91b |
604 | CREATE TABLE book ( |
3533daff |
605 | id INTEGER PRIMARY KEY, |
606 | title TEXT , |
607 | rating INTEGER |
608 | ); |
3b1fa91b |
609 | -- 'book_author' is a many-to-many join table between books & authors |
610 | CREATE TABLE book_author ( |
b66dd084 |
611 | book_id INTEGER REFERENCES book(id) ON DELETE CASCADE ON UPDATE CASCADE, |
612 | author_id INTEGER REFERENCES author(id) ON DELETE CASCADE ON UPDATE CASCADE, |
3533daff |
613 | PRIMARY KEY (book_id, author_id) |
614 | ); |
3b1fa91b |
615 | CREATE TABLE author ( |
3533daff |
616 | id INTEGER PRIMARY KEY, |
617 | first_name TEXT, |
618 | last_name TEXT |
619 | ); |
620 | --- |
621 | --- Load some sample data |
622 | --- |
3b1fa91b |
623 | INSERT INTO book VALUES (1, 'CCSP SNRS Exam Certification Guide', 5); |
624 | INSERT INTO book VALUES (2, 'TCP/IP Illustrated, Volume 1', 5); |
625 | INSERT INTO book VALUES (3, 'Internetworking with TCP/IP Vol.1', 4); |
626 | INSERT INTO book VALUES (4, 'Perl Cookbook', 5); |
627 | INSERT INTO book VALUES (5, 'Designing with Web Standards', 5); |
628 | INSERT INTO author VALUES (1, 'Greg', 'Bastien'); |
629 | INSERT INTO author VALUES (2, 'Sara', 'Nasseh'); |
630 | INSERT INTO author VALUES (3, 'Christian', 'Degu'); |
631 | INSERT INTO author VALUES (4, 'Richard', 'Stevens'); |
632 | INSERT INTO author VALUES (5, 'Douglas', 'Comer'); |
633 | INSERT INTO author VALUES (6, 'Tom', 'Christiansen'); |
634 | INSERT INTO author VALUES (7, 'Nathan', 'Torkington'); |
635 | INSERT INTO author VALUES (8, 'Jeffrey', 'Zeldman'); |
636 | INSERT INTO book_author VALUES (1, 1); |
637 | INSERT INTO book_author VALUES (1, 2); |
638 | INSERT INTO book_author VALUES (1, 3); |
639 | INSERT INTO book_author VALUES (2, 4); |
640 | INSERT INTO book_author VALUES (3, 5); |
641 | INSERT INTO book_author VALUES (4, 6); |
642 | INSERT INTO book_author VALUES (4, 7); |
643 | INSERT INTO book_author VALUES (5, 8); |
3533daff |
644 | |
3533daff |
645 | Then use the following command to build a C<myapp.db> SQLite database: |
646 | |
647 | $ sqlite3 myapp.db < myapp01.sql |
648 | |
649 | If you need to create the database more than once, you probably want to |
650 | issue the C<rm myapp.db> command to delete the database before you use |
1390ef0e |
651 | the C<sqlite3 myapp.db E<lt> myapp01.sql> command. |
3533daff |
652 | |
653 | Once the C<myapp.db> database file has been created and initialized, you |
654 | can use the SQLite command line environment to do a quick dump of the |
655 | database contents: |
656 | |
657 | $ sqlite3 myapp.db |
f058768a |
658 | SQLite version 3.6.22 |
3533daff |
659 | Enter ".help" for instructions |
f058768a |
660 | Enter SQL statements terminated with a ";" |
3b1fa91b |
661 | sqlite> select * from book; |
3533daff |
662 | 1|CCSP SNRS Exam Certification Guide|5 |
663 | 2|TCP/IP Illustrated, Volume 1|5 |
664 | 3|Internetworking with TCP/IP Vol.1|4 |
665 | 4|Perl Cookbook|5 |
666 | 5|Designing with Web Standards|5 |
667 | sqlite> .q |
668 | $ |
669 | |
670 | Or: |
671 | |
3b1fa91b |
672 | $ sqlite3 myapp.db "select * from book" |
3533daff |
673 | 1|CCSP SNRS Exam Certification Guide|5 |
674 | 2|TCP/IP Illustrated, Volume 1|5 |
675 | 3|Internetworking with TCP/IP Vol.1|4 |
676 | 4|Perl Cookbook|5 |
677 | 5|Designing with Web Standards|5 |
678 | |
679 | As with most other SQL tools, if you are using the full "interactive" |
680 | environment you need to terminate your SQL commands with a ";" (it's not |
681 | required if you do a single SQL statement on the command line). Use |
682 | ".q" to exit from SQLite from the SQLite interactive mode and return to |
683 | your OS command prompt. |
684 | |
a8f4e284 |
685 | Please note that here we have chosen to use 'singular' table names. This |
686 | is because the default inflection code for older versions of |
687 | L<DBIx::Class::Schema::Loader> does NOT handle plurals. There has been |
688 | much philosophical discussion on whether table names should be plural or |
689 | singular. There is no one correct answer, as long as one makes a choice |
690 | and remains consistent with it. If you prefer plural table names (e.g. |
691 | you think that they are easier to read) then see the documentation in |
658b8c29 |
692 | L<DBIx::Class::Schema::Loader::Base/naming> (version 0.05 or greater). |
3b1fa91b |
693 | |
a8f4e284 |
694 | For using other databases, such as PostgreSQL or MySQL, see |
3ab6187c |
695 | L<Appendix 2|Catalyst::Manual::Tutorial::10_Appendices>. |
3533daff |
696 | |
acbd7bdd |
697 | |
8a472b34 |
698 | =head1 DATABASE ACCESS WITH DBIx::Class |
3533daff |
699 | |
a8f4e284 |
700 | Catalyst can be used with virtually any form of datastore available via |
701 | Perl. For example, L<Catalyst::Model::DBI|Catalyst::Model::DBI> can be |
702 | used to access databases through the traditional Perl L<DBI> interface |
703 | or you can use a model to access files of any type on the filesystem. |
704 | However, most Catalyst applications use some form of object-relational |
705 | mapping (ORM) technology to create objects associated with tables in a |
706 | relational database. Matt Trout's L<DBIx::Class|DBIx::Class> |
707 | (abbreviated as "DBIC") has rapidly emerged as the Perl-based ORM |
708 | technology of choice. Most new Catalyst applications rely on |
709 | DBIx::Class, as will this tutorial. |
710 | |
711 | Although DBIx::Class has included support for a C<create=dynamic> mode |
712 | to automatically read the database structure every time the application |
713 | starts, its use is no longer recommended. While it can make for |
714 | "flashy" demos, the use of the C<create=static> mode we use below can be |
715 | implemented just as quickly and provides many advantages (such as the |
716 | ability to add your own methods to the overall DBIC framework, a |
717 | technique that we see in Chapter 4). |
3533daff |
718 | |
1390ef0e |
719 | |
a46b474e |
720 | =head2 Make Sure You Have a Recent Version of the DBIx::Class Model |
27909ed4 |
721 | |
722 | First, let's be sure we have a recent version of the DBIC helper, |
a8f4e284 |
723 | L<Catalyst::Model::DBIC::Schema>, so that we can take advantage of some |
724 | recent enhancements in how foreign keys are handled with SQLite. To |
725 | check your version, run this command: |
27909ed4 |
726 | |
727 | $ perl -MCatalyst::Model::DBIC::Schema -e \ |
728 | 'print "$Catalyst::Model::DBIC::Schema::VERSION\n"' |
f33d1dd7 |
729 | 0.4 |
27909ed4 |
730 | |
a8f4e284 |
731 | Please note the '\' above. Depending on your environment, you might be |
732 | able to cut and paste the text as shown or need to remove the '\' |
fce83e5f |
733 | character to that the command is all on a single line. |
3b1fa91b |
734 | |
b9e431e3 |
735 | If you are following along in Debian 6, you should have version 0.40 or |
a8f4e284 |
736 | higher (shown above as "0.4" with the tailing zero removed). If you have |
737 | less than v0.39, you will need to run this command to install it |
738 | directly from CPAN: |
27909ed4 |
739 | |
3e008853 |
740 | $ cpan -i Catalyst::Model::DBIC::Schema |
27909ed4 |
741 | |
a8f4e284 |
742 | And re-run the version print command to verify that you are now at 0.39 |
743 | or higher. |
f058768a |
744 | |
745 | In addition, since we are using SQLite's foreign key support here, |
746 | please be sure that you use version C<1.27> of L<DBD::SQLite> or later: |
747 | |
748 | $ perl -MDBD::SQLite -e 'print "$DBD::SQLite::VERSION\n"' |
749 | 1.29 |
750 | |
751 | Upgrade if you are not at version C<1.27> or higher. |
27909ed4 |
752 | |
a8f4e284 |
753 | Also, remember to put a line requiring the version of the module you |
754 | just installed into your Makefile.PL |
27909ed4 |
755 | |
a46b474e |
756 | =head2 Create Static DBIx::Class Schema Files |
27909ed4 |
757 | |
a8f4e284 |
758 | Before you continue, make sure your C<myapp.db> database file is in the |
759 | application's topmost directory. Now use the model helper with the |
760 | C<create=static> option to read the database with |
761 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> and |
27909ed4 |
762 | automatically build the required files for us: |
3533daff |
763 | |
4ab6212d |
764 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \ |
b66dd084 |
765 | create=static dbi:SQLite:myapp.db \ |
766 | on_connect_do="PRAGMA foreign_keys = ON" |
1390ef0e |
767 | exists "/home/me/MyApp/script/../lib/MyApp/Model" |
768 | exists "/home/me/MyApp/script/../t" |
27909ed4 |
769 | Dumping manual schema for MyApp::Schema to directory /home/me/MyApp/script/../lib ... |
770 | Schema dump completed. |
1390ef0e |
771 | created "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm" |
772 | created "/home/me/MyApp/script/../t/model_DB.t" |
3533daff |
773 | |
a8f4e284 |
774 | Please note the '\' above. Depending on your environment, you might be |
775 | able to cut and paste the text as shown or need to remove the '\' |
fce83e5f |
776 | character to that the command is all on a single line. |
3b1fa91b |
777 | |
27909ed4 |
778 | The C<script/myapp_create.pl> command breaks down like this: |
779 | |
780 | =over 4 |
781 | |
782 | =item * |
783 | |
a8f4e284 |
784 | C<DB> is the name of the model class to be created by the helper in |
27909ed4 |
785 | C<lib/MyApp/Model>. |
786 | |
787 | =item * |
788 | |
789 | C<DBIC::Schema> is the type of the model to create. |
790 | |
791 | =item * |
792 | |
793 | C<MyApp::Schema> is the name of the DBIC schema file written to |
794 | C<lib/MyApp/Schema.pm>. |
795 | |
796 | =item * |
797 | |
a8f4e284 |
798 | C<create=static> causes |
799 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to load the |
800 | schema as it runs and then write that information out into files. |
27909ed4 |
801 | |
802 | =item * |
803 | |
a8f4e284 |
804 | C<dbi:SQLite:myapp.db> is the standard DBI connect string for use with |
805 | SQLite. |
27909ed4 |
806 | |
f058768a |
807 | =item * |
808 | |
a8f4e284 |
809 | And finally, the C<on_connect_do> string requests that |
810 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> create |
811 | foreign key relationships for us (this is not needed for databases such |
812 | as PostgreSQL and MySQL, but is required for SQLite). If you take a look |
813 | at C<lib/MyApp/Model/DB.pm>, you will see that the SQLite pragma is |
814 | propogated to the Model, so that SQLite's recent (and optional) foreign |
815 | key enforcement is enabled at the start of every database connection. |
f058768a |
816 | |
817 | |
27909ed4 |
818 | =back |
819 | |
a8f4e284 |
820 | If you look in the C<lib/MyApp/Schema.pm> file, you will find that it |
821 | only contains a call to the C<load_namespaces> method. You will also |
822 | find that C<lib/MyApp> contains a C<Schema> subdirectory, which then has |
823 | a subdirectory called "Result". This "Result" subdirectory then has |
824 | files named according to each of the tables in our simple database |
825 | (C<Author.pm>, C<BookAuthor.pm>, and C<Book.pm>). These three files are |
826 | called "Result Classes" in DBIx::Class nomenclature. Although the Result |
827 | Class files are named after tables in our database, the classes |
828 | correspond to the I<row-level data> that is returned by DBIC (more on |
829 | this later, especially in |
3ab6187c |
830 | L<Catalyst::Manual::Tutorial::04_BasicCRUD/EXPLORING THE POWER OF DBIC>). |
27909ed4 |
831 | |
a8f4e284 |
832 | The idea with the Result Source files created under |
833 | C<lib/MyApp/Schema/Result> by the C<create=static> option is to only |
834 | edit the files below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> |
835 | warning. If you place all of your changes below that point in the file, |
836 | you can regenerate the automatically created information at the top of |
837 | each file should your database structure get updated. |
838 | |
839 | Also note the "flow" of the model information across the various files |
840 | and directories. Catalyst will initially load the model from |
841 | C<lib/MyApp/Model/DB.pm>. This file contains a reference to |
842 | C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, the call |
843 | to C<load_namespaces> in C<Schema.pm> will load each of the "Result |
844 | Class" files from the C<lib/MyApp/Schema/Result> subdirectory. The |
845 | final outcome is that Catalyst will dynamically create three |
846 | table-specific Catalyst models every time the application starts (you |
847 | can see these three model files listed in the debug output generated |
27909ed4 |
848 | when you launch the application). |
849 | |
a8f4e284 |
850 | B<NOTE:> Older versions of |
851 | L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> use the |
852 | deprecated DBIx::Class C<load_classes> technique instead of the newer |
853 | C<load_namespaces>. For new applications, please try to use |
854 | C<load_namespaces> since it more easily supports a very useful DBIC |
855 | technique called "ResultSet Classes." If you need to convert an |
856 | existing application from "load_classes" to "load_namespaces," you can |
b66dd084 |
857 | use this process to automate the migration, but first make sure you have |
858 | version C<0.39> of L<Catalyst::Model::DBIC::Schema> and |
859 | L<DBIx::Class::Schema::Loader> version C<0.05000> or later. |
27909ed4 |
860 | |
b66dd084 |
861 | $ # Re-run the helper to upgrade for you |
27909ed4 |
862 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \ |
b66dd084 |
863 | create=static naming=current use_namespaces=1 \ |
864 | dbi:SQLite:myapp.db \ |
865 | on_connect_do="PRAGMA foreign_keys = ON" |
dc9a0503 |
866 | |
f058768a |
867 | |
1390ef0e |
868 | =head1 ENABLE THE MODEL IN THE CONTROLLER |
869 | |
a8f4e284 |
870 | Open C<lib/MyApp/Controller/Books.pm> and un-comment the model code we |
acbd7bdd |
871 | left disabled earlier so that your version matches the following (un- |
a8f4e284 |
872 | comment the line containing C<[$c-E<gt>model('DB::Book')-E<gt>all]> and |
873 | delete the next 2 lines): |
1390ef0e |
874 | |
875 | =head2 list |
876 | |
877 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
878 | |
879 | =cut |
880 | |
f058768a |
881 | sub list :Local { |
1390ef0e |
882 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
883 | # 'Context' that's used to 'glue together' the various components |
884 | # that make up the application |
885 | my ($self, $c) = @_; |
886 | |
f058768a |
887 | # Retrieve all of the book records as book model objects and store |
888 | # in the stash where they can be accessed by the TT template |
0ed3df53 |
889 | $c->stash(books => [$c->model('DB::Book')->all]); |
1390ef0e |
890 | |
891 | # Set the TT template to use. You will almost always want to do this |
892 | # in your action methods (action methods respond to user input in |
893 | # your controllers). |
61cb69fd |
894 | $c->stash(template => 'books/list.tt2'); |
1390ef0e |
895 | } |
896 | |
a8f4e284 |
897 | B<TIP>: You may see the C<$c-E<gt>model('DB::Book')> un-commented above |
898 | written as C<$c-E<gt>model('DB')-E<gt>resultset('Book')>. The two are |
899 | equivalent. Either way, C<$c-E<gt>model> returns a |
900 | L<DBIx::Class::ResultSet|DBIx::Class::ResultSet> which handles queries |
901 | against the database and iterating over the set of results that is |
c93b5eaa |
902 | returned. |
903 | |
a8f4e284 |
904 | We are using the C<-E<gt>all> to fetch all of the books. DBIC supports |
905 | a wide variety of more advanced operations to easily do things like |
906 | filtering and sorting the results. For example, the following could be |
907 | used to sort the results by descending title: |
c93b5eaa |
908 | |
3b1fa91b |
909 | $c->model('DB::Book')->search({}, {order_by => 'title DESC'}); |
c93b5eaa |
910 | |
a8f4e284 |
911 | Some other examples are provided in |
912 | L<DBIx::Class::Manual::Cookbook/Complex WHERE clauses>, with additional |
913 | information found at L<DBIx::Class::ResultSet/search>, |
914 | L<DBIx::Class::Manual::FAQ/Searching>, |
915 | L<DBIx::Class::Manual::Intro|DBIx::Class::Manual::Intro> and |
916 | L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>. |
1390ef0e |
917 | |
918 | |
919 | =head2 Test Run The Application |
3533daff |
920 | |
a8f4e284 |
921 | First, let's enable an environment variable that causes DBIx::Class to |
922 | dump the SQL statements used to access the database. This is a helpful |
923 | trick when you are trying to debug your database-oriented code. Press |
924 | C<Ctrl-C> to break out of the development server and enter: |
3533daff |
925 | |
926 | $ export DBIC_TRACE=1 |
f058768a |
927 | $ script/myapp_server.pl -r |
f33d1dd7 |
928 | |
4d63a0d5 |
929 | This assumes you are using bash as your shell -- adjust accordingly if |
3533daff |
930 | you are using a different shell (for example, under tcsh, use |
931 | C<setenv DBIC_TRACE 1>). |
932 | |
d0496197 |
933 | B<NOTE:> You can also set this in your code using |
3533daff |
934 | C<$class-E<gt>storage-E<gt>debug(1);>. See |
935 | L<DBIx::Class::Manual::Troubleshooting> for details (including options |
a8f4e284 |
936 | to log to a file instead of displaying to the Catalyst development |
937 | server log). |
3533daff |
938 | |
1390ef0e |
939 | Then launch the Catalyst development server. The log output should |
940 | display something like: |
3533daff |
941 | |
f058768a |
942 | $ script/myapp_server.pl -r |
3533daff |
943 | [debug] Debug messages enabled |
1390ef0e |
944 | [debug] Statistics enabled |
3533daff |
945 | [debug] Loaded plugins: |
946 | .----------------------------------------------------------------------------. |
a467a714 |
947 | | Catalyst::Plugin::ConfigLoader 0.27 | |
948 | | Catalyst::Plugin::StackTrace 0.11 | |
3533daff |
949 | '----------------------------------------------------------------------------' |
950 | |
951 | [debug] Loaded dispatcher "Catalyst::Dispatcher" |
952 | [debug] Loaded engine "Catalyst::Engine::HTTP" |
953 | [debug] Found home "/home/me/MyApp" |
45d511e0 |
954 | [debug] Loaded Config "/home/me/MyApp/myapp.conf" |
3533daff |
955 | [debug] Loaded components: |
956 | .-----------------------------------------------------------------+----------. |
957 | | Class | Type | |
958 | +-----------------------------------------------------------------+----------+ |
959 | | MyApp::Controller::Books | instance | |
960 | | MyApp::Controller::Root | instance | |
d0496197 |
961 | | MyApp::Model::DB | instance | |
3b1fa91b |
962 | | MyApp::Model::DB::Author | class | |
963 | | MyApp::Model::DB::Book | class | |
964 | | MyApp::Model::DB::BookAuthor | class | |
1edbdee6 |
965 | | MyApp::View::HTML | instance | |
3533daff |
966 | '-----------------------------------------------------------------+----------' |
967 | |
968 | [debug] Loaded Private actions: |
969 | .----------------------+--------------------------------------+--------------. |
970 | | Private | Class | Method | |
971 | +----------------------+--------------------------------------+--------------+ |
972 | | /default | MyApp::Controller::Root | default | |
973 | | /end | MyApp::Controller::Root | end | |
1390ef0e |
974 | | /index | MyApp::Controller::Root | index | |
3533daff |
975 | | /books/index | MyApp::Controller::Books | index | |
976 | | /books/list | MyApp::Controller::Books | list | |
977 | '----------------------+--------------------------------------+--------------' |
978 | |
979 | [debug] Loaded Path actions: |
980 | .-------------------------------------+--------------------------------------. |
981 | | Path | Private | |
982 | +-------------------------------------+--------------------------------------+ |
1390ef0e |
983 | | / | /default | |
984 | | / | /index | |
985 | | /books | /books/index | |
3533daff |
986 | | /books/list | /books/list | |
987 | '-------------------------------------+--------------------------------------' |
988 | |
f058768a |
989 | [info] MyApp powered by Catalyst 5.80020 |
acbd7bdd |
990 | You can connect to your server at http://debian:3000 |
3533daff |
991 | |
a8f4e284 |
992 | B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from the |
993 | 'base' directory of your application, not inside the C<script> directory |
994 | itself or it will not be able to locate the C<myapp.db> database file. |
995 | You can use a fully qualified or a relative path to locate the database |
996 | file, but we did not specify that when we ran the model helper earlier. |
3533daff |
997 | |
998 | Some things you should note in the output above: |
999 | |
1000 | =over 4 |
1001 | |
1390ef0e |
1002 | =item * |
3533daff |
1003 | |
1390ef0e |
1004 | Catalyst::Model::DBIC::Schema dynamically created three model classes, |
1005 | one to represent each of the three tables in our database |
a8f4e284 |
1006 | (C<MyApp::Model::DB::Author>, C<MyApp::Model::DB::BookAuthor>, and |
1007 | C<MyApp::Model::DB::Book>). |
3533daff |
1008 | |
1390ef0e |
1009 | =item * |
3533daff |
1010 | |
1011 | The "list" action in our Books controller showed up with a path of |
1012 | C</books/list>. |
1013 | |
1014 | =back |
1015 | |
1016 | Point your browser to L<http://localhost:3000> and you should still get |
1017 | the Catalyst welcome page. |
1018 | |
1019 | Next, to view the book list, change the URL in your browser to |
1020 | L<http://localhost:3000/books/list>. You should get a list of the five |
1390ef0e |
1021 | books loaded by the C<myapp01.sql> script above without any formatting. |
1022 | The rating for each book should appear on each row, but the "Author(s)" |
191dee29 |
1023 | column will still be blank (we will fill that in later). |
3533daff |
1024 | |
a8f4e284 |
1025 | Also notice in the output of the C<script/myapp_server.pl> that |
a46b474e |
1026 | DBIx::Class used the following SQL to retrieve the data: |
3533daff |
1027 | |
fce83e5f |
1028 | SELECT me.id, me.title, me.rating FROM book me |
3533daff |
1029 | |
1030 | because we enabled DBIC_TRACE. |
1031 | |
0c51850e |
1032 | You now have the beginnings of a simple but workable web application. |
a8f4e284 |
1033 | Continue on to future sections and we will develop the application more |
1034 | fully. |
3533daff |
1035 | |
1036 | |
1390ef0e |
1037 | =head1 CREATE A WRAPPER FOR THE VIEW |
1038 | |
a8f4e284 |
1039 | When using TT, you can (and should) create a wrapper that will literally |
1040 | wrap content around each of your templates. This is certainly useful as |
1041 | you have one main source for changing things that will appear across |
1042 | your entire site/application instead of having to edit many individual |
1043 | files. |
1390ef0e |
1044 | |
1045 | |
1edbdee6 |
1046 | =head2 Configure HTML.pm For The Wrapper |
1390ef0e |
1047 | |
a8f4e284 |
1048 | In order to create a wrapper, you must first edit your TT view and tell |
1049 | it where to find your wrapper file. |
1390ef0e |
1050 | |
a8f4e284 |
1051 | Edit your TT view in C<lib/MyApp/View/HTML.pm> and change it to match |
1052 | the following: |
1390ef0e |
1053 | |
1054 | __PACKAGE__->config( |
1055 | # Change default TT extension |
1056 | TEMPLATE_EXTENSION => '.tt2', |
1057 | # Set the location for TT files |
1058 | INCLUDE_PATH => [ |
c2dfb562 |
1059 | MyApp->path_to( 'root', 'src' ), |
1390ef0e |
1060 | ], |
1061 | # Set to 1 for detailed timer stats in your HTML as comments |
1062 | TIMER => 0, |
1063 | # This is your wrapper template located in the 'root/src' |
1064 | WRAPPER => 'wrapper.tt2', |
1065 | ); |
1066 | |
1067 | |
1068 | =head2 Create the Wrapper Template File and Stylesheet |
1069 | |
1070 | Next you need to set up your wrapper template. Basically, you'll want |
a8f4e284 |
1071 | to take the overall layout of your site and put it into this file. For |
1072 | the tutorial, open C<root/src/wrapper.tt2> and input the following: |
1390ef0e |
1073 | |
1074 | <?xml version="1.0" encoding="UTF-8"?> |
1075 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> |
1076 | <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> |
1077 | <head> |
1078 | <title>[% template.title or "My Catalyst App!" %]</title> |
1079 | <link rel="stylesheet" href="[% c.uri_for('/static/css/main.css') %]" /> |
1080 | </head> |
1081 | |
1082 | <body> |
1083 | <div id="outer"> |
1084 | <div id="header"> |
1085 | [%# Your logo could go here -%] |
1086 | <img src="[% c.uri_for('/static/images/btn_88x31_powered.png') %]" /> |
1087 | [%# Insert the page title -%] |
1088 | <h1>[% template.title or site.title %]</h1> |
1089 | </div> |
1090 | |
1091 | <div id="bodyblock"> |
1092 | <div id="menu"> |
1093 | Navigation: |
1094 | <ul> |
1095 | <li><a href="[% c.uri_for('/books/list') %]">Home</a></li> |
1096 | <li><a href="[% c.uri_for('/') %]" title="Catalyst Welcome Page">Welcome</a></li> |
1390ef0e |
1097 | </ul> |
1098 | </div><!-- end menu --> |
1099 | |
1100 | <div id="content"> |
1101 | [%# Status and error messages %] |
1102 | <span class="message">[% status_msg %]</span> |
1103 | <span class="error">[% error_msg %]</span> |
1104 | [%# This is where TT will stick all of your template's contents. -%] |
1105 | [% content %] |
1106 | </div><!-- end content --> |
1107 | </div><!-- end bodyblock --> |
1108 | |
1109 | <div id="footer">Copyright (c) your name goes here</div> |
c2dfb562 |
1110 | </div><!-- end outer --> |
1390ef0e |
1111 | |
1112 | </body> |
1113 | </html> |
1114 | |
1115 | Notice the status and error message sections in the code above: |
1116 | |
1117 | <span class="status">[% status_msg %]</span> |
1118 | <span class="error">[% error_msg %]</span> |
1119 | |
1120 | If we set either message in the Catalyst stash (e.g., |
a8f4e284 |
1121 | C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it will |
1122 | be displayed whenever any view used by that request is rendered. The |
1123 | C<message> and C<error> CSS styles can be customized to suit your needs |
1124 | in the C<root/static/css/main.css> file we create below. |
1390ef0e |
1125 | |
a8f4e284 |
1126 | B<Notes:> |
1390ef0e |
1127 | |
1128 | =over 4 |
1129 | |
1130 | =item * |
1131 | |
a8f4e284 |
1132 | The Catalyst stash only lasts for a single HTTP request. If you need to |
1133 | retain information across requests you can use |
1390ef0e |
1134 | L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use |
4b4d3884 |
1135 | Catalyst sessions in the Authentication chapter of the tutorial). |
1390ef0e |
1136 | |
1137 | =item * |
1138 | |
a8f4e284 |
1139 | Although it is beyond the scope of this tutorial, you may wish to use a |
1140 | JavaScript or AJAX tool such as jQuery (L<http://www.jquery.com>) or |
1390ef0e |
1141 | Dojo (L<http://www.dojotoolkit.org>). |
1142 | |
1143 | =back |
1144 | |
1145 | |
1146 | =head3 Create A Basic Stylesheet |
1147 | |
1148 | First create a central location for stylesheets under the static |
1149 | directory: |
1150 | |
1151 | $ mkdir root/static/css |
1152 | |
1153 | Then open the file C<root/static/css/main.css> (the file referenced in |
1154 | the stylesheet href link of our wrapper above) and add the following |
1155 | content: |
1156 | |
1157 | #header { |
1158 | text-align: center; |
1159 | } |
1160 | #header h1 { |
1161 | margin: 0; |
1162 | } |
1163 | #header img { |
1164 | float: right; |
1165 | } |
1166 | #footer { |
1167 | text-align: center; |
1168 | font-style: italic; |
1169 | padding-top: 20px; |
1170 | } |
1171 | #menu { |
1172 | font-weight: bold; |
1173 | background-color: #ddd; |
1174 | } |
1175 | #menu ul { |
1176 | list-style: none; |
1177 | float: left; |
1178 | margin: 0; |
1179 | padding: 0 0 50% 5px; |
1180 | font-weight: normal; |
1181 | background-color: #ddd; |
1182 | width: 100px; |
1183 | } |
1184 | #content { |
1185 | margin-left: 120px; |
1186 | } |
1187 | .message { |
1188 | color: #390; |
1189 | } |
1190 | .error { |
1191 | color: #f00; |
1192 | } |
1193 | |
1194 | You may wish to check out a "CSS Framework" like Emastic |
a8f4e284 |
1195 | (L<http://code.google.com/p/emastic/>) as a way to quickly provide lots |
1196 | of high-quality CSS functionality. |
1390ef0e |
1197 | |
1198 | |
1199 | =head2 Test Run The Application |
1200 | |
a8f4e284 |
1201 | Hit "Reload" in your web browser and you should now see a formatted |
1202 | version of our basic book list. (Again, the development server should |
1203 | have automatically restarted when you made changes to |
1204 | C<lib/MyApp/View/HTML.pm>. If you are not using the "-r" option, you |
1205 | will need to hit C<Ctrl-C> and manually restart it. Also note that the |
1206 | development server does I<NOT> need to restart for changes to the TT and |
1207 | static files we created and edited in the C<root> directory -- those |
1208 | updates are handled on a per-request basis.) |
f058768a |
1209 | |
a8f4e284 |
1210 | Although our wrapper and stylesheet are obviously very simple, you |
1211 | should see how it allows us to control the overall look of an entire |
1212 | website from two central files. To add new pages to the site, just |
1213 | provide a template that fills in the C<content> section of our wrapper |
1214 | template -- the wrapper will provide the overall feel of the page. |
1390ef0e |
1215 | |
1216 | |
a46b474e |
1217 | =head2 Updating the Generated DBIx::Class Result Class Files |
3533daff |
1218 | |
a8f4e284 |
1219 | If you take a look at the Schema files automatically generated by |
1220 | L<DBIx::Class::Schema::Loader>, you will see that it has already defined |
1221 | C<has_many> and C<belongs_to> relationships on each side of our foreign |
1222 | keys. For example, take a look at C<lib/MyApp/Schema/Result/Book.pm> and |
1223 | notice the following code: |
f058768a |
1224 | |
1225 | =head1 RELATIONS |
1226 | |
1227 | =head2 book_authors |
1228 | |
1229 | Type: has_many |
1230 | |
1231 | Related object: L<MyApp::Schema::Result::BookAuthor> |
1232 | |
1233 | =cut |
1234 | |
1235 | __PACKAGE__->has_many( |
1236 | "book_authors", |
1237 | "MyApp::Schema::Result::BookAuthor", |
1238 | { "foreign.book_id" => "self.id" }, |
1239 | ); |
1240 | |
a8f4e284 |
1241 | Each C<Book> "has_many" C<book_authors>, where C<BookAuthor> is the |
1242 | many-to-many table that allows each Book to have multiple Authors, and |
1243 | each Author to have mulitple books. The arguments to C<has_many> are: |
f058768a |
1244 | |
1245 | =over 4 |
1246 | |
1247 | =item * |
1248 | |
a8f4e284 |
1249 | C<book_authors> - The name for this relationship. DBIC will create an |
1250 | accessor on the C<Books> DBIC Row object with this name. |
f058768a |
1251 | |
1252 | =item * |
1253 | |
a8f4e284 |
1254 | C<MyApp::Schema::Result::BookAuthor> - The name of the DBIC model class |
1255 | referenced by this C<has_many> relationship. |
f058768a |
1256 | |
1257 | =item * |
1258 | |
a8f4e284 |
1259 | C<foreign.book_id> - C<book_id> is the name of the foreign key column in |
1260 | the I<foreign> table that points back to this table. |
f058768a |
1261 | |
1262 | =item * |
1263 | |
a8f4e284 |
1264 | C<self.id> - C<id> is the name of the column in I<this> table that is |
1265 | referenced by the foreign key. |
f058768a |
1266 | |
1267 | =back |
1268 | |
a8f4e284 |
1269 | See L<DBIx::Class::Relationship/has_many> for additional information. |
1270 | Note that you might see a "hand coded" version of the C<has_many> |
1271 | relationship above expressed as: |
f058768a |
1272 | |
1273 | __PACKAGE__->has_many( |
1274 | "book_authors", |
1275 | "MyApp::Schema::Result::BookAuthor", |
1276 | "book_id", |
1277 | ); |
1278 | |
a8f4e284 |
1279 | Where the third argument is simply the name of the column in the foreign |
1280 | table. However, the hashref syntax used by |
1281 | L<DBIx::Class::Schema::Loader> is more flexible (for example, it can |
1282 | handle "multi-column" foreign keys). |
f058768a |
1283 | |
a8f4e284 |
1284 | B<Note:> If you are using older versions of SQLite and related DBIC |
1285 | tools, you will need to manually define your C<has_many> and |
1286 | C<belongs_to> relationships. We recommend upgrading to the versions |
1287 | specified above. :-) |
f058768a |
1288 | |
a8f4e284 |
1289 | Have a look at C<lib/MyApp/Schema/Result/BookAuthor.pm> and notice that |
1290 | there is a C<belongs_to> relationship defined that acts as the "mirror |
1291 | image" to the C<has_many> relationship we just looked at above: |
f058768a |
1292 | |
1293 | =head1 RELATIONS |
1294 | |
1295 | =head2 book |
1296 | |
1297 | Type: belongs_to |
1298 | |
1299 | Related object: L<MyApp::Schema::Result::Book> |
1300 | |
1301 | =cut |
1302 | |
1303 | __PACKAGE__->belongs_to( |
1304 | "book", |
1305 | "MyApp::Schema::Result::Book", |
1306 | { id => "book_id" }, |
1307 | { join_type => "LEFT" }, |
1308 | ); |
1309 | |
a8f4e284 |
1310 | The arguments are similar, but see |
f058768a |
1311 | L<DBIx::Class::Relationship/belongs_to> for the details. |
f33d1dd7 |
1312 | |
a8f4e284 |
1313 | Although recent versions of SQLite and L<DBIx::Class::Schema::Loader> |
1314 | automatically handle the C<has_many> and C<belongs_to> relationships, |
7040a6cd |
1315 | C<many_to_many> relationship bridges (not technically a relationship) |
a8f4e284 |
1316 | currently need to be manually inserted. To add a C<many_to_many> |
1317 | relationship bridge, first edit C<lib/MyApp/Schema/Result/Book.pm> and |
1318 | add the following text below the C<# You can replace this text...> |
1319 | comment: |
3533daff |
1320 | |
3533daff |
1321 | # many_to_many(): |
1322 | # args: |
7040a6cd |
1323 | # 1) Name of relationship bridge, DBIC will create accessor with this name |
1390ef0e |
1324 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
1325 | # 3) Name of belongs_to() relationship in model class of has_many() above |
3533daff |
1326 | # You must already have the has_many() defined to use a many_to_many(). |
fce83e5f |
1327 | __PACKAGE__->many_to_many(authors => 'book_authors', 'author'); |
3533daff |
1328 | |
a8f4e284 |
1329 | B<Note:> Be careful to put this code I<above> the C<1;> at the end of |
1330 | the file. As with any Perl package, we need to end the last line with a |
1331 | statement that evaluates to C<true>. This is customarily done with |
3533daff |
1332 | C<1;> on a line by itself. |
1333 | |
7040a6cd |
1334 | The C<many_to_many> relationship bridge is optional, but it makes it |
a8f4e284 |
1335 | easier to map a book to its collection of authors. Without it, we would |
1336 | have to "walk" through the C<book_author> table as in |
1337 | C<$book-E<gt>book_author-E<gt>first-E<gt>author-E<gt>last_name> (we will |
1338 | see examples on how to use DBIx::Class objects in your code soon, but |
1339 | note that because C<$book-E<gt>book_author> can return multiple authors, |
1340 | we have to use C<first> to display a single author). C<many_to_many> |
1341 | allows us to use the shorter |
1342 | C<$book-E<gt>author-E<gt>first-E<gt>last_name>. Note that you cannot |
1343 | define a C<many_to_many> relationship bridge without also having the |
5a82cb36 |
1344 | C<has_many> relationship in place. |
3533daff |
1345 | |
a8f4e284 |
1346 | Then edit C<lib/MyApp/Schema/Result/Author.pm> and add the reverse |
1347 | C<many_to_many> relationship bridge for C<Author> as follows (again, be |
1348 | careful to put in above the C<1;> but below the C<# DO NOT MODIFY THIS |
1349 | OR ANYTHING ABOVE!> comment): |
3533daff |
1350 | |
3533daff |
1351 | # many_to_many(): |
1352 | # args: |
7040a6cd |
1353 | # 1) Name of relationship bridge, DBIC will create accessor with this name |
3533daff |
1354 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
1390ef0e |
1355 | # 3) Name of belongs_to() relationship in model class of has_many() above |
3533daff |
1356 | # You must already have the has_many() defined to use a many_to_many(). |
fce83e5f |
1357 | __PACKAGE__->many_to_many(books => 'book_authors', 'book'); |
3533daff |
1358 | |
f058768a |
1359 | |
1390ef0e |
1360 | =head2 Run The Application |
3533daff |
1361 | |
4d63a0d5 |
1362 | Run the Catalyst development server script with the C<DBIC_TRACE> option |
1363 | (it might still be enabled from earlier in the tutorial, but here is an |
f33d1dd7 |
1364 | alternate way to specify the trace option just in case): |
3533daff |
1365 | |
f058768a |
1366 | $ DBIC_TRACE=1 script/myapp_server.pl -r |
3533daff |
1367 | |
1390ef0e |
1368 | Make sure that the application loads correctly and that you see the |
a8f4e284 |
1369 | three dynamically created model class (one for each of the Result |
1370 | Classes we created). |
3533daff |
1371 | |
a8f4e284 |
1372 | Then hit the URL L<http://localhost:3000/books/list> with your browser |
f33d1dd7 |
1373 | and be sure that the book list still displays correctly. |
3533daff |
1374 | |
a8f4e284 |
1375 | B<Note:> You will not see the authors yet because the view does not yet |
1376 | use the new relations. Read on to the next section where we update the |
c2dfb562 |
1377 | template to do that. |
3533daff |
1378 | |
1379 | |
1380 | =head1 UPDATING THE VIEW |
1381 | |
a8f4e284 |
1382 | Let's add a new column to our book list page that takes advantage of the |
1383 | relationship information we manually added to our schema files in the |
1384 | previous section. Edit C<root/src/books/list.tt2> and replace the |
1385 | "empty" table cell "<td></td>" with the following: |
3533daff |
1386 | |
acbd7bdd |
1387 | ... |
3533daff |
1388 | <td> |
fce83e5f |
1389 | [% # NOTE: See Chapter 4 for a better way to do this! -%] |
3533daff |
1390 | [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%] |
1391 | [% # loop in 'side effect notation' to load just the last names of the -%] |
6d97b973 |
1392 | [% # authors into the list. Note that the 'push' TT vmethod doesn't return -%] |
3533daff |
1393 | [% # a value, so nothing will be printed here. But, if you have something -%] |
6d97b973 |
1394 | [% # in TT that does return a value and you don't want it printed, you -%] |
1395 | [% # 1) assign it to a bogus value, or -%] |
1396 | [% # 2) use the CALL keyword to call it and discard the return value. -%] |
3533daff |
1397 | [% tt_authors = [ ]; |
1398 | tt_authors.push(author.last_name) FOREACH author = book.authors %] |
1399 | [% # Now use a TT 'virtual method' to display the author count in parens -%] |
1400 | [% # Note the use of the TT filter "| html" to escape dangerous characters -%] |
1401 | ([% tt_authors.size | html %]) |
1402 | [% # Use another TT vmethod to join & print the names & comma separators -%] |
1403 | [% tt_authors.join(', ') | html %] |
1404 | </td> |
acbd7bdd |
1405 | ... |
3533daff |
1406 | |
a8f4e284 |
1407 | B<IMPORTANT NOTE:> Again, you should keep as much "logic code" as |
1408 | possible out of your views. This kind of logic belongs in your model |
1409 | (the same goes for controllers -- keep them as "thin" as possible and |
1410 | push all of the "complicated code" out to your model objects). Avoid |
1411 | code like you see in the previous example -- we are only using it here |
1412 | to show some extra features in TT until we get to the more advanced |
1413 | model features we will see in Chapter 4 (see |
fce83e5f |
1414 | L<Catalyst::Manual::Tutorial::04_BasicCRUD/EXPLORING THE POWER OF DBIC>). |
1415 | |
a8f4e284 |
1416 | Then hit "Reload" in your browser (note that you don't need to reload |
1417 | the development server or use the C<-r> option when updating TT |
1418 | templates) and you should now see the number of authors each book has |
1419 | along with a comma-separated list of the authors' last names. (If you |
1420 | didn't leave the development server running from the previous step, you |
1421 | will obviously need to start it before you can refresh your browser |
1422 | window.) |
1390ef0e |
1423 | |
1424 | If you are still running the development server with C<DBIC_TRACE> |
1425 | enabled, you should also now see five more C<SELECT> statements in the |
1426 | debug output (one for each book as the authors are being retrieved by |
a46b474e |
1427 | DBIx::Class): |
3533daff |
1428 | |
fce83e5f |
1429 | SELECT me.id, me.title, me.rating FROM book me: |
3b1fa91b |
1430 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1431 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '1' |
3b1fa91b |
1432 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1433 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '2' |
3b1fa91b |
1434 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1435 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '3' |
3b1fa91b |
1436 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1437 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '4' |
3b1fa91b |
1438 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1439 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '5' |
c2dfb562 |
1440 | |
a8f4e284 |
1441 | Also note in C<root/src/books/list.tt2> that we are using "| html", a |
1442 | type of TT filter, to escape characters such as E<lt> and E<gt> to < |
1443 | and > and avoid various types of dangerous hacks against your |
1444 | application. In a real application, you would probably want to put "| |
1445 | html" at the end of every field where a user has control over the |
1446 | information that can appear in that field (and can therefore inject |
1447 | markup or code if you don't "neutralize" those fields). In addition to |
1448 | "| html", Template Toolkit has a variety of other useful filters that |
1449 | can found in the documentation for |
c2dfb562 |
1450 | L<Template::Filters|Template::Filters>. |
3533daff |
1451 | |
1452 | |
1390ef0e |
1453 | =head1 RUNNING THE APPLICATION FROM THE COMMAND LINE |
1454 | |
a8f4e284 |
1455 | In some situations, it can be useful to run your application and display |
1456 | a page without using a browser. Catalyst lets you do this using the |
1457 | C<scripts/myapp_test.pl> script. Just supply the URL you wish to |
1458 | display and it will run that request through the normal controller |
1459 | dispatch logic and use the appropriate view to render the output |
1460 | (obviously, complex pages may dump a lot of text to your terminal |
1461 | window). For example, if you type: |
1390ef0e |
1462 | |
1463 | $ script/myapp_test.pl "/books/list" |
1464 | |
1465 | You should get the same text as if you visited |
1466 | L<http://localhost:3000/books/list> with the normal development server |
1467 | and asked your browser to view the page source. |
3533daff |
1468 | |
1390ef0e |
1469 | |
1470 | =head1 OPTIONAL INFORMATION |
1471 | |
4b4d3884 |
1472 | B<NOTE: The rest of this chapter of the tutorial is optional. You can |
3ab6187c |
1473 | skip to Chapter 4, L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD>, |
3533daff |
1474 | if you wish.> |
1475 | |
acbd7bdd |
1476 | |
8a472b34 |
1477 | =head2 Using 'RenderView' for the Default View |
1390ef0e |
1478 | |
1479 | Once your controller logic has processed the request from a user, it |
1480 | forwards processing to your view in order to generate the appropriate |
3533daff |
1481 | response output. Catalyst uses |
a8f4e284 |
1482 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by default |
1483 | to automatically perform this operation. If you look in |
1484 | C<lib/MyApp/Controller/Root.pm>, you should see the empty definition for |
1485 | the C<sub end> method: |
3533daff |
1486 | |
1487 | sub end : ActionClass('RenderView') {} |
1488 | |
1390ef0e |
1489 | The following bullet points provide a quick overview of the |
3533daff |
1490 | C<RenderView> process: |
1491 | |
1492 | =over 4 |
1493 | |
1494 | =item * |
1495 | |
1496 | C<Root.pm> is designed to hold application-wide logic. |
1497 | |
1498 | =item * |
1499 | |
1390ef0e |
1500 | At the end of a given user request, Catalyst will call the most specific |
1501 | C<end> method that's appropriate. For example, if the controller for a |
1502 | request has an C<end> method defined, it will be called. However, if |
1503 | the controller does not define a controller-specific C<end> method, the |
3533daff |
1504 | "global" C<end> method in C<Root.pm> will be called. |
1505 | |
1506 | =item * |
1507 | |
1508 | Because the definition includes an C<ActionClass> attribute, the |
a8f4e284 |
1509 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic will |
1510 | be executed B<after> any code inside the definition of C<sub end> is |
1511 | run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions> for |
1512 | more information on C<ActionClass>. |
3533daff |
1513 | |
1514 | =item * |
1515 | |
1390ef0e |
1516 | Because C<sub end> is empty, this effectively just runs the default |
1517 | logic in C<RenderView>. However, you can easily extend the |
1518 | C<RenderView> logic by adding your own code inside the empty method body |
1519 | (C<{}>) created by the Catalyst Helpers when we first ran the |
1520 | C<catalyst.pl> to initialize our application. See |
1521 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more |
4d63a0d5 |
1522 | detailed information on how to extend C<RenderView> in C<sub end>. |
3533daff |
1523 | |
1524 | =back |
1525 | |
1526 | |
fce83e5f |
1527 | =head2 RenderView's "dump_info" Feature |
1528 | |
a8f4e284 |
1529 | One of the nice features of C<RenderView> is that it automatically |
1530 | allows you to add C<dump_info=1> to the end of any URL for your |
1531 | application and it will force the display of the "exception dump" screen |
1532 | to the client browser. You can try this out by pointing your browser to |
1533 | this URL: |
fce83e5f |
1534 | |
1535 | http://localhost:3000/books/list?dump_info=1 |
1536 | |
1537 | You should get a page with the following message at the top: |
1538 | |
1539 | Caught exception in MyApp::Controller::Root->end "Forced debug - |
1540 | Scrubbed output at /usr/share/perl5/Catalyst/Action/RenderView.pm line 46." |
1541 | |
a8f4e284 |
1542 | Along with a summary of your application's state at the end of the |
1543 | processing for that request. The "Stash" section should show a |
1544 | summarized version of the DBIC book model objects. If desired, you can |
1545 | adjust the summarization logic (called "scrubbing" logic) -- see |
1546 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for |
fce83e5f |
1547 | details. |
1548 | |
a8f4e284 |
1549 | Note that you shouldn't need to worry about "normal clients" using this |
1550 | technique to "reverse engineer" your application -- C<RenderView> only |
1551 | supports the C<dump_info=1> feature when your application is running in |
1552 | C<-Debug> mode (something you won't do once you have your application |
1553 | deployed in production). |
fce83e5f |
1554 | |
1555 | |
3533daff |
1556 | =head2 Using The Default Template Name |
1557 | |
1390ef0e |
1558 | By default, C<Catalyst::View::TT> will look for a template that uses the |
1559 | same name as your controller action, allowing you to save the step of |
1560 | manually specifying the template name in each action. For example, this |
a8f4e284 |
1561 | would allow us to remove the C<$c-E<gt>stash-E<gt>{template} = |
1562 | 'books/list.tt2';> line of our C<list> action in the Books controller. |
1563 | Open C<lib/MyApp/Controller/Books.pm> in your editor and comment out |
1564 | this line to match the following (only the |
1565 | C<$c-E<gt>stash-E<gt>{template}> line has changed): |
3533daff |
1566 | |
1567 | =head2 list |
1568 | |
1569 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
1570 | |
1571 | =cut |
1572 | |
ddfbd850 |
1573 | sub list :Local { |
3533daff |
1574 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
1575 | # 'Context' that's used to 'glue together' the various components |
1576 | # that make up the application |
1577 | my ($self, $c) = @_; |
1578 | |
1579 | # Retrieve all of the book records as book model objects and store in the |
1580 | # stash where they can be accessed by the TT template |
0ed3df53 |
1581 | $c->stash(books => [$c->model('DB::Book')->all]); |
3533daff |
1582 | |
1583 | # Set the TT template to use. You will almost always want to do this |
1584 | # in your action methods (actions methods respond to user input in |
1585 | # your controllers). |
61cb69fd |
1586 | #$c->stash(template => 'books/list.tt2'); |
3533daff |
1587 | } |
1588 | |
3533daff |
1589 | |
6961c906 |
1590 | You should now be able to access the L<http://localhost:3000/books/list> |
1591 | URL as before. |
3533daff |
1592 | |
a8f4e284 |
1593 | B<NOTE:> Please note that if you use the default template technique, you |
1594 | will B<not> be able to use either the C<$c-E<gt>forward> or the |
1595 | C<$c-E<gt>detach> mechanisms (these are discussed in Chapter 2 and |
4b4d3884 |
1596 | Chapter 9 of the Tutorial). |
3533daff |
1597 | |
3b1fa91b |
1598 | B<IMPORTANT:> Make sure that you do NOT skip the following section |
1599 | before continuing to the next chapter 4 Basic CRUD. |
3533daff |
1600 | |
fce83e5f |
1601 | |
4d63a0d5 |
1602 | =head2 Return To A Manually Specified Template |
3533daff |
1603 | |
1604 | In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach> |
a8f4e284 |
1605 | later in the tutorial, you should remove the comment from the statement |
1606 | in C<sub list> in C<lib/MyApp/Controller/Books.pm>: |
3533daff |
1607 | |
0ed3df53 |
1608 | $c->stash(template => 'books/list.tt2'); |
3533daff |
1609 | |
a8f4e284 |
1610 | Then delete the C<TEMPLATE_EXTENSION> line in C<lib/MyApp/View/HTML.pm>. |
3533daff |
1611 | |
a8f4e284 |
1612 | Check the L<http://localhost:3000/books/list> URL in your browser. It |
1613 | should look the same manner as with earlier sections. |
3533daff |
1614 | |
1615 | |
1616 | =head1 AUTHOR |
1617 | |
1618 | Kennedy Clark, C<hkclark@gmail.com> |
1619 | |
53243324 |
1620 | Feel free to contact the author for any errors or suggestions, but the |
1621 | best way to report issues is via the CPAN RT Bug system at |
1622 | <https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>. |
1623 | |
1624 | The most recent version of the Catalyst Tutorial can be found at |
59884771 |
1625 | L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>. |
3533daff |
1626 | |
ec3ef4ad |
1627 | Copyright 2006-2010, Kennedy Clark, under the |
1628 | Creative Commons Attribution Share-Alike License Version 3.0 |
8482d557 |
1629 | (L<http://creativecommons.org/licenses/by-sa/3.0/us/>). |