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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 |
65 | virtually 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 |
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72 | L<Catalyst::Manual::Tutorial::01_Intro/CATALYST INSTALLATION> before |
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73 | doing the rest of this tutorial. Although the tutorial should work |
74 | correctly under most any recent version of Perl running on any |
75 | operating system, the tutorial has been written using Debian 5 and |
76 | tested to be sure it runs correctly in this environment. |
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 |
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99 | C<Hello> and C<hello>. (As noted in Chapter 2, omit the ".pl" from |
100 | the command if you are using Strawberry Perl.) |
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101 | |
102 | |
103 | =head1 EDIT THE LIST OF CATALYST PLUGINS |
104 | |
105 | One of the greatest benefits of Catalyst is that it has such a large |
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106 | library of plugins and base classes available. Plugins are used to |
107 | seamlessly integrate existing Perl modules into the overall Catalyst |
108 | framework. In general, they do this by adding additional methods to the |
109 | C<context> object (generally written as C<$c>) that Catalyst passes to |
110 | every component throughout the framework. |
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111 | |
112 | By default, Catalyst enables three plugins/flags: |
113 | |
114 | =over 4 |
115 | |
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116 | =item * |
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117 | |
118 | C<-Debug> Flag |
119 | |
120 | Enables the Catalyst debug output you saw when we started the |
121 | C<script/myapp_server.pl> development server earlier. You can remove |
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122 | this item when you place your application into production. |
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123 | |
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124 | To be technically correct, it turns out that C<-Debug> is not a plugin, but a I<flag>. |
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125 | Although most of the items specified on the C<__PACKAGE__-E<gt>setup> |
126 | line of your application class will be plugins, Catalyst supports a |
127 | limited number of flag options (of these, C<-Debug> is the most |
128 | common). See the documentation for C<Catalyst.pm> to get details on |
129 | other flags (currently C<-Engine>, C<-Home>, and C<-Log>). |
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130 | |
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131 | If you prefer, there are several other ways to enable debug output: |
132 | |
133 | =over 4 |
134 | |
135 | =item * |
136 | |
137 | Use the C<$c-E<gt>debug> method |
138 | |
139 | =item * |
140 | |
141 | The C<-d> option to C<script/myapp_server.pl> |
142 | |
143 | =item * |
144 | |
145 | The C<CATALYST_DEBUG=1> environment variable (or set it to |
146 | zero to templorarily disable debug output). |
147 | |
148 | =back |
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149 | |
150 | B<TIP>: Depending on your needs, it can be helpful to permanently |
151 | remove C<-Debug> from C<lib/MyApp.pm> and then use the C<-d> option |
152 | to C<script/myapp_server.pl> to re-enable it just for the development |
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153 | server. We will not be using that approach in the tutorial, but feel |
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154 | free to make use of it in your own projects. |
155 | |
156 | =item * |
157 | |
158 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> |
159 | |
160 | C<ConfigLoader> provides an automatic way to load configurable |
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161 | parameters for your application from a central |
162 | L<Config::General|Config::General> file (versus having the values |
163 | hard-coded inside your Perl modules). Config::General uses syntax |
164 | very similar to Apache configuration files. We will see how to use |
165 | this feature of Catalyst during the authentication and authorization |
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166 | sections (Chapter 5 and Chapter 6). |
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167 | |
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168 | B<IMPORTANT NOTE:> If you are using a version of |
169 | L<Catalyst::Devel|Catalyst::Devel> prior to version 1.06, be aware |
170 | that Catalyst changed the default format from YAML to the more |
171 | straightforward C<Config::General> style. This tutorial uses the |
172 | newer C<myapp.conf> file for C<Config::General>. However, Catalyst |
173 | supports both formats and will automatically use either C<myapp.conf> |
174 | or C<myapp.yml> (or any other format supported by |
175 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> and |
176 | L<Config::Any|Config::Any>). If you are using a version of |
177 | Catalyst::Devel prior to 1.06, you can convert to the newer format by |
178 | simply creating the C<myapp.conf> file manually and deleting |
179 | C<myapp.yml>. The default contents of the C<myapp.conf> you create |
180 | should only consist of one line: |
181 | |
182 | name MyApp |
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183 | |
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184 | B<TIP>: This script can be useful for converting between configuration |
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185 | formats: |
186 | |
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187 | perl -Ilib -e 'use MyApp; use Config::General; |
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188 | Config::General->new->save_file("myapp.conf", MyApp->config);' |
189 | |
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190 | =item * |
191 | |
192 | L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple> |
193 | |
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194 | C<Static::Simple> provides an easy way to serve static content, such |
195 | as images and CSS files, from the development server. |
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196 | |
197 | =back |
198 | |
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199 | For our application, we want to add one new plugin into the mix. To |
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200 | do this, edit C<lib/MyApp.pm> (this file is generally referred to as |
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201 | your I<application class>) and delete the lines with: |
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202 | |
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203 | use Catalyst qw/ |
204 | -Debug |
205 | ConfigLoader |
206 | Static::Simple |
207 | /; |
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208 | |
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209 | Then replace it with: |
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210 | |
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211 | # Load plugins |
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212 | use Catalyst qw/ |
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213 | -Debug |
214 | ConfigLoader |
215 | Static::Simple |
216 | |
217 | StackTrace |
218 | /; |
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219 | |
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220 | B<Note:> Recent versions of C<Catalyst::Devel> have used a variety of |
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221 | techniques to load these plugins/flags. For example, you might see |
222 | the following: |
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223 | |
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224 | __PACKAGE__->setup(qw/-Debug ConfigLoader Static::Simple/); |
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225 | |
226 | Don't let these variations confuse you -- they all accomplish the same |
227 | result. |
228 | |
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229 | This tells Catalyst to start using one new plugin, |
230 | L<Catalyst::Plugin::StackTrace|Catalyst::Plugin::StackTrace>, to add a |
231 | stack trace to the standard Catalyst "debug screen" (the screen |
232 | Catalyst sends to your browser when an error occurs). Be aware that |
233 | L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your |
234 | browser, not in the console window from which you're running your |
235 | application, which is where logging output usually goes. |
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236 | |
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237 | Make sure when adding new plugins you also include them as a new |
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238 | dependency within the Makefile.PL file. For example, after adding |
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239 | the StackTrace plugin the Makefile.PL should include the following |
240 | line: |
241 | |
242 | requires 'Catalyst::Plugin::StackTrace'; |
243 | |
244 | |
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245 | B<Notes:> |
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246 | |
247 | =over 4 |
248 | |
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249 | =item * |
250 | |
251 | C<__PACKAGE__> is just a shorthand way of referencing the name of the |
252 | package where it is used. Therefore, in C<MyApp.pm>, C<__PACKAGE__> |
253 | is equivalent to C<MyApp>. |
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254 | |
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255 | =item * |
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256 | |
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257 | You will want to disable L<StackTrace|Catalyst::Plugin::StackTrace> |
258 | before you put your application into production, but it can be helpful |
259 | during development. |
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260 | |
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261 | =item * |
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262 | |
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263 | When specifying plugins, you can omit C<Catalyst::Plugin::> from the |
264 | name. Additionally, you can spread the plugin names across multiple |
265 | lines as shown here or place them all on one line. |
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266 | |
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267 | =back |
268 | |
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269 | |
270 | =head1 CREATE A CATALYST CONTROLLER |
271 | |
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272 | As discussed earlier, controllers are where you write methods that |
273 | interact with user input. Typically, controller methods respond to |
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274 | C<GET> and C<POST> requests from the user's web browser. |
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275 | |
276 | Use the Catalyst C<create> script to add a controller for book-related |
277 | actions: |
278 | |
279 | $ script/myapp_create.pl controller Books |
280 | exists "/home/me/MyApp/script/../lib/MyApp/Controller" |
281 | exists "/home/me/MyApp/script/../t" |
282 | created "/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm" |
283 | created "/home/me/MyApp/script/../t/controller_Books.t" |
284 | |
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285 | Then edit C<lib/MyApp/Controller/Books.pm> (as discussed in Chapter 2 of |
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286 | the Tutorial, Catalyst has a separate directory under C<lib/MyApp> for |
287 | each of the three parts of MVC: C<Model>, C<View>, and C<Controller>) |
288 | and add the following method to the controller: |
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289 | |
290 | =head2 list |
291 | |
292 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
293 | |
294 | =cut |
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295 | |
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296 | sub list : Local { |
297 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
298 | # 'Context' that's used to 'glue together' the various components |
299 | # that make up the application |
300 | my ($self, $c) = @_; |
301 | |
302 | # Retrieve all of the book records as book model objects and store in the |
303 | # stash where they can be accessed by the TT template |
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304 | # $c->stash->{books} = [$c->model('DB::Book')->all]; |
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305 | # But, for now, use this code until we create the model later |
306 | $c->stash->{books} = ''; |
307 | |
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308 | # Set the TT template to use. You will almost always want to do this |
309 | # in your action methods (action methods respond to user input in |
310 | # your controllers). |
311 | $c->stash->{template} = 'books/list.tt2'; |
312 | } |
313 | |
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314 | B<TIP>: See Appendix 1 for tips on removing the leading spaces when |
315 | cutting and pasting example code from POD-based documents. |
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316 | |
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317 | Programmers experienced with object-oriented Perl should recognize |
318 | C<$self> as a reference to the object where this method was called. |
319 | On the other hand, C<$c> will be new to many Perl programmers who have |
320 | not used Catalyst before (it's sometimes written as C<$context>). The |
321 | Context object is automatically passed to all Catalyst components. It |
322 | is used to pass information between components and provide access to |
323 | Catalyst and plugin functionality. |
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324 | |
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325 | Catalyst actions are regular Perl methods, but they make use of |
326 | attributes (the "C<: Local>" next to the "C<sub list>" in the code |
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327 | above) to provide additional information to the Catalyst dispatcher |
328 | logic (note that the space between the colon and the attribute name is |
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329 | optional; you will see attributes written both ways). Most Catalyst |
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330 | Controllers use one of five action types: |
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331 | |
332 | =over 4 |
333 | |
334 | =item * |
335 | |
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336 | B<:Private> -- Use C<:Private> for methods that you want to make into |
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337 | an action, but you do not want Catalyst to directly expose the method |
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338 | to your users. Catalyst will not map C<:Private> methods to a URI. |
339 | Use them for various sorts of "special" methods (the C<begin>, |
340 | C<auto>, etc. discussed below) or for methods you want to be able to |
341 | C<forward> or C<detach> to. (If the method is a plain old "helper |
342 | method" that you don't want to be an action at all, then just define |
343 | the method without any attribute -- you can call it in your code, but |
344 | the Catalyst dispatcher will ignore it.) |
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345 | |
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346 | There are five types of "special" build-in C<:Private> actions: |
347 | C<begin>, C<end>, C<default>, C<index>, and C<auto>. |
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348 | |
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349 | =over 4 |
350 | |
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351 | =item * |
352 | |
353 | With C<begin>, C<end>, C<default>, C<index> private actions, only the |
354 | most specific action of each type will be called. For example, if you |
355 | define a C<begin> action in your controller it will I<override> a |
356 | C<begin> action in your application/root controller -- I<only> the |
357 | action in your controller will be called. |
358 | |
359 | =item * |
360 | |
361 | Unlike the other actions where only a single method is called for each |
362 | request, I<every> auto action along the chain of namespaces will be |
363 | called. Each C<auto> action will be called I<from the application/root |
364 | controller down through the most specific class>. |
365 | |
366 | =back |
367 | |
368 | =item * |
369 | |
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370 | B<:Path> -- C<:Path> actions let you map a method to an explicit URI |
371 | path. For example, "C<:Path('list')>" in |
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372 | C<lib/MyApp/Controller/Books.pm> would match on the URL |
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373 | C<http://localhost:3000/books/list>, but "C<:Path('/list')>" would |
374 | match on C<http://localhost:3000/list> (because of the leading slash). |
375 | You can use C<:Args()> to specify how many arguments an action should |
376 | accept. See L<Catalyst::Manual::Intro/Action_types> for more |
377 | information and examples. |
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378 | |
379 | =item * |
380 | |
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381 | B<:Local> -- C<:Local> is merely a shorthand for |
382 | "C<:Path('_name_of_method_')>". For example, these are equivalent: |
383 | "C<sub create_book :Local {...}>" and |
384 | "C<sub create_book :Path('create_book') {...}>". |
385 | |
386 | =item * |
387 | |
388 | B<:Global> -- C<:Global> is merely a shorthand for |
389 | "C<:Path('/_name_of_method_')>". For example, these are equivalent: |
390 | "C<sub create_book :Global {...}>" and |
391 | "C<sub create_book :Path('/create_book') {...}>". |
392 | |
393 | =item * |
394 | |
395 | B<:Chained> -- Newer Catalyst applications tend to use the Chained |
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396 | dispatch form of action types because of its power and flexibility. |
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397 | It allows a series of controller methods to be automatically dispatched |
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398 | to service a single user request. See |
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399 | L<Catalyst::Manual::Tutorial::04_BasicCRUD|Catalyst::Manual::Tutorial::04_BasicCRUD> |
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400 | and L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained> |
401 | for more information on chained actions. |
402 | |
403 | =back |
404 | |
405 | You should refer to L<Catalyst::Manual::Intro/Action_types> for |
406 | additional information and for coverage of some lesser-used action |
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407 | types not discussed here (C<Regex> and C<LocalRegex>). |
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408 | |
409 | |
410 | =head1 CATALYST VIEWS |
411 | |
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412 | As mentioned in Chapter 2 of the tutorial, views are where you render |
413 | output, typically for display in the user's web browser (but also |
414 | possibly using into output-generation systems, such as PDF or JSON). |
415 | The code in C<lib/MyApp/View> selects the I<type> of view to use, with |
416 | the actual rendering template found in the C<root> directory. As with |
417 | virtually every aspect of Catalyst, options abound when it comes to the |
418 | specific view technology you adopt inside your application. However, |
419 | most Catalyst applications use the Template Toolkit, known as TT (for |
420 | more information on TT, see L<http://www.template-toolkit.org>). Other |
421 | somewhat popular view technologies include Mason |
422 | (L<http://www.masonhq.com> and L<http://www.masonbook.com>) and |
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423 | L<HTML::Template> (L<http://html-template.sourceforge.net>). |
424 | |
425 | |
426 | =head2 Create a Catalyst View |
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427 | |
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428 | When using TT for the Catalyst view, the main helper script |
429 | is L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT>. |
430 | You may also come across references to |
431 | L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite>, |
432 | but its use is now deprecated. |
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433 | |
434 | Enter the following command to enable the C<TT> style of view |
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435 | rendering for this tutorial: |
436 | |
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437 | $ script/myapp_create.pl view TT TT |
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438 | exists "/home/me/MyApp/script/../lib/MyApp/View" |
439 | exists "/home/me/MyApp/script/../t" |
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440 | created "/home/me/MyApp/script/../lib/MyApp/View/TT.pm" |
441 | created "/home/me/MyApp/script/../t/view_TT.t" |
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442 | |
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443 | This simply creates a view called C<TT> (the second 'TT' argument) in |
444 | a file called C<TT.pm> (the first 'TT' argument). It is now up to you |
445 | to decide how you want to structure your view layout. For the |
446 | tutorial, we will start with a very simple TT template to initially |
447 | demonstrate the concepts, but quickly migrate to a more typical |
448 | "wrapper page" type of configuration (where the "wrapper" controls the |
449 | overall "look and feel" of your site from a single file or set of |
450 | files). |
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451 | |
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452 | Edit C<lib/MyApp/View/TT.pm> and you should see that the default |
453 | contents contains something similar to the following: |
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454 | |
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455 | __PACKAGE__->config(TEMPLATE_EXTENSION => '.tt'); |
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456 | |
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457 | And update it to match: |
458 | |
459 | __PACKAGE__->config( |
460 | # Change default TT extension |
461 | TEMPLATE_EXTENSION => '.tt2', |
462 | # Set the location for TT files |
463 | INCLUDE_PATH => [ |
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464 | MyApp->path_to( 'root', 'src' ), |
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465 | ], |
466 | ); |
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467 | |
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468 | B<NOTE:> Make sure to add a comma after '.tt2' outside the single |
469 | quote. |
470 | |
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471 | This changes the default extension for Template Toolkit from '.tt' to |
472 | '.tt2' and changes the base directory for your template files from |
473 | C<root> to C<root/src>. Stick with these conventions for the |
474 | tutorial, but feel free to use whatever options you desire in your |
475 | applications (as with most things Perl, there's more than one way to |
476 | do it...). |
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477 | |
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478 | B<Note:> We will use C<root/src> as the base directory for our |
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479 | template files, with a full naming convention of |
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480 | C<root/src/_controller_name_/_action_name_.tt2>. Another popular option is to |
481 | use C<root/> as the base (with a full filename pattern of |
482 | C<root/_controller_name_/_action_name_.tt2>). |
483 | |
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484 | |
485 | =head2 Create a TT Template Page |
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486 | |
487 | First create a directory for book-related TT templates: |
488 | |
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489 | $ mkdir -p root/src/books |
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490 | |
491 | Then create C<root/src/books/list.tt2> in your editor and enter: |
492 | |
493 | [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%] |
494 | [% # see this "chomping" in your browser because HTML ignores blank lines, but -%] |
495 | [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%] |
496 | [%- # optional, but both the beginning and the ending TT tags support chomping. -%] |
497 | |
1390ef0e |
498 | [% # Provide a title -%] |
3533daff |
499 | [% META title = 'Book List' -%] |
500 | |
501 | <table> |
502 | <tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr> |
503 | [% # Display each book in a table row %] |
504 | [% FOREACH book IN books -%] |
505 | <tr> |
506 | <td>[% book.title %]</td> |
507 | <td>[% book.rating %]</td> |
a46b474e |
508 | <td></td> |
3533daff |
509 | </tr> |
510 | [% END -%] |
511 | </table> |
512 | |
513 | As indicated by the inline comments above, the C<META title> line uses |
1390ef0e |
514 | TT's META feature to provide a title to the "wrapper" that we will |
515 | create later. Meanwhile, the C<FOREACH> loop iterates through each |
516 | C<book> model object and prints the C<title> and C<rating> fields. |
3533daff |
517 | |
4d63a0d5 |
518 | The C<[%> and C<%]> tags are used to delimit Template Toolkit code. TT |
519 | supports a wide variety of directives for "calling" other files, |
520 | looping, conditional logic, etc. In general, TT simplifies the usual |
444d6b27 |
521 | range of Perl operators down to the single dot (".") operator. This |
4d63a0d5 |
522 | applies to operations as diverse as method calls, hash lookups, and list |
523 | index values (see |
524 | L<http://search.cpan.org/perldoc?Template::Manual::Variables> for |
444d6b27 |
525 | details and examples). In addition to the usual L<Template> module Pod |
4d63a0d5 |
526 | documentation, you can access the TT manual at |
55beb65d |
527 | L<http://search.cpan.org/perldoc?Template::Manual>. |
3533daff |
528 | |
444d6b27 |
529 | B<TIP:> While you can build all sorts of complex logic into your TT |
530 | templates, you should in general keep the "code" part of your |
531 | templates as simple as possible. If you need more complex logic, |
532 | create helper methods in your model that abstract out a set of code |
533 | into a single call from your TT template. (Note that the same is true |
534 | of your controller logic as well -- complex sections of code in your |
535 | controllers should often be pulled out and placed into your model |
536 | objects.) In Chapter 4 of the tutorial we will explore some extremely |
537 | helpful and powerful features of L<DBIx::Class> that allow you to pull |
538 | code out of your views and controllers and place it where it |
539 | rightfully belongs in a model class. |
1390ef0e |
540 | |
541 | |
542 | =head2 Test Run The Application |
543 | |
544 | To test your work so far, first start the development server: |
545 | |
546 | $ script/myapp_server.pl |
547 | |
548 | Then point your browser to L<http://localhost:3000> and you should |
549 | still get the Catalyst welcome page. Next, change the URL in your |
550 | browser to L<http://localhost:3000/books/list>. If you have |
551 | everything working so far, you should see a web page that displays |
552 | nothing other than our column headers for "Title", "Rating", and |
553 | "Author(s)" -- we will not see any books until we get the database and |
554 | model working below. |
555 | |
556 | If you run into problems getting your application to run correctly, it |
557 | might be helpful to refer to some of the debugging techniques covered in |
fce83e5f |
558 | the L<Debugging|Catalyst::Manual::Tutorial::07_Debugging> chapter of the |
1390ef0e |
559 | tutorial. |
3533daff |
560 | |
561 | |
562 | =head1 CREATE A SQLITE DATABASE |
563 | |
564 | In this step, we make a text file with the required SQL commands to |
429e7843 |
565 | create a database table and load some sample data. We will use |
9887a877 |
566 | SQLite (L<http://www.sqlite.org>), a popular database that is |
429e7843 |
567 | lightweight and easy to use. Be sure to get at least version 3. Open |
1390ef0e |
568 | C<myapp01.sql> in your editor and enter: |
3533daff |
569 | |
570 | -- |
571 | -- Create a very simple database to hold book and author information |
572 | -- |
3b1fa91b |
573 | CREATE TABLE book ( |
3533daff |
574 | id INTEGER PRIMARY KEY, |
575 | title TEXT , |
576 | rating INTEGER |
577 | ); |
3b1fa91b |
578 | -- 'book_author' is a many-to-many join table between books & authors |
579 | CREATE TABLE book_author ( |
b66dd084 |
580 | book_id INTEGER REFERENCES book(id) ON DELETE CASCADE ON UPDATE CASCADE, |
581 | author_id INTEGER REFERENCES author(id) ON DELETE CASCADE ON UPDATE CASCADE, |
3533daff |
582 | PRIMARY KEY (book_id, author_id) |
583 | ); |
3b1fa91b |
584 | CREATE TABLE author ( |
3533daff |
585 | id INTEGER PRIMARY KEY, |
586 | first_name TEXT, |
587 | last_name TEXT |
588 | ); |
589 | --- |
590 | --- Load some sample data |
591 | --- |
3b1fa91b |
592 | INSERT INTO book VALUES (1, 'CCSP SNRS Exam Certification Guide', 5); |
593 | INSERT INTO book VALUES (2, 'TCP/IP Illustrated, Volume 1', 5); |
594 | INSERT INTO book VALUES (3, 'Internetworking with TCP/IP Vol.1', 4); |
595 | INSERT INTO book VALUES (4, 'Perl Cookbook', 5); |
596 | INSERT INTO book VALUES (5, 'Designing with Web Standards', 5); |
597 | INSERT INTO author VALUES (1, 'Greg', 'Bastien'); |
598 | INSERT INTO author VALUES (2, 'Sara', 'Nasseh'); |
599 | INSERT INTO author VALUES (3, 'Christian', 'Degu'); |
600 | INSERT INTO author VALUES (4, 'Richard', 'Stevens'); |
601 | INSERT INTO author VALUES (5, 'Douglas', 'Comer'); |
602 | INSERT INTO author VALUES (6, 'Tom', 'Christiansen'); |
603 | INSERT INTO author VALUES (7, 'Nathan', 'Torkington'); |
604 | INSERT INTO author VALUES (8, 'Jeffrey', 'Zeldman'); |
605 | INSERT INTO book_author VALUES (1, 1); |
606 | INSERT INTO book_author VALUES (1, 2); |
607 | INSERT INTO book_author VALUES (1, 3); |
608 | INSERT INTO book_author VALUES (2, 4); |
609 | INSERT INTO book_author VALUES (3, 5); |
610 | INSERT INTO book_author VALUES (4, 6); |
611 | INSERT INTO book_author VALUES (4, 7); |
612 | INSERT INTO book_author VALUES (5, 8); |
3533daff |
613 | |
3533daff |
614 | Then use the following command to build a C<myapp.db> SQLite database: |
615 | |
616 | $ sqlite3 myapp.db < myapp01.sql |
617 | |
618 | If you need to create the database more than once, you probably want to |
619 | issue the C<rm myapp.db> command to delete the database before you use |
1390ef0e |
620 | the C<sqlite3 myapp.db E<lt> myapp01.sql> command. |
3533daff |
621 | |
622 | Once the C<myapp.db> database file has been created and initialized, you |
623 | can use the SQLite command line environment to do a quick dump of the |
624 | database contents: |
625 | |
626 | $ sqlite3 myapp.db |
acbd7bdd |
627 | SQLite version 3.5.9 |
3533daff |
628 | Enter ".help" for instructions |
3b1fa91b |
629 | sqlite> select * from book; |
3533daff |
630 | 1|CCSP SNRS Exam Certification Guide|5 |
631 | 2|TCP/IP Illustrated, Volume 1|5 |
632 | 3|Internetworking with TCP/IP Vol.1|4 |
633 | 4|Perl Cookbook|5 |
634 | 5|Designing with Web Standards|5 |
635 | sqlite> .q |
636 | $ |
637 | |
638 | Or: |
639 | |
3b1fa91b |
640 | $ sqlite3 myapp.db "select * from book" |
3533daff |
641 | 1|CCSP SNRS Exam Certification Guide|5 |
642 | 2|TCP/IP Illustrated, Volume 1|5 |
643 | 3|Internetworking with TCP/IP Vol.1|4 |
644 | 4|Perl Cookbook|5 |
645 | 5|Designing with Web Standards|5 |
646 | |
647 | As with most other SQL tools, if you are using the full "interactive" |
648 | environment you need to terminate your SQL commands with a ";" (it's not |
649 | required if you do a single SQL statement on the command line). Use |
650 | ".q" to exit from SQLite from the SQLite interactive mode and return to |
651 | your OS command prompt. |
652 | |
b66dd084 |
653 | Please note that here we have chosen to use 'singular' table names. This is |
e586b5f4 |
654 | because the default inflection code for older versions of |
b66dd084 |
655 | L<DBIx::Class::Schema::Loader> does NOT handle plurals. There has been much |
656 | philosophical discussion on whether table names should be plural or singular. |
657 | There is no one correct answer, as long as one makes a choice and remains |
658b8c29 |
658 | consistent with it. If you prefer plural table names (e.g. you think that they |
659 | are easier to read) then see the documentation in |
660 | L<DBIx::Class::Schema::Loader::Base/naming> (version 0.05 or greater). |
3b1fa91b |
661 | |
a6d800ac |
662 | For using other databases, such as PostgreSQL or MySQL, see |
3ab6187c |
663 | L<Appendix 2|Catalyst::Manual::Tutorial::10_Appendices>. |
3533daff |
664 | |
acbd7bdd |
665 | |
8a472b34 |
666 | =head1 DATABASE ACCESS WITH DBIx::Class |
3533daff |
667 | |
27909ed4 |
668 | Catalyst can be used with virtually any form of datastore available |
669 | via Perl. For example, L<Catalyst::Model::DBI|Catalyst::Model::DBI> |
444d6b27 |
670 | can be used to access databases through the traditional Perl L<DBI> |
27909ed4 |
671 | interface or you can use a model to access files of any type on the |
672 | filesystem. However, most Catalyst applications use some form of |
673 | object-relational mapping (ORM) technology to create objects |
674 | associated with tables in a relational database. Matt Trout's |
675 | L<DBIx::Class|DBIx::Class> (abbreviated as "DBIC") has rapidly emerged |
676 | as the Perl-based ORM technology of choice. Most new Catalyst |
a46b474e |
677 | applications rely on DBIx::Class, as will this tutorial. |
3533daff |
678 | |
a46b474e |
679 | Although DBIx::Class has included support for a C<create=dynamic> mode |
680 | to automatically read the database structure every time the |
681 | application starts, it's use is no longer recommended. While it can |
682 | make for "flashy" demos, the use of the C<create=static> mode we use |
683 | below can be implemented just as quickly and provides many advantages |
684 | (such as the ability to add your own methods to the overall DBIC |
685 | framework, a technique that we see in Chapter 4). |
3533daff |
686 | |
1390ef0e |
687 | |
a46b474e |
688 | =head2 Make Sure You Have a Recent Version of the DBIx::Class Model |
27909ed4 |
689 | |
690 | First, let's be sure we have a recent version of the DBIC helper, |
691 | L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>, by |
692 | running this command: |
693 | |
694 | $ perl -MCatalyst::Model::DBIC::Schema -e \ |
695 | 'print "$Catalyst::Model::DBIC::Schema::VERSION\n"' |
a467a714 |
696 | 0.31 |
27909ed4 |
697 | |
fce83e5f |
698 | Please note the '\' above. Depending on your environment, you might |
699 | be able to cut and paste the text as shown or need to remove the '\' |
700 | character to that the command is all on a single line. |
3b1fa91b |
701 | |
a467a714 |
702 | You should have version 0.31 or greater if you are following along |
444d6b27 |
703 | with Debian 5. In other environments, you may need to run this |
704 | command to install it directly from CPAN: |
27909ed4 |
705 | |
706 | $ sudo cpan Catalyst::Model::DBIC::Schema |
707 | |
708 | And re-run the version print command to verify that you are now at |
a467a714 |
709 | 0.31 or higher. |
27909ed4 |
710 | |
b66dd084 |
711 | Please use version C<1.27> of L<DBD::SQLite> or later for proper foreign key |
712 | support. |
27909ed4 |
713 | |
a46b474e |
714 | =head2 Create Static DBIx::Class Schema Files |
27909ed4 |
715 | |
98fd8420 |
716 | Before you continue, make sure your C<myapp.db> database file is in |
717 | the application's topmost directory. Now use the model helper with |
718 | the C<create=static> option to read the database with |
27909ed4 |
719 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> and |
720 | automatically build the required files for us: |
3533daff |
721 | |
4ab6212d |
722 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \ |
b66dd084 |
723 | create=static dbi:SQLite:myapp.db \ |
724 | on_connect_do="PRAGMA foreign_keys = ON" |
1390ef0e |
725 | exists "/home/me/MyApp/script/../lib/MyApp/Model" |
726 | exists "/home/me/MyApp/script/../t" |
27909ed4 |
727 | Dumping manual schema for MyApp::Schema to directory /home/me/MyApp/script/../lib ... |
728 | Schema dump completed. |
1390ef0e |
729 | created "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm" |
730 | created "/home/me/MyApp/script/../t/model_DB.t" |
3533daff |
731 | |
fce83e5f |
732 | Please note the '\' above. Depending on your environment, you might |
733 | be able to cut and paste the text as shown or need to remove the '\' |
734 | character to that the command is all on a single line. |
3b1fa91b |
735 | |
27909ed4 |
736 | The C<script/myapp_create.pl> command breaks down like this: |
737 | |
738 | =over 4 |
739 | |
740 | =item * |
741 | |
742 | C<DB> is the name of the model class to be created by the helper in |
743 | C<lib/MyApp/Model>. |
744 | |
745 | =item * |
746 | |
747 | C<DBIC::Schema> is the type of the model to create. |
748 | |
749 | =item * |
750 | |
751 | C<MyApp::Schema> is the name of the DBIC schema file written to |
752 | C<lib/MyApp/Schema.pm>. |
753 | |
754 | =item * |
755 | |
756 | C<create=static> causes |
757 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to |
758 | load the schema as it runs and then write that information out |
759 | into files. |
760 | |
761 | =item * |
762 | |
27909ed4 |
763 | And finally, C<dbi:SQLite:myapp.db> is the standard DBI connect string |
764 | for use with SQLite. |
765 | |
766 | =back |
767 | |
768 | If you look in the C<lib/MyApp/Schema.pm> file, you will find that it |
769 | only contains a call to the C<load_namespaces> method. You will also |
770 | find that C<lib/MyApp> contains a C<Schema> subdirectory, which then |
771 | has a subdirectory called "Result". This "Result" subdirectory then |
772 | has files named according to each of the tables in our simple database |
3b1fa91b |
773 | (C<Author.pm>, C<BookAuthor.pm>, and C<Book.pm>). These three |
a46b474e |
774 | files are called "Result Classes" in DBIx::Class nomenclature. Although the |
27909ed4 |
775 | Result Class files are named after tables in our database, the classes |
776 | correspond to the I<row-level data> that is returned by DBIC (more on |
777 | this later, especially in |
3ab6187c |
778 | L<Catalyst::Manual::Tutorial::04_BasicCRUD/EXPLORING THE POWER OF DBIC>). |
27909ed4 |
779 | |
780 | The idea with the Result Source files created under |
781 | C<lib/MyApp/Schema/Result> by the C<create=static> option is to only |
782 | edit the files below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> |
783 | warning. If you place all of your changes below that point in the |
784 | file, you can regenerate the automatically created information at the |
785 | top of each file should your database structure get updated. |
786 | |
787 | Also note the "flow" of the model information across the various files |
788 | and directories. Catalyst will initially load the model from |
789 | C<lib/MyApp/Model/DB.pm>. This file contains a reference to |
790 | C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, the |
791 | call to C<load_namespaces> in C<Schema.pm> will load each of the |
792 | "Result Class" files from the C<lib/MyApp/Schema/Result> subdirectory. |
793 | The final outcome is that Catalyst will dynamically create three |
794 | table-specific Catalyst models every time the application starts (you |
795 | can see these three model files listed in the debug output generated |
796 | when you launch the application). |
797 | |
798 | B<NOTE:> Older versions of |
799 | L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> use the |
a46b474e |
800 | deprecated DBIx::Class C<load_classes> technique instead of the newer |
27909ed4 |
801 | C<load_namspaces>. For new applications, please try to use |
802 | C<load_namespaces> since it more easily supports a very useful DBIC |
803 | technique called "ResultSet Classes." If you need to convert an |
804 | existing application from "load_classes" to "load_namespaces," you can |
b66dd084 |
805 | use this process to automate the migration, but first make sure you have |
806 | version C<0.39> of L<Catalyst::Model::DBIC::Schema> and |
807 | L<DBIx::Class::Schema::Loader> version C<0.05000> or later. |
27909ed4 |
808 | |
b66dd084 |
809 | $ # Re-run the helper to upgrade for you |
27909ed4 |
810 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \ |
b66dd084 |
811 | create=static naming=current use_namespaces=1 \ |
812 | dbi:SQLite:myapp.db \ |
813 | on_connect_do="PRAGMA foreign_keys = ON" |
dc9a0503 |
814 | |
1390ef0e |
815 | =head1 ENABLE THE MODEL IN THE CONTROLLER |
816 | |
acbd7bdd |
817 | Open C<lib/MyApp/Controller/Books.pm> and un-comment the model code we |
818 | left disabled earlier so that your version matches the following (un- |
3b1fa91b |
819 | comment the line containing C<[$c-E<gt>model('DB::Book')-E<gt>all]> |
acbd7bdd |
820 | and delete the next 2 lines): |
1390ef0e |
821 | |
822 | =head2 list |
823 | |
824 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
825 | |
826 | =cut |
827 | |
828 | sub list : Local { |
829 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
830 | # 'Context' that's used to 'glue together' the various components |
831 | # that make up the application |
832 | my ($self, $c) = @_; |
833 | |
834 | # Retrieve all of the book records as book model objects and store in the |
835 | # stash where they can be accessed by the TT template |
3b1fa91b |
836 | $c->stash->{books} = [$c->model('DB::Book')->all]; |
1390ef0e |
837 | |
838 | # Set the TT template to use. You will almost always want to do this |
839 | # in your action methods (action methods respond to user input in |
840 | # your controllers). |
841 | $c->stash->{template} = 'books/list.tt2'; |
842 | } |
843 | |
3b1fa91b |
844 | B<TIP>: You may see the C<$c-E<gt>model('DB::Book')> un-commented |
845 | above written as C<$c-E<gt>model('DB')-E<gt>resultset('Book')>. The |
c93b5eaa |
846 | two are equivalent. Either way, C<$c-E<gt>model> returns a |
847 | L<DBIx::Class::ResultSet|DBIx::Class::ResultSet> which handles queries |
4d63a0d5 |
848 | against the database and iterating over the set of results that is |
c93b5eaa |
849 | returned. |
850 | |
851 | We are using the C<-E<gt>all> to fetch all of the books. DBIC |
852 | supports a wide variety of more advanced operations to easily do |
853 | things like filtering and sorting the results. For example, the |
518f3851 |
854 | following could be used to sort the results by descending title: |
c93b5eaa |
855 | |
3b1fa91b |
856 | $c->model('DB::Book')->search({}, {order_by => 'title DESC'}); |
c93b5eaa |
857 | |
858 | Some other examples are provided in |
859 | L<DBIx::Class::Manual::Cookbook/Complex WHERE clauses>, with |
860 | additional information found at L<DBIx::Class::ResultSet/search>, |
861 | L<DBIx::Class::Manual::FAQ/Searching>, |
862 | L<DBIx::Class::Manual::Intro|DBIx::Class::Manual::Intro> |
863 | and L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>. |
1390ef0e |
864 | |
865 | |
866 | =head2 Test Run The Application |
3533daff |
867 | |
1435672d |
868 | First, let's enable an environment variable that causes DBIx::Class to |
acbd7bdd |
869 | dump the SQL statements used to access the database. This is a |
1435672d |
870 | helpful trick when you are trying to debug your database-oriented |
871 | code: |
3533daff |
872 | |
873 | $ export DBIC_TRACE=1 |
874 | |
4d63a0d5 |
875 | This assumes you are using bash as your shell -- adjust accordingly if |
3533daff |
876 | you are using a different shell (for example, under tcsh, use |
877 | C<setenv DBIC_TRACE 1>). |
878 | |
d0496197 |
879 | B<NOTE:> You can also set this in your code using |
3533daff |
880 | C<$class-E<gt>storage-E<gt>debug(1);>. See |
881 | L<DBIx::Class::Manual::Troubleshooting> for details (including options |
4d63a0d5 |
882 | to log to a file instead of displaying to the Catalyst development server |
3533daff |
883 | log). |
884 | |
1390ef0e |
885 | Then launch the Catalyst development server. The log output should |
886 | display something like: |
3533daff |
887 | |
acbd7bdd |
888 | $ script/myapp_server.pl |
3533daff |
889 | [debug] Debug messages enabled |
1390ef0e |
890 | [debug] Statistics enabled |
3533daff |
891 | [debug] Loaded plugins: |
892 | .----------------------------------------------------------------------------. |
a467a714 |
893 | | Catalyst::Plugin::ConfigLoader 0.27 | |
894 | | Catalyst::Plugin::StackTrace 0.11 | |
895 | | Catalyst::Plugin::Static::Simple 0.25 | |
3533daff |
896 | '----------------------------------------------------------------------------' |
897 | |
898 | [debug] Loaded dispatcher "Catalyst::Dispatcher" |
899 | [debug] Loaded engine "Catalyst::Engine::HTTP" |
900 | [debug] Found home "/home/me/MyApp" |
45d511e0 |
901 | [debug] Loaded Config "/home/me/MyApp/myapp.conf" |
3533daff |
902 | [debug] Loaded components: |
903 | .-----------------------------------------------------------------+----------. |
904 | | Class | Type | |
905 | +-----------------------------------------------------------------+----------+ |
906 | | MyApp::Controller::Books | instance | |
907 | | MyApp::Controller::Root | instance | |
d0496197 |
908 | | MyApp::Model::DB | instance | |
3b1fa91b |
909 | | MyApp::Model::DB::Author | class | |
910 | | MyApp::Model::DB::Book | class | |
911 | | MyApp::Model::DB::BookAuthor | class | |
3533daff |
912 | | MyApp::View::TT | instance | |
913 | '-----------------------------------------------------------------+----------' |
914 | |
915 | [debug] Loaded Private actions: |
916 | .----------------------+--------------------------------------+--------------. |
917 | | Private | Class | Method | |
918 | +----------------------+--------------------------------------+--------------+ |
919 | | /default | MyApp::Controller::Root | default | |
920 | | /end | MyApp::Controller::Root | end | |
1390ef0e |
921 | | /index | MyApp::Controller::Root | index | |
3533daff |
922 | | /books/index | MyApp::Controller::Books | index | |
923 | | /books/list | MyApp::Controller::Books | list | |
924 | '----------------------+--------------------------------------+--------------' |
925 | |
926 | [debug] Loaded Path actions: |
927 | .-------------------------------------+--------------------------------------. |
928 | | Path | Private | |
929 | +-------------------------------------+--------------------------------------+ |
1390ef0e |
930 | | / | /default | |
931 | | / | /index | |
932 | | /books | /books/index | |
3533daff |
933 | | /books/list | /books/list | |
934 | '-------------------------------------+--------------------------------------' |
935 | |
a467a714 |
936 | [info] MyApp powered by Catalyst 5.80013 |
acbd7bdd |
937 | You can connect to your server at http://debian:3000 |
3533daff |
938 | |
1390ef0e |
939 | B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from |
940 | the 'base' directory of your application, not inside the C<script> |
941 | directory itself or it will not be able to locate the C<myapp.db> |
942 | database file. You can use a fully qualified or a relative path to |
943 | locate the database file, but we did not specify that when we ran the |
3533daff |
944 | model helper earlier. |
945 | |
946 | Some things you should note in the output above: |
947 | |
948 | =over 4 |
949 | |
1390ef0e |
950 | =item * |
3533daff |
951 | |
1390ef0e |
952 | Catalyst::Model::DBIC::Schema dynamically created three model classes, |
953 | one to represent each of the three tables in our database |
3b1fa91b |
954 | (C<MyApp::Model::DB::Author>, C<MyApp::Model::DB::BookAuthor>, |
955 | and C<MyApp::Model::DB::Book>). |
3533daff |
956 | |
1390ef0e |
957 | =item * |
3533daff |
958 | |
959 | The "list" action in our Books controller showed up with a path of |
960 | C</books/list>. |
961 | |
962 | =back |
963 | |
964 | Point your browser to L<http://localhost:3000> and you should still get |
965 | the Catalyst welcome page. |
966 | |
967 | Next, to view the book list, change the URL in your browser to |
968 | L<http://localhost:3000/books/list>. You should get a list of the five |
1390ef0e |
969 | books loaded by the C<myapp01.sql> script above without any formatting. |
970 | The rating for each book should appear on each row, but the "Author(s)" |
191dee29 |
971 | column will still be blank (we will fill that in later). |
3533daff |
972 | |
a46b474e |
973 | Also notice in the output of the C<script/myapp_server.pl> that |
974 | DBIx::Class used the following SQL to retrieve the data: |
3533daff |
975 | |
fce83e5f |
976 | SELECT me.id, me.title, me.rating FROM book me |
3533daff |
977 | |
978 | because we enabled DBIC_TRACE. |
979 | |
0c51850e |
980 | You now have the beginnings of a simple but workable web application. |
3533daff |
981 | Continue on to future sections and we will develop the application |
982 | more fully. |
983 | |
984 | |
1390ef0e |
985 | =head1 CREATE A WRAPPER FOR THE VIEW |
986 | |
acbd7bdd |
987 | When using TT, you can (and should) create a wrapper that will |
1390ef0e |
988 | literally wrap content around each of your templates. This is |
989 | certainly useful as you have one main source for changing things that |
990 | will appear across your entire site/application instead of having to |
991 | edit many individual files. |
992 | |
993 | |
994 | =head2 Configure TT.pm For The Wrapper |
995 | |
996 | In order to create a wrapper, you must first edit your TT view and |
444d6b27 |
997 | tell it where to find your wrapper file. |
1390ef0e |
998 | |
444d6b27 |
999 | Edit you TT view in C<lib/MyApp/View/TT.pm> and change it to match the |
1000 | following: |
1390ef0e |
1001 | |
1002 | __PACKAGE__->config( |
1003 | # Change default TT extension |
1004 | TEMPLATE_EXTENSION => '.tt2', |
1005 | # Set the location for TT files |
1006 | INCLUDE_PATH => [ |
c2dfb562 |
1007 | MyApp->path_to( 'root', 'src' ), |
1390ef0e |
1008 | ], |
1009 | # Set to 1 for detailed timer stats in your HTML as comments |
1010 | TIMER => 0, |
1011 | # This is your wrapper template located in the 'root/src' |
1012 | WRAPPER => 'wrapper.tt2', |
1013 | ); |
1014 | |
1015 | |
1016 | =head2 Create the Wrapper Template File and Stylesheet |
1017 | |
1018 | Next you need to set up your wrapper template. Basically, you'll want |
1019 | to take the overall layout of your site and put it into this file. |
1020 | For the tutorial, open C<root/src/wrapper.tt2> and input the following: |
1021 | |
1022 | <?xml version="1.0" encoding="UTF-8"?> |
1023 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> |
1024 | <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> |
1025 | <head> |
1026 | <title>[% template.title or "My Catalyst App!" %]</title> |
1027 | <link rel="stylesheet" href="[% c.uri_for('/static/css/main.css') %]" /> |
1028 | </head> |
1029 | |
1030 | <body> |
1031 | <div id="outer"> |
1032 | <div id="header"> |
1033 | [%# Your logo could go here -%] |
1034 | <img src="[% c.uri_for('/static/images/btn_88x31_powered.png') %]" /> |
1035 | [%# Insert the page title -%] |
1036 | <h1>[% template.title or site.title %]</h1> |
1037 | </div> |
1038 | |
1039 | <div id="bodyblock"> |
1040 | <div id="menu"> |
1041 | Navigation: |
1042 | <ul> |
1043 | <li><a href="[% c.uri_for('/books/list') %]">Home</a></li> |
1044 | <li><a href="[% c.uri_for('/') %]" title="Catalyst Welcome Page">Welcome</a></li> |
1390ef0e |
1045 | </ul> |
1046 | </div><!-- end menu --> |
1047 | |
1048 | <div id="content"> |
1049 | [%# Status and error messages %] |
1050 | <span class="message">[% status_msg %]</span> |
1051 | <span class="error">[% error_msg %]</span> |
1052 | [%# This is where TT will stick all of your template's contents. -%] |
1053 | [% content %] |
1054 | </div><!-- end content --> |
1055 | </div><!-- end bodyblock --> |
1056 | |
1057 | <div id="footer">Copyright (c) your name goes here</div> |
c2dfb562 |
1058 | </div><!-- end outer --> |
1390ef0e |
1059 | |
1060 | </body> |
1061 | </html> |
1062 | |
1063 | Notice the status and error message sections in the code above: |
1064 | |
1065 | <span class="status">[% status_msg %]</span> |
1066 | <span class="error">[% error_msg %]</span> |
1067 | |
1068 | If we set either message in the Catalyst stash (e.g., |
1069 | C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it |
1070 | will be displayed whenever any view used by that request is rendered. |
1071 | The C<message> and C<error> CSS styles can be customized to suit your |
1072 | needs in the C<root/static/css/main.css> file we create below. |
1073 | |
1074 | B<Notes:> |
1075 | |
1076 | =over 4 |
1077 | |
1078 | =item * |
1079 | |
1080 | The Catalyst stash only lasts for a single HTTP request. If |
1081 | you need to retain information across requests you can use |
1082 | L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use |
4b4d3884 |
1083 | Catalyst sessions in the Authentication chapter of the tutorial). |
1390ef0e |
1084 | |
1085 | =item * |
1086 | |
1087 | Although it is beyond the scope of this tutorial, you may wish to use |
1088 | a JavaScript or AJAX tool such as jQuery (L<http://www.jquery.com>) or |
1089 | Dojo (L<http://www.dojotoolkit.org>). |
1090 | |
1091 | =back |
1092 | |
1093 | |
1094 | =head3 Create A Basic Stylesheet |
1095 | |
1096 | First create a central location for stylesheets under the static |
1097 | directory: |
1098 | |
1099 | $ mkdir root/static/css |
1100 | |
1101 | Then open the file C<root/static/css/main.css> (the file referenced in |
1102 | the stylesheet href link of our wrapper above) and add the following |
1103 | content: |
1104 | |
1105 | #header { |
1106 | text-align: center; |
1107 | } |
1108 | #header h1 { |
1109 | margin: 0; |
1110 | } |
1111 | #header img { |
1112 | float: right; |
1113 | } |
1114 | #footer { |
1115 | text-align: center; |
1116 | font-style: italic; |
1117 | padding-top: 20px; |
1118 | } |
1119 | #menu { |
1120 | font-weight: bold; |
1121 | background-color: #ddd; |
1122 | } |
1123 | #menu ul { |
1124 | list-style: none; |
1125 | float: left; |
1126 | margin: 0; |
1127 | padding: 0 0 50% 5px; |
1128 | font-weight: normal; |
1129 | background-color: #ddd; |
1130 | width: 100px; |
1131 | } |
1132 | #content { |
1133 | margin-left: 120px; |
1134 | } |
1135 | .message { |
1136 | color: #390; |
1137 | } |
1138 | .error { |
1139 | color: #f00; |
1140 | } |
1141 | |
1142 | You may wish to check out a "CSS Framework" like Emastic |
1143 | (L<http://code.google.com/p/emastic/>) as a way to quickly |
1144 | provide lots of high-quality CSS functionality. |
1145 | |
1146 | |
1147 | =head2 Test Run The Application |
1148 | |
1149 | Restart the development server and hit "Reload" in your web browser |
1150 | and you should now see a formatted version of our basic book list. |
1151 | Although our wrapper and stylesheet are obviously very simple, you |
1152 | should see how it allows us to control the overall look of an entire |
1153 | website from two central files. To add new pages to the site, just |
1154 | provide a template that fills in the C<content> section of our wrapper |
1155 | template -- the wrapper will provide the overall feel of the page. |
1156 | |
1157 | |
a46b474e |
1158 | =head2 Updating the Generated DBIx::Class Result Class Files |
3533daff |
1159 | |
acbd7bdd |
1160 | Let's manually add some relationship information to the auto-generated |
b66dd084 |
1161 | Result Class files. C<many_to_many> relationships are not currently |
1162 | automatically generated by L<DBIx::Class::Schema::Loader>. |
1163 | First edit C<lib/MyApp/Schema/Result/Book.pm> and add the |
acbd7bdd |
1164 | following text below the C<# You can replace this text...> comment: |
3533daff |
1165 | |
3533daff |
1166 | # many_to_many(): |
1167 | # args: |
1168 | # 1) Name of relationship, DBIC will create accessor with this name |
1390ef0e |
1169 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
1170 | # 3) Name of belongs_to() relationship in model class of has_many() above |
3533daff |
1171 | # You must already have the has_many() defined to use a many_to_many(). |
fce83e5f |
1172 | __PACKAGE__->many_to_many(authors => 'book_authors', 'author'); |
3533daff |
1173 | |
3533daff |
1174 | B<Note:> Be careful to put this code I<above> the C<1;> at the end of the |
1175 | file. As with any Perl package, we need to end the last line with |
1176 | a statement that evaluates to C<true>. This is customarily done with |
1177 | C<1;> on a line by itself. |
1178 | |
b66dd084 |
1179 | You'll notice there is already a C<has_many> relationship called |
1180 | C<book_authors>. The C<many_to_many> relationship is optional, but it makes it |
1181 | easier to map a book to its collection of authors. Without |
3b1fa91b |
1182 | it, we would have to "walk" though the C<book_author> table as in |
1183 | C<$book-E<gt>book_author-E<gt>first-E<gt>author-E<gt>last_name> (we |
a46b474e |
1184 | will see examples on how to use DBIx::Class objects in your code soon, |
3b1fa91b |
1185 | but note that because C<$book-E<gt>book_author> can return multiple |
1390ef0e |
1186 | authors, we have to use C<first> to display a single author). |
5a82cb36 |
1187 | C<many_to_many> allows us to use the shorter |
1188 | C<$book-E<gt>author-E<gt>first-E<gt>last_name>. Note that you cannot |
1189 | define a C<many_to_many> relationship without also having the |
1190 | C<has_many> relationship in place. |
3533daff |
1191 | |
3b1fa91b |
1192 | Then edit C<lib/MyApp/Schema/Result/Author.pm> and add relationship |
3533daff |
1193 | information as follows (again, be careful to put in above the C<1;> but |
1194 | below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> comment): |
1195 | |
3533daff |
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(). |
fce83e5f |
1202 | __PACKAGE__->many_to_many(books => 'book_authors', 'book'); |
3533daff |
1203 | |
1390ef0e |
1204 | =head2 Run The Application |
3533daff |
1205 | |
4d63a0d5 |
1206 | Run the Catalyst development server script with the C<DBIC_TRACE> option |
1207 | (it might still be enabled from earlier in the tutorial, but here is an |
1208 | alternate way to specify the option just in case): |
3533daff |
1209 | |
1210 | $ DBIC_TRACE=1 script/myapp_server.pl |
1211 | |
1390ef0e |
1212 | Make sure that the application loads correctly and that you see the |
1213 | three dynamically created model class (one for each of the |
4ab6212d |
1214 | Result Classes we created). |
3533daff |
1215 | |
acbd7bdd |
1216 | Then hit the URL L<http://localhost:3000/books/list> with your browser |
444d6b27 |
1217 | and be sure that the book list still displays correctly. You can leave |
1218 | the development server running for the next step if you wish. |
3533daff |
1219 | |
c2dfb562 |
1220 | B<Note:> You will not see the authors yet because the view does not yet |
1221 | use the new relations. Read on to the next section where we update the |
1222 | template to do that. |
3533daff |
1223 | |
1224 | |
1225 | =head1 UPDATING THE VIEW |
1226 | |
acbd7bdd |
1227 | Let's add a new column to our book list page that takes advantage of |
1228 | the relationship information we manually added to our schema files in |
a46b474e |
1229 | the previous section. Edit C<root/src/books/list.tt2> and replace |
3b1fa91b |
1230 | the "empty" table cell "<td></td>" with the following: |
3533daff |
1231 | |
acbd7bdd |
1232 | ... |
3533daff |
1233 | <td> |
fce83e5f |
1234 | [% # NOTE: See Chapter 4 for a better way to do this! -%] |
3533daff |
1235 | [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%] |
1236 | [% # loop in 'side effect notation' to load just the last names of the -%] |
6d97b973 |
1237 | [% # authors into the list. Note that the 'push' TT vmethod doesn't return -%] |
3533daff |
1238 | [% # a value, so nothing will be printed here. But, if you have something -%] |
6d97b973 |
1239 | [% # in TT that does return a value and you don't want it printed, you -%] |
1240 | [% # 1) assign it to a bogus value, or -%] |
1241 | [% # 2) use the CALL keyword to call it and discard the return value. -%] |
3533daff |
1242 | [% tt_authors = [ ]; |
1243 | tt_authors.push(author.last_name) FOREACH author = book.authors %] |
1244 | [% # Now use a TT 'virtual method' to display the author count in parens -%] |
1245 | [% # Note the use of the TT filter "| html" to escape dangerous characters -%] |
1246 | ([% tt_authors.size | html %]) |
1247 | [% # Use another TT vmethod to join & print the names & comma separators -%] |
1248 | [% tt_authors.join(', ') | html %] |
1249 | </td> |
acbd7bdd |
1250 | ... |
3533daff |
1251 | |
444d6b27 |
1252 | B<IMPORTANT NOTE:> Again, you should keep as much "logic code" as |
1253 | possible out of your views. This kind of logic belongs in your model |
fce83e5f |
1254 | (the same goes for controllers -- keep them as "thin" as possible and |
1255 | push all of the "complicated code" out to your model objects). Avoid |
1256 | code like you see in the previous example -- we are only using it here |
1257 | to show some extra features in TT until we get to the more advanced |
444d6b27 |
1258 | model features we will see in Chapter 4 (see |
fce83e5f |
1259 | L<Catalyst::Manual::Tutorial::04_BasicCRUD/EXPLORING THE POWER OF DBIC>). |
1260 | |
1390ef0e |
1261 | Then hit "Reload" in your browser (note that you don't need to reload |
3533daff |
1262 | the development server or use the C<-r> option when updating TT |
1390ef0e |
1263 | templates) and you should now see the number of authors each book has |
1264 | along with a comma-separated list of the authors' last names. (If you |
1265 | didn't leave the development server running from the previous step, |
1266 | you will obviously need to start it before you can refresh your |
1267 | browser window.) |
1268 | |
1269 | If you are still running the development server with C<DBIC_TRACE> |
1270 | enabled, you should also now see five more C<SELECT> statements in the |
1271 | debug output (one for each book as the authors are being retrieved by |
a46b474e |
1272 | DBIx::Class): |
3533daff |
1273 | |
fce83e5f |
1274 | SELECT me.id, me.title, me.rating FROM book me: |
3b1fa91b |
1275 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1276 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '1' |
3b1fa91b |
1277 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1278 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '2' |
3b1fa91b |
1279 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1280 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '3' |
3b1fa91b |
1281 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1282 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '4' |
3b1fa91b |
1283 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1284 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '5' |
c2dfb562 |
1285 | |
1286 | Also note in C<root/src/books/list.tt2> that we are using "| html", a |
1287 | type of TT filter, to escape characters such as E<lt> and E<gt> to < |
1288 | and > and avoid various types of dangerous hacks against your |
1289 | application. In a real application, you would probably want to put |
1290 | "| html" at the end of every field where a user has control over the |
1291 | information that can appear in that field (and can therefore inject |
1292 | markup or code if you don't "neutralize" those fields). In addition to |
1293 | "| html", Template Toolkit has a variety of other useful filters that |
1294 | can found in the documentation for |
1295 | L<Template::Filters|Template::Filters>. |
3533daff |
1296 | |
1297 | |
1390ef0e |
1298 | =head1 RUNNING THE APPLICATION FROM THE COMMAND LINE |
1299 | |
1300 | In some situations, it can be useful to run your application and |
1301 | display a page without using a browser. Catalyst lets you do this |
1302 | using the C<scripts/myapp_test.pl> script. Just supply the URL you |
1303 | wish to display and it will run that request through the normal |
1304 | controller dispatch logic and use the appropriate view to render the |
1305 | output (obviously, complex pages may dump a lot of text to your |
1306 | terminal window). For example, if you type: |
1307 | |
1308 | $ script/myapp_test.pl "/books/list" |
1309 | |
1310 | You should get the same text as if you visited |
1311 | L<http://localhost:3000/books/list> with the normal development server |
1312 | and asked your browser to view the page source. |
3533daff |
1313 | |
1390ef0e |
1314 | |
1315 | =head1 OPTIONAL INFORMATION |
1316 | |
4b4d3884 |
1317 | B<NOTE: The rest of this chapter of the tutorial is optional. You can |
3ab6187c |
1318 | skip to Chapter 4, L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD>, |
3533daff |
1319 | if you wish.> |
1320 | |
acbd7bdd |
1321 | |
8a472b34 |
1322 | =head2 Using 'RenderView' for the Default View |
1390ef0e |
1323 | |
1324 | Once your controller logic has processed the request from a user, it |
1325 | forwards processing to your view in order to generate the appropriate |
3533daff |
1326 | response output. Catalyst uses |
1390ef0e |
1327 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by |
4d63a0d5 |
1328 | default to automatically perform this operation. If you look in |
1390ef0e |
1329 | C<lib/MyApp/Controller/Root.pm>, you should see the empty |
3533daff |
1330 | definition for the C<sub end> method: |
1331 | |
1332 | sub end : ActionClass('RenderView') {} |
1333 | |
1390ef0e |
1334 | The following bullet points provide a quick overview of the |
3533daff |
1335 | C<RenderView> process: |
1336 | |
1337 | =over 4 |
1338 | |
1339 | =item * |
1340 | |
1341 | C<Root.pm> is designed to hold application-wide logic. |
1342 | |
1343 | =item * |
1344 | |
1390ef0e |
1345 | At the end of a given user request, Catalyst will call the most specific |
1346 | C<end> method that's appropriate. For example, if the controller for a |
1347 | request has an C<end> method defined, it will be called. However, if |
1348 | the controller does not define a controller-specific C<end> method, the |
3533daff |
1349 | "global" C<end> method in C<Root.pm> will be called. |
1350 | |
1351 | =item * |
1352 | |
1353 | Because the definition includes an C<ActionClass> attribute, the |
1354 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic |
1355 | will be executed B<after> any code inside the definition of C<sub end> |
1356 | is run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions> |
1357 | for more information on C<ActionClass>. |
1358 | |
1359 | =item * |
1360 | |
1390ef0e |
1361 | Because C<sub end> is empty, this effectively just runs the default |
1362 | logic in C<RenderView>. However, you can easily extend the |
1363 | C<RenderView> logic by adding your own code inside the empty method body |
1364 | (C<{}>) created by the Catalyst Helpers when we first ran the |
1365 | C<catalyst.pl> to initialize our application. See |
1366 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more |
4d63a0d5 |
1367 | detailed information on how to extend C<RenderView> in C<sub end>. |
3533daff |
1368 | |
1369 | =back |
1370 | |
1371 | |
fce83e5f |
1372 | =head2 RenderView's "dump_info" Feature |
1373 | |
1374 | One of the nice features of C<RenderView> is that it automatically |
1375 | allows you to add C<dump_info=1> to the end of any URL for your |
1376 | application and it will force the display of the "exception dump" |
1377 | screen to the client browser. You can try this out by starting the |
1378 | development server as before and then point your browser to this URL: |
1379 | |
1380 | http://localhost:3000/books/list?dump_info=1 |
1381 | |
1382 | You should get a page with the following message at the top: |
1383 | |
1384 | Caught exception in MyApp::Controller::Root->end "Forced debug - |
1385 | Scrubbed output at /usr/share/perl5/Catalyst/Action/RenderView.pm line 46." |
1386 | |
1387 | Along with a summary of your application's state at the end of the |
1388 | processing for that request. The "Stash" section should show a |
1389 | summarized version of the DBIC book model objects. If desired, you |
1390 | can adjust the summarization logic (called "scrubbing" logic) -- see |
1391 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for |
1392 | details. |
1393 | |
1394 | Note that you shouldn't need to worry about "normal clients" using |
1395 | this technique to "reverse engineer" your application -- C<RenderView> |
1396 | only supports the C<dump_info=1> feature when your application is |
1397 | running in C<-Debug> mode (something you won't do once you have your |
1398 | application deployed in production). |
1399 | |
1400 | |
3533daff |
1401 | =head2 Using The Default Template Name |
1402 | |
1390ef0e |
1403 | By default, C<Catalyst::View::TT> will look for a template that uses the |
1404 | same name as your controller action, allowing you to save the step of |
1405 | manually specifying the template name in each action. For example, this |
1406 | would allow us to remove the |
1407 | C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our |
1408 | C<list> action in the Books controller. Open |
3533daff |
1409 | C<lib/MyApp/Controller/Books.pm> in your editor and comment out this line |
1410 | to match the following (only the C<$c-E<gt>stash-E<gt>{template}> line |
1411 | has changed): |
1412 | |
1413 | =head2 list |
1414 | |
1415 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
1416 | |
1417 | =cut |
1418 | |
1419 | sub list : Local { |
1420 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
1421 | # 'Context' that's used to 'glue together' the various components |
1422 | # that make up the application |
1423 | my ($self, $c) = @_; |
1424 | |
1425 | # Retrieve all of the book records as book model objects and store in the |
1426 | # stash where they can be accessed by the TT template |
3b1fa91b |
1427 | $c->stash->{books} = [$c->model('DB::Book')->all]; |
3533daff |
1428 | |
1429 | # Set the TT template to use. You will almost always want to do this |
1430 | # in your action methods (actions methods respond to user input in |
1431 | # your controllers). |
1432 | #$c->stash->{template} = 'books/list.tt2'; |
1433 | } |
1434 | |
3533daff |
1435 | |
1390ef0e |
1436 | You should now be able to restart the development server as per the |
3533daff |
1437 | previous section and access the L<http://localhost:3000/books/list> |
1438 | as before. |
1439 | |
1440 | B<NOTE:> Please note that if you use the default template technique, |
1441 | you will B<not> be able to use either the C<$c-E<gt>forward> or |
4b4d3884 |
1442 | the C<$c-E<gt>detach> mechanisms (these are discussed in Chapter 2 and |
1443 | Chapter 9 of the Tutorial). |
3533daff |
1444 | |
3b1fa91b |
1445 | B<IMPORTANT:> Make sure that you do NOT skip the following section |
1446 | before continuing to the next chapter 4 Basic CRUD. |
3533daff |
1447 | |
fce83e5f |
1448 | |
4d63a0d5 |
1449 | =head2 Return To A Manually Specified Template |
3533daff |
1450 | |
1451 | In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach> |
1452 | later in the tutorial, you should remove the comment from the |
1453 | statement in C<sub list> in C<lib/MyApp/Controller/Books.pm>: |
1454 | |
1455 | $c->stash->{template} = 'books/list.tt2'; |
1456 | |
1390ef0e |
1457 | Then delete the C<TEMPLATE_EXTENSION> line in |
3533daff |
1458 | C<lib/MyApp/View/TT.pm>. |
1459 | |
1390ef0e |
1460 | You should then be able to restart the development server and |
3533daff |
1461 | access L<http://localhost:3000/books/list> in the same manner as |
1462 | with earlier sections. |
1463 | |
1464 | |
1465 | =head1 AUTHOR |
1466 | |
1467 | Kennedy Clark, C<hkclark@gmail.com> |
1468 | |
1469 | Please report any errors, issues or suggestions to the author. The |
1470 | most recent version of the Catalyst Tutorial can be found at |
59884771 |
1471 | L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>. |
3533daff |
1472 | |
45c7830f |
1473 | Copyright 2006-2008, Kennedy Clark, under Creative Commons License |
8482d557 |
1474 | (L<http://creativecommons.org/licenses/by-sa/3.0/us/>). |