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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 | |
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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<$c>) that Catalyst passes to every |
111 | component throughout the framework. |
112 | |
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113 | |
114 | By default, Catalyst enables three plugins/flags: |
115 | |
116 | =over 4 |
117 | |
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118 | =item * |
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119 | |
120 | C<-Debug> Flag |
121 | |
122 | Enables the Catalyst debug output you saw when we started the |
123 | C<script/myapp_server.pl> development server earlier. You can remove |
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124 | this item when you place your application into production. |
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125 | |
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126 | To be technically correct, it turns out that C<-Debug> is not a plugin, but a I<flag>. |
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127 | Although most of the items specified on the C<__PACKAGE__-E<gt>setup> |
128 | line of your application class will be plugins, Catalyst supports a |
129 | limited number of flag options (of these, C<-Debug> is the most |
130 | common). See the documentation for C<Catalyst.pm> to get details on |
131 | other flags (currently C<-Engine>, C<-Home>, and C<-Log>). |
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132 | |
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133 | If you prefer, there are several other ways to enable debug output: |
134 | |
135 | =over 4 |
136 | |
137 | =item * |
138 | |
139 | Use the C<$c-E<gt>debug> method |
140 | |
141 | =item * |
142 | |
143 | The C<-d> option to C<script/myapp_server.pl> |
144 | |
145 | =item * |
146 | |
147 | The C<CATALYST_DEBUG=1> environment variable (or set it to |
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148 | zero to temporarily disable debug output). |
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149 | |
150 | =back |
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151 | |
152 | B<TIP>: Depending on your needs, it can be helpful to permanently |
153 | remove C<-Debug> from C<lib/MyApp.pm> and then use the C<-d> option |
154 | to C<script/myapp_server.pl> to re-enable it just for the development |
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155 | server. We will not be using that approach in the tutorial, but feel |
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156 | free to make use of it in your own projects. |
157 | |
158 | =item * |
159 | |
160 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> |
161 | |
162 | C<ConfigLoader> provides an automatic way to load configurable |
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163 | parameters for your application from a central |
164 | L<Config::General|Config::General> file (versus having the values |
165 | hard-coded inside your Perl modules). Config::General uses syntax |
166 | very similar to Apache configuration files. We will see how to use |
167 | this feature of Catalyst during the authentication and authorization |
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168 | sections (Chapter 5 and Chapter 6). |
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169 | |
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170 | B<IMPORTANT NOTE:> If you are using a version of |
171 | L<Catalyst::Devel|Catalyst::Devel> prior to version 1.06, be aware |
172 | that Catalyst changed the default format from YAML to the more |
173 | straightforward C<Config::General> style. This tutorial uses the |
174 | newer C<myapp.conf> file for C<Config::General>. However, Catalyst |
175 | supports both formats and will automatically use either C<myapp.conf> |
176 | or C<myapp.yml> (or any other format supported by |
177 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> and |
178 | L<Config::Any|Config::Any>). If you are using a version of |
179 | Catalyst::Devel prior to 1.06, you can convert to the newer format by |
180 | simply creating the C<myapp.conf> file manually and deleting |
181 | C<myapp.yml>. The default contents of the C<myapp.conf> you create |
182 | should only consist of one line: |
183 | |
184 | name MyApp |
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185 | |
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186 | B<TIP>: This script can be useful for converting between configuration |
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187 | formats: |
188 | |
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189 | perl -Ilib -e 'use MyApp; use Config::General; |
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190 | Config::General->new->save_file("myapp.conf", MyApp->config);' |
191 | |
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192 | =item * |
193 | |
194 | L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple> |
195 | |
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196 | C<Static::Simple> provides an easy way to serve static content, such |
197 | as images and CSS files, from the development server. |
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198 | |
199 | =back |
200 | |
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201 | For our application, we want to add one new plugin into the mix. To |
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202 | do this, edit C<lib/MyApp.pm> (this file is generally referred to as |
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203 | your I<application class>) and delete the lines with: |
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204 | |
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205 | use Catalyst qw/ |
206 | -Debug |
207 | ConfigLoader |
208 | Static::Simple |
209 | /; |
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210 | |
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211 | Then replace it with: |
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212 | |
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213 | # Load plugins |
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214 | use Catalyst qw/ |
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215 | -Debug |
216 | ConfigLoader |
217 | Static::Simple |
218 | |
219 | StackTrace |
220 | /; |
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221 | |
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222 | B<Note:> Recent versions of C<Catalyst::Devel> have used a variety of |
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223 | techniques to load these plugins/flags. For example, you might see |
224 | the following: |
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225 | |
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226 | __PACKAGE__->setup(qw/-Debug ConfigLoader Static::Simple/); |
94d8da41 |
227 | |
228 | Don't let these variations confuse you -- they all accomplish the same |
229 | result. |
230 | |
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231 | This tells Catalyst to start using one additional plugin, |
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232 | L<Catalyst::Plugin::StackTrace>, to add a |
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233 | stack trace to the standard Catalyst "debug screen" (the screen |
234 | Catalyst sends to your browser when an error occurs). Be aware that |
235 | L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your |
236 | browser, not in the console window from which you're running your |
237 | application, which is where logging output usually goes. |
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238 | |
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239 | Make sure when adding new plugins you also include them as a new |
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240 | dependency within the Makefile.PL file. For example, after adding |
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241 | the StackTrace plugin the Makefile.PL should include the following |
242 | line: |
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 | |
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__> |
255 | is 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 |
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 |
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. |
321 | On the other hand, C<$c> will be new to many Perl programmers who have |
322 | not used Catalyst before (it's sometimes written as C<$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 |
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 |
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328 | attributes (the "C<:Local>" next to the "C<sub list>" in the code |
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329 | above) to provide additional information to the Catalyst dispatcher |
330 | logic (note that the space between the colon and the attribute name is |
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331 | optional; you will see attributes written both ways). Most Catalyst |
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332 | Controllers use 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 |
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339 | an action, but you do not want Catalyst to directly expose the method |
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340 | to your users. Catalyst will not map C<:Private> methods to a URI. |
341 | Use them for various sorts of "special" methods (the C<begin>, |
342 | C<auto>, etc. discussed below) or for methods you want to be able to |
343 | C<forward> or C<detach> to. (If the method is a plain old "helper |
344 | method" that you don't want to be an action at all, then just define |
345 | the method without any attribute -- you can call it in your code, but |
346 | the Catalyst 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 |
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374 | C<lib/MyApp/Controller/Books.pm> would match on the URL |
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375 | C<http://localhost:3000/books/list>, but "C<:Path('/list')>" would |
376 | match on C<http://localhost:3000/list> (because of the leading slash). |
377 | You can use C<:Args()> to specify how many arguments an action should |
378 | accept. See L<Catalyst::Manual::Intro/Action_types> for more |
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 |
384 | "C<:Path('_name_of_method_')>". For example, these are equivalent: |
385 | "C<sub create_book :Local {...}>" and |
386 | "C<sub create_book :Path('create_book') {...}>". |
387 | |
388 | =item * |
389 | |
390 | B<:Global> -- C<:Global> is merely a shorthand for |
391 | "C<:Path('/_name_of_method_')>". For example, these are equivalent: |
392 | "C<sub create_book :Global {...}>" and |
393 | "C<sub create_book :Path('/create_book') {...}>". |
394 | |
395 | =item * |
396 | |
397 | B<:Chained> -- Newer Catalyst applications tend to use the Chained |
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398 | dispatch form of action types because of its power and flexibility. |
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399 | It allows a series of controller methods to be automatically dispatched |
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400 | to service a single user request. See |
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401 | L<Catalyst::Manual::Tutorial::04_BasicCRUD|Catalyst::Manual::Tutorial::04_BasicCRUD> |
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402 | and L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained> |
403 | for more information on chained actions. |
404 | |
405 | =back |
406 | |
407 | You should refer to L<Catalyst::Manual::Intro/Action_types> for |
408 | additional information and for coverage of some lesser-used action |
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409 | types 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 |
431 | is L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT>. |
432 | You may also come across references to |
433 | L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite>, |
434 | but its use is now deprecated. |
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435 | |
436 | Enter the following command to enable the C<TT> style of view |
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437 | rendering for this tutorial: |
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" |
1edbdee6 |
442 | created "/home/me/MyApp/script/../lib/MyApp/View/HTML.pm" |
443 | created "/home/me/MyApp/script/../t/view_HTML.t" |
444 | |
445 | This simply creates a view called C<HTML> in a file called C<HTML.pm> (the first |
446 | argument). It is now up to you to decide how you want to structure your view |
447 | layout. For the tutorial, we will start with a very simple TT template to |
448 | initially demonstrate the concepts, but quickly migrate to a more typical |
449 | "wrapper page" type of configuration (where the "wrapper" controls the overall |
450 | "look and feel" of your site from a single file or set of files). |
451 | |
c062293d |
452 | Edit C<lib/MyApp/View/HTML.pm> and you should see |
453 | something similar to the following: |
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454 | |
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455 | __PACKAGE__->config( |
456 | TEMPLATE_EXTENSION => '.tt', |
457 | render_die => 1, |
458 | ); |
3533daff |
459 | |
1390ef0e |
460 | And update it to match: |
461 | |
462 | __PACKAGE__->config( |
463 | # Change default TT extension |
464 | TEMPLATE_EXTENSION => '.tt2', |
c062293d |
465 | render_die => 1, |
466 | ); |
467 | |
468 | This changes the default extension for Template Toolkit from '.tt' to |
469 | '.tt2'. |
470 | |
471 | You can also configure components in your application class. For example, |
472 | Edit C<lib/MyApp.pm> and you should see that the default: |
473 | |
474 | __PACKAGE__->setup; |
475 | |
476 | Above this, add config: |
477 | |
478 | __PACKAGE__->config( |
479 | 'View::HTML' => { |
480 | #Set the location for TT files |
481 | INCLUDE_PATH => [ |
482 | __PACKAGE__->path_to( 'root', 'src' ), |
1390ef0e |
483 | ], |
c062293d |
484 | }, |
1390ef0e |
485 | ); |
c062293d |
486 | # This line was here already |
487 | __PACKAGE__->setup; |
3533daff |
488 | |
c062293d |
489 | This changes the base directory for your template files from |
490 | C<root> to C<root/src>. |
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491 | |
c062293d |
492 | The reason to do this outside the C<lib/MyApp/View/HTML.pm> file |
493 | is that the template path is found with the C<path_to> method, |
494 | to get a path relative to the application root (no matter where it |
495 | is installed), but this requires the application to be loaded... |
496 | |
497 | Trying to set this setting in the view means that you have a chicken |
498 | and egg problem, in that the view requires the application to be loaded, |
499 | but loading the application loads the view. |
500 | |
501 | Putting the configuration which depends on the application class into |
502 | that class is the neatest way to avoid this issue. |
503 | |
504 | Please stick with the settings above for the duration of the |
505 | tutorial, but feel free to use whatever options you desire in your |
506 | applications (as with most things Perl, there's more than one way to |
444d6b27 |
507 | do it...). |
1390ef0e |
508 | |
acbd7bdd |
509 | B<Note:> We will use C<root/src> as the base directory for our |
444d6b27 |
510 | template files, with a full naming convention of |
acbd7bdd |
511 | C<root/src/_controller_name_/_action_name_.tt2>. Another popular option is to |
512 | use C<root/> as the base (with a full filename pattern of |
513 | C<root/_controller_name_/_action_name_.tt2>). |
514 | |
1390ef0e |
515 | =head2 Create a TT Template Page |
3533daff |
516 | |
517 | First create a directory for book-related TT templates: |
518 | |
1390ef0e |
519 | $ mkdir -p root/src/books |
3533daff |
520 | |
521 | Then create C<root/src/books/list.tt2> in your editor and enter: |
522 | |
523 | [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%] |
524 | [% # see this "chomping" in your browser because HTML ignores blank lines, but -%] |
525 | [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%] |
526 | [%- # optional, but both the beginning and the ending TT tags support chomping. -%] |
527 | |
1390ef0e |
528 | [% # Provide a title -%] |
3533daff |
529 | [% META title = 'Book List' -%] |
530 | |
531 | <table> |
532 | <tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr> |
533 | [% # Display each book in a table row %] |
534 | [% FOREACH book IN books -%] |
535 | <tr> |
536 | <td>[% book.title %]</td> |
537 | <td>[% book.rating %]</td> |
a46b474e |
538 | <td></td> |
3533daff |
539 | </tr> |
540 | [% END -%] |
541 | </table> |
542 | |
543 | As indicated by the inline comments above, the C<META title> line uses |
1390ef0e |
544 | TT's META feature to provide a title to the "wrapper" that we will |
545 | create later. Meanwhile, the C<FOREACH> loop iterates through each |
546 | C<book> model object and prints the C<title> and C<rating> fields. |
3533daff |
547 | |
4d63a0d5 |
548 | The C<[%> and C<%]> tags are used to delimit Template Toolkit code. TT |
549 | supports a wide variety of directives for "calling" other files, |
550 | looping, conditional logic, etc. In general, TT simplifies the usual |
444d6b27 |
551 | range of Perl operators down to the single dot (".") operator. This |
4d63a0d5 |
552 | applies to operations as diverse as method calls, hash lookups, and list |
553 | index values (see |
8c848468 |
554 | L<https://metacpan.org/module/Template::Manual::Variables> for |
444d6b27 |
555 | details and examples). In addition to the usual L<Template> module Pod |
4d63a0d5 |
556 | documentation, you can access the TT manual at |
8c848468 |
557 | L<https://metacpan.org/module/Template::Manual>. |
3533daff |
558 | |
444d6b27 |
559 | B<TIP:> While you can build all sorts of complex logic into your TT |
560 | templates, you should in general keep the "code" part of your |
561 | templates as simple as possible. If you need more complex logic, |
562 | create helper methods in your model that abstract out a set of code |
563 | into a single call from your TT template. (Note that the same is true |
564 | of your controller logic as well -- complex sections of code in your |
565 | controllers should often be pulled out and placed into your model |
566 | objects.) In Chapter 4 of the tutorial we will explore some extremely |
567 | helpful and powerful features of L<DBIx::Class> that allow you to pull |
568 | code out of your views and controllers and place it where it |
569 | rightfully belongs in a model class. |
1390ef0e |
570 | |
571 | |
572 | =head2 Test Run The Application |
573 | |
574 | To test your work so far, first start the development server: |
575 | |
f058768a |
576 | $ script/myapp_server.pl -r |
1390ef0e |
577 | |
578 | Then point your browser to L<http://localhost:3000> and you should |
579 | still get the Catalyst welcome page. Next, change the URL in your |
580 | browser to L<http://localhost:3000/books/list>. If you have |
581 | everything working so far, you should see a web page that displays |
582 | nothing other than our column headers for "Title", "Rating", and |
583 | "Author(s)" -- we will not see any books until we get the database and |
584 | model working below. |
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 |
429e7843 |
595 | create a database table and load some sample data. We will use |
9887a877 |
596 | SQLite (L<http://www.sqlite.org>), a popular database that is |
429e7843 |
597 | lightweight and easy to use. Be sure to get at least version 3. Open |
1390ef0e |
598 | C<myapp01.sql> in 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 | |
b66dd084 |
685 | Please note that here we have chosen to use 'singular' table names. This is |
e586b5f4 |
686 | because the default inflection code for older versions of |
b66dd084 |
687 | L<DBIx::Class::Schema::Loader> does NOT handle plurals. There has been much |
688 | philosophical discussion on whether table names should be plural or singular. |
689 | There is no one correct answer, as long as one makes a choice and remains |
658b8c29 |
690 | consistent with it. If you prefer plural table names (e.g. you think that they |
691 | are easier to read) then see the documentation in |
692 | L<DBIx::Class::Schema::Loader::Base/naming> (version 0.05 or greater). |
3b1fa91b |
693 | |
a6d800ac |
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 | |
27909ed4 |
700 | Catalyst can be used with virtually any form of datastore available |
701 | via Perl. For example, L<Catalyst::Model::DBI|Catalyst::Model::DBI> |
444d6b27 |
702 | can be used to access databases through the traditional Perl L<DBI> |
27909ed4 |
703 | interface or you can use a model to access files of any type on the |
704 | filesystem. However, most Catalyst applications use some form of |
705 | object-relational mapping (ORM) technology to create objects |
706 | associated with tables in a relational database. Matt Trout's |
707 | L<DBIx::Class|DBIx::Class> (abbreviated as "DBIC") has rapidly emerged |
708 | as the Perl-based ORM technology of choice. Most new Catalyst |
a46b474e |
709 | applications rely on DBIx::Class, as will this tutorial. |
3533daff |
710 | |
a46b474e |
711 | Although DBIx::Class has included support for a C<create=dynamic> mode |
712 | to automatically read the database structure every time the |
8fd01b0e |
713 | application starts, its use is no longer recommended. While it can |
a46b474e |
714 | make for "flashy" demos, the use of the C<create=static> mode we use |
715 | below can be implemented just as quickly and provides many advantages |
716 | (such as the ability to add your own methods to the overall DBIC |
717 | framework, a 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, |
3e008853 |
723 | L<Catalyst::Model::DBIC::Schema>, so |
f058768a |
724 | that we can take advantage of some recent enhancements in how |
725 | foreign keys are handled with SQLite. To check your version, |
726 | run this command: |
27909ed4 |
727 | |
728 | $ perl -MCatalyst::Model::DBIC::Schema -e \ |
729 | 'print "$Catalyst::Model::DBIC::Schema::VERSION\n"' |
f33d1dd7 |
730 | 0.4 |
27909ed4 |
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 | |
f33d1dd7 |
736 | If you are following along in Debian 5, you should have version 0.40 or |
737 | higher (shown above as "0.4" with the tailing zero removed). If you have |
738 | less than v0.39, you will need to run this command to install it |
739 | directly from CPAN: |
27909ed4 |
740 | |
3e008853 |
741 | $ cpan -i Catalyst::Model::DBIC::Schema |
27909ed4 |
742 | |
743 | And re-run the version print command to verify that you are now at |
f058768a |
744 | 0.39 or higher. |
745 | |
746 | In addition, since we are using SQLite's foreign key support here, |
747 | please be sure that you use version C<1.27> of L<DBD::SQLite> or later: |
748 | |
749 | $ perl -MDBD::SQLite -e 'print "$DBD::SQLite::VERSION\n"' |
750 | 1.29 |
751 | |
752 | Upgrade if you are not at version C<1.27> or higher. |
27909ed4 |
753 | |
3e008853 |
754 | Also, remember to put a line requiring the version of the module |
755 | you just installed into your Makefile.PL |
27909ed4 |
756 | |
a46b474e |
757 | =head2 Create Static DBIx::Class Schema Files |
27909ed4 |
758 | |
98fd8420 |
759 | Before you continue, make sure your C<myapp.db> database file is in |
760 | the application's topmost directory. Now use the model helper with |
761 | the C<create=static> option to read the database with |
27909ed4 |
762 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> and |
763 | automatically build the required files for us: |
3533daff |
764 | |
4ab6212d |
765 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \ |
b66dd084 |
766 | create=static dbi:SQLite:myapp.db \ |
767 | on_connect_do="PRAGMA foreign_keys = ON" |
1390ef0e |
768 | exists "/home/me/MyApp/script/../lib/MyApp/Model" |
769 | exists "/home/me/MyApp/script/../t" |
27909ed4 |
770 | Dumping manual schema for MyApp::Schema to directory /home/me/MyApp/script/../lib ... |
771 | Schema dump completed. |
1390ef0e |
772 | created "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm" |
773 | created "/home/me/MyApp/script/../t/model_DB.t" |
3533daff |
774 | |
fce83e5f |
775 | Please note the '\' above. Depending on your environment, you might |
776 | be able to cut and paste the text as shown or need to remove the '\' |
777 | character to that the command is all on a single line. |
3b1fa91b |
778 | |
27909ed4 |
779 | The C<script/myapp_create.pl> command breaks down like this: |
780 | |
781 | =over 4 |
782 | |
783 | =item * |
784 | |
785 | C<DB> is the name of the model class to be created by the helper in |
786 | C<lib/MyApp/Model>. |
787 | |
788 | =item * |
789 | |
790 | C<DBIC::Schema> is the type of the model to create. |
791 | |
792 | =item * |
793 | |
794 | C<MyApp::Schema> is the name of the DBIC schema file written to |
795 | C<lib/MyApp/Schema.pm>. |
796 | |
797 | =item * |
798 | |
799 | C<create=static> causes |
800 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to |
801 | load the schema as it runs and then write that information out |
802 | into files. |
803 | |
804 | =item * |
805 | |
f058768a |
806 | C<dbi:SQLite:myapp.db> is the standard DBI connect string |
27909ed4 |
807 | for use with SQLite. |
808 | |
f058768a |
809 | =item * |
810 | |
811 | And finally, the C<on_connect_do> string requests that |
812 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> create |
813 | foreign key relationships for us (this is not needed for databases such |
814 | as PostgreSQL and MySQL, but is required for SQLite). If you take a look |
815 | at C<lib/MyApp/Model/DB.pm>, you will see that the SQLite pragma is |
816 | propogated to the Model, so that SQLite's recent (and optional) foreign |
817 | key enforcement is enabled at the start of every database connection. |
818 | |
819 | |
820 | |
27909ed4 |
821 | =back |
822 | |
823 | If you look in the C<lib/MyApp/Schema.pm> file, you will find that it |
824 | only contains a call to the C<load_namespaces> method. You will also |
825 | find that C<lib/MyApp> contains a C<Schema> subdirectory, which then |
826 | has a subdirectory called "Result". This "Result" subdirectory then |
827 | has files named according to each of the tables in our simple database |
3b1fa91b |
828 | (C<Author.pm>, C<BookAuthor.pm>, and C<Book.pm>). These three |
a46b474e |
829 | files are called "Result Classes" in DBIx::Class nomenclature. Although the |
27909ed4 |
830 | Result Class files are named after tables in our database, the classes |
831 | correspond to the I<row-level data> that is returned by DBIC (more on |
832 | this later, especially in |
3ab6187c |
833 | L<Catalyst::Manual::Tutorial::04_BasicCRUD/EXPLORING THE POWER OF DBIC>). |
27909ed4 |
834 | |
835 | The idea with the Result Source files created under |
836 | C<lib/MyApp/Schema/Result> by the C<create=static> option is to only |
837 | edit the files below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> |
838 | warning. If you place all of your changes below that point in the |
839 | file, you can regenerate the automatically created information at the |
840 | top of each file should your database structure get updated. |
841 | |
842 | Also note the "flow" of the model information across the various files |
843 | and directories. Catalyst will initially load the model from |
844 | C<lib/MyApp/Model/DB.pm>. This file contains a reference to |
845 | C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, the |
846 | call to C<load_namespaces> in C<Schema.pm> will load each of the |
847 | "Result Class" files from the C<lib/MyApp/Schema/Result> subdirectory. |
848 | The final outcome is that Catalyst will dynamically create three |
849 | table-specific Catalyst models every time the application starts (you |
850 | can see these three model files listed in the debug output generated |
851 | when you launch the application). |
852 | |
853 | B<NOTE:> Older versions of |
854 | L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> use the |
a46b474e |
855 | deprecated DBIx::Class C<load_classes> technique instead of the newer |
46213071 |
856 | C<load_namespaces>. For new applications, please try to use |
27909ed4 |
857 | C<load_namespaces> since it more easily supports a very useful DBIC |
858 | technique called "ResultSet Classes." If you need to convert an |
859 | existing application from "load_classes" to "load_namespaces," you can |
b66dd084 |
860 | use this process to automate the migration, but first make sure you have |
861 | version C<0.39> of L<Catalyst::Model::DBIC::Schema> and |
862 | L<DBIx::Class::Schema::Loader> version C<0.05000> or later. |
27909ed4 |
863 | |
b66dd084 |
864 | $ # Re-run the helper to upgrade for you |
27909ed4 |
865 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \ |
b66dd084 |
866 | create=static naming=current use_namespaces=1 \ |
867 | dbi:SQLite:myapp.db \ |
868 | on_connect_do="PRAGMA foreign_keys = ON" |
dc9a0503 |
869 | |
f058768a |
870 | |
1390ef0e |
871 | =head1 ENABLE THE MODEL IN THE CONTROLLER |
872 | |
acbd7bdd |
873 | Open C<lib/MyApp/Controller/Books.pm> and un-comment the model code we |
874 | left disabled earlier so that your version matches the following (un- |
3b1fa91b |
875 | comment the line containing C<[$c-E<gt>model('DB::Book')-E<gt>all]> |
acbd7bdd |
876 | and delete the next 2 lines): |
1390ef0e |
877 | |
878 | =head2 list |
879 | |
880 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
881 | |
882 | =cut |
883 | |
f058768a |
884 | sub list :Local { |
1390ef0e |
885 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
886 | # 'Context' that's used to 'glue together' the various components |
887 | # that make up the application |
888 | my ($self, $c) = @_; |
889 | |
f058768a |
890 | # Retrieve all of the book records as book model objects and store |
891 | # in the stash where they can be accessed by the TT template |
0ed3df53 |
892 | $c->stash(books => [$c->model('DB::Book')->all]); |
1390ef0e |
893 | |
894 | # Set the TT template to use. You will almost always want to do this |
895 | # in your action methods (action methods respond to user input in |
896 | # your controllers). |
61cb69fd |
897 | $c->stash(template => 'books/list.tt2'); |
1390ef0e |
898 | } |
899 | |
3b1fa91b |
900 | B<TIP>: You may see the C<$c-E<gt>model('DB::Book')> un-commented |
901 | above written as C<$c-E<gt>model('DB')-E<gt>resultset('Book')>. The |
c93b5eaa |
902 | two are equivalent. Either way, C<$c-E<gt>model> returns a |
903 | L<DBIx::Class::ResultSet|DBIx::Class::ResultSet> which handles queries |
4d63a0d5 |
904 | against the database and iterating over the set of results that is |
c93b5eaa |
905 | returned. |
906 | |
907 | We are using the C<-E<gt>all> to fetch all of the books. DBIC |
908 | supports a wide variety of more advanced operations to easily do |
909 | things like filtering and sorting the results. For example, the |
518f3851 |
910 | following could be used to sort the results by descending title: |
c93b5eaa |
911 | |
3b1fa91b |
912 | $c->model('DB::Book')->search({}, {order_by => 'title DESC'}); |
c93b5eaa |
913 | |
914 | Some other examples are provided in |
915 | L<DBIx::Class::Manual::Cookbook/Complex WHERE clauses>, with |
916 | additional information found at L<DBIx::Class::ResultSet/search>, |
917 | L<DBIx::Class::Manual::FAQ/Searching>, |
918 | L<DBIx::Class::Manual::Intro|DBIx::Class::Manual::Intro> |
919 | and L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>. |
1390ef0e |
920 | |
921 | |
922 | =head2 Test Run The Application |
3533daff |
923 | |
1435672d |
924 | First, let's enable an environment variable that causes DBIx::Class to |
acbd7bdd |
925 | dump the SQL statements used to access the database. This is a |
1435672d |
926 | helpful trick when you are trying to debug your database-oriented |
f058768a |
927 | code. Press C<Ctrl-C> to break out of the development server and |
928 | enter: |
3533daff |
929 | |
930 | $ export DBIC_TRACE=1 |
f058768a |
931 | $ script/myapp_server.pl -r |
f33d1dd7 |
932 | |
4d63a0d5 |
933 | This assumes you are using bash as your shell -- adjust accordingly if |
3533daff |
934 | you are using a different shell (for example, under tcsh, use |
935 | C<setenv DBIC_TRACE 1>). |
936 | |
d0496197 |
937 | B<NOTE:> You can also set this in your code using |
3533daff |
938 | C<$class-E<gt>storage-E<gt>debug(1);>. See |
939 | L<DBIx::Class::Manual::Troubleshooting> for details (including options |
4d63a0d5 |
940 | to log to a file instead of displaying to the Catalyst development server |
3533daff |
941 | log). |
942 | |
1390ef0e |
943 | Then launch the Catalyst development server. The log output should |
944 | display something like: |
3533daff |
945 | |
f058768a |
946 | $ script/myapp_server.pl -r |
3533daff |
947 | [debug] Debug messages enabled |
1390ef0e |
948 | [debug] Statistics enabled |
3533daff |
949 | [debug] Loaded plugins: |
950 | .----------------------------------------------------------------------------. |
a467a714 |
951 | | Catalyst::Plugin::ConfigLoader 0.27 | |
952 | | Catalyst::Plugin::StackTrace 0.11 | |
3533daff |
953 | '----------------------------------------------------------------------------' |
954 | |
955 | [debug] Loaded dispatcher "Catalyst::Dispatcher" |
956 | [debug] Loaded engine "Catalyst::Engine::HTTP" |
957 | [debug] Found home "/home/me/MyApp" |
45d511e0 |
958 | [debug] Loaded Config "/home/me/MyApp/myapp.conf" |
3533daff |
959 | [debug] Loaded components: |
960 | .-----------------------------------------------------------------+----------. |
961 | | Class | Type | |
962 | +-----------------------------------------------------------------+----------+ |
963 | | MyApp::Controller::Books | instance | |
964 | | MyApp::Controller::Root | instance | |
d0496197 |
965 | | MyApp::Model::DB | instance | |
3b1fa91b |
966 | | MyApp::Model::DB::Author | class | |
967 | | MyApp::Model::DB::Book | class | |
968 | | MyApp::Model::DB::BookAuthor | class | |
1edbdee6 |
969 | | MyApp::View::HTML | instance | |
3533daff |
970 | '-----------------------------------------------------------------+----------' |
971 | |
972 | [debug] Loaded Private actions: |
973 | .----------------------+--------------------------------------+--------------. |
974 | | Private | Class | Method | |
975 | +----------------------+--------------------------------------+--------------+ |
976 | | /default | MyApp::Controller::Root | default | |
977 | | /end | MyApp::Controller::Root | end | |
1390ef0e |
978 | | /index | MyApp::Controller::Root | index | |
3533daff |
979 | | /books/index | MyApp::Controller::Books | index | |
980 | | /books/list | MyApp::Controller::Books | list | |
981 | '----------------------+--------------------------------------+--------------' |
982 | |
983 | [debug] Loaded Path actions: |
984 | .-------------------------------------+--------------------------------------. |
985 | | Path | Private | |
986 | +-------------------------------------+--------------------------------------+ |
1390ef0e |
987 | | / | /default | |
988 | | / | /index | |
989 | | /books | /books/index | |
3533daff |
990 | | /books/list | /books/list | |
991 | '-------------------------------------+--------------------------------------' |
992 | |
f058768a |
993 | [info] MyApp powered by Catalyst 5.80020 |
acbd7bdd |
994 | You can connect to your server at http://debian:3000 |
3533daff |
995 | |
1390ef0e |
996 | B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from |
997 | the 'base' directory of your application, not inside the C<script> |
998 | directory itself or it will not be able to locate the C<myapp.db> |
999 | database file. You can use a fully qualified or a relative path to |
1000 | locate the database file, but we did not specify that when we ran the |
3533daff |
1001 | model helper earlier. |
1002 | |
1003 | Some things you should note in the output above: |
1004 | |
1005 | =over 4 |
1006 | |
1390ef0e |
1007 | =item * |
3533daff |
1008 | |
1390ef0e |
1009 | Catalyst::Model::DBIC::Schema dynamically created three model classes, |
1010 | one to represent each of the three tables in our database |
3b1fa91b |
1011 | (C<MyApp::Model::DB::Author>, C<MyApp::Model::DB::BookAuthor>, |
1012 | and C<MyApp::Model::DB::Book>). |
3533daff |
1013 | |
1390ef0e |
1014 | =item * |
3533daff |
1015 | |
1016 | The "list" action in our Books controller showed up with a path of |
1017 | C</books/list>. |
1018 | |
1019 | =back |
1020 | |
1021 | Point your browser to L<http://localhost:3000> and you should still get |
1022 | the Catalyst welcome page. |
1023 | |
1024 | Next, to view the book list, change the URL in your browser to |
1025 | L<http://localhost:3000/books/list>. You should get a list of the five |
1390ef0e |
1026 | books loaded by the C<myapp01.sql> script above without any formatting. |
1027 | The rating for each book should appear on each row, but the "Author(s)" |
191dee29 |
1028 | column will still be blank (we will fill that in later). |
3533daff |
1029 | |
a46b474e |
1030 | Also notice in the output of the C<script/myapp_server.pl> that |
1031 | DBIx::Class used the following SQL to retrieve the data: |
3533daff |
1032 | |
fce83e5f |
1033 | SELECT me.id, me.title, me.rating FROM book me |
3533daff |
1034 | |
1035 | because we enabled DBIC_TRACE. |
1036 | |
0c51850e |
1037 | You now have the beginnings of a simple but workable web application. |
3533daff |
1038 | Continue on to future sections and we will develop the application |
1039 | more fully. |
1040 | |
1041 | |
1390ef0e |
1042 | =head1 CREATE A WRAPPER FOR THE VIEW |
1043 | |
acbd7bdd |
1044 | When using TT, you can (and should) create a wrapper that will |
1390ef0e |
1045 | literally wrap content around each of your templates. This is |
1046 | certainly useful as you have one main source for changing things that |
1047 | will appear across your entire site/application instead of having to |
1048 | edit many individual files. |
1049 | |
1050 | |
1edbdee6 |
1051 | =head2 Configure HTML.pm For The Wrapper |
1390ef0e |
1052 | |
1053 | In order to create a wrapper, you must first edit your TT view and |
444d6b27 |
1054 | tell it where to find your wrapper file. |
1390ef0e |
1055 | |
fb433ec4 |
1056 | Edit your TT view in C<lib/MyApp/View/HTML.pm> and change it to match the |
444d6b27 |
1057 | following: |
1390ef0e |
1058 | |
1059 | __PACKAGE__->config( |
1060 | # Change default TT extension |
1061 | TEMPLATE_EXTENSION => '.tt2', |
1062 | # Set the location for TT files |
1063 | INCLUDE_PATH => [ |
c2dfb562 |
1064 | MyApp->path_to( 'root', 'src' ), |
1390ef0e |
1065 | ], |
1066 | # Set to 1 for detailed timer stats in your HTML as comments |
1067 | TIMER => 0, |
1068 | # This is your wrapper template located in the 'root/src' |
1069 | WRAPPER => 'wrapper.tt2', |
1070 | ); |
1071 | |
1072 | |
1073 | =head2 Create the Wrapper Template File and Stylesheet |
1074 | |
1075 | Next you need to set up your wrapper template. Basically, you'll want |
1076 | to take the overall layout of your site and put it into this file. |
1077 | For the tutorial, open C<root/src/wrapper.tt2> and input the following: |
1078 | |
1079 | <?xml version="1.0" encoding="UTF-8"?> |
1080 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> |
1081 | <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> |
1082 | <head> |
1083 | <title>[% template.title or "My Catalyst App!" %]</title> |
1084 | <link rel="stylesheet" href="[% c.uri_for('/static/css/main.css') %]" /> |
1085 | </head> |
1086 | |
1087 | <body> |
1088 | <div id="outer"> |
1089 | <div id="header"> |
1090 | [%# Your logo could go here -%] |
1091 | <img src="[% c.uri_for('/static/images/btn_88x31_powered.png') %]" /> |
1092 | [%# Insert the page title -%] |
1093 | <h1>[% template.title or site.title %]</h1> |
1094 | </div> |
1095 | |
1096 | <div id="bodyblock"> |
1097 | <div id="menu"> |
1098 | Navigation: |
1099 | <ul> |
1100 | <li><a href="[% c.uri_for('/books/list') %]">Home</a></li> |
1101 | <li><a href="[% c.uri_for('/') %]" title="Catalyst Welcome Page">Welcome</a></li> |
1390ef0e |
1102 | </ul> |
1103 | </div><!-- end menu --> |
1104 | |
1105 | <div id="content"> |
1106 | [%# Status and error messages %] |
1107 | <span class="message">[% status_msg %]</span> |
1108 | <span class="error">[% error_msg %]</span> |
1109 | [%# This is where TT will stick all of your template's contents. -%] |
1110 | [% content %] |
1111 | </div><!-- end content --> |
1112 | </div><!-- end bodyblock --> |
1113 | |
1114 | <div id="footer">Copyright (c) your name goes here</div> |
c2dfb562 |
1115 | </div><!-- end outer --> |
1390ef0e |
1116 | |
1117 | </body> |
1118 | </html> |
1119 | |
1120 | Notice the status and error message sections in the code above: |
1121 | |
1122 | <span class="status">[% status_msg %]</span> |
1123 | <span class="error">[% error_msg %]</span> |
1124 | |
1125 | If we set either message in the Catalyst stash (e.g., |
1126 | C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it |
1127 | will be displayed whenever any view used by that request is rendered. |
1128 | The C<message> and C<error> CSS styles can be customized to suit your |
1129 | needs in the C<root/static/css/main.css> file we create below. |
1130 | |
1131 | B<Notes:> |
1132 | |
1133 | =over 4 |
1134 | |
1135 | =item * |
1136 | |
1137 | The Catalyst stash only lasts for a single HTTP request. If |
1138 | you need to retain information across requests you can use |
1139 | L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use |
4b4d3884 |
1140 | Catalyst sessions in the Authentication chapter of the tutorial). |
1390ef0e |
1141 | |
1142 | =item * |
1143 | |
1144 | Although it is beyond the scope of this tutorial, you may wish to use |
1145 | a JavaScript or AJAX tool such as jQuery (L<http://www.jquery.com>) or |
1146 | Dojo (L<http://www.dojotoolkit.org>). |
1147 | |
1148 | =back |
1149 | |
1150 | |
1151 | =head3 Create A Basic Stylesheet |
1152 | |
1153 | First create a central location for stylesheets under the static |
1154 | directory: |
1155 | |
1156 | $ mkdir root/static/css |
1157 | |
1158 | Then open the file C<root/static/css/main.css> (the file referenced in |
1159 | the stylesheet href link of our wrapper above) and add the following |
1160 | content: |
1161 | |
1162 | #header { |
1163 | text-align: center; |
1164 | } |
1165 | #header h1 { |
1166 | margin: 0; |
1167 | } |
1168 | #header img { |
1169 | float: right; |
1170 | } |
1171 | #footer { |
1172 | text-align: center; |
1173 | font-style: italic; |
1174 | padding-top: 20px; |
1175 | } |
1176 | #menu { |
1177 | font-weight: bold; |
1178 | background-color: #ddd; |
1179 | } |
1180 | #menu ul { |
1181 | list-style: none; |
1182 | float: left; |
1183 | margin: 0; |
1184 | padding: 0 0 50% 5px; |
1185 | font-weight: normal; |
1186 | background-color: #ddd; |
1187 | width: 100px; |
1188 | } |
1189 | #content { |
1190 | margin-left: 120px; |
1191 | } |
1192 | .message { |
1193 | color: #390; |
1194 | } |
1195 | .error { |
1196 | color: #f00; |
1197 | } |
1198 | |
1199 | You may wish to check out a "CSS Framework" like Emastic |
1200 | (L<http://code.google.com/p/emastic/>) as a way to quickly |
1201 | provide lots of high-quality CSS functionality. |
1202 | |
1203 | |
1204 | =head2 Test Run The Application |
1205 | |
f058768a |
1206 | Hit "Reload" in your web browser and you should now see a formatted |
1207 | version of our basic book list. (Again, the development server should |
1208 | have automatically restarted when you made changes to |
1edbdee6 |
1209 | C<lib/MyApp/View/HTML.pm>. If you are not using the "-r" option, you will |
f058768a |
1210 | need to hit C<Ctrl-C> and manually restart it. Also note that the |
1211 | development server does I<NOT> need to restart for changes to the TT and |
1212 | static files we created and edited in the C<root> directory -- those |
1213 | updates are handled on a per-request basis.) |
1214 | |
1215 | Although our wrapper and stylesheet are obviously very simple, you |
1216 | should see how it allows us to control the overall look of an entire |
1217 | website from two central files. To add new pages to the site, just |
1218 | provide a template that fills in the C<content> section of our wrapper |
1219 | template -- the wrapper will provide the overall feel of the page. |
1390ef0e |
1220 | |
1221 | |
a46b474e |
1222 | =head2 Updating the Generated DBIx::Class Result Class Files |
3533daff |
1223 | |
f058768a |
1224 | If you take a look at the Schema files automatically generated by |
1225 | L<DBIx::Class::Schema::Loader>, you will see that it has already defined |
1226 | C<has_many> and C<belongs_to> relationships on each side of our foreign |
1227 | keys. For example, take a look at C<lib/MyApp/Schema/Result/Book.pm> and |
1228 | notice the following code: |
1229 | |
1230 | =head1 RELATIONS |
1231 | |
1232 | =head2 book_authors |
1233 | |
1234 | Type: has_many |
1235 | |
1236 | Related object: L<MyApp::Schema::Result::BookAuthor> |
1237 | |
1238 | =cut |
1239 | |
1240 | __PACKAGE__->has_many( |
1241 | "book_authors", |
1242 | "MyApp::Schema::Result::BookAuthor", |
1243 | { "foreign.book_id" => "self.id" }, |
1244 | ); |
1245 | |
1246 | Each C<Book> "has_many" C<book_authors>, where C<BookAuthor> is |
1247 | the many-to-many table that allows each Book to have multiple |
1248 | Authors, and each Author to have mulitple books. The arguments |
1249 | to C<has_many> are: |
1250 | |
1251 | =over 4 |
1252 | |
1253 | =item * |
1254 | |
1255 | C<book_authors> - The name for this relationship. DBIC will create |
1256 | an accessor on the C<Books> DBIC Row object with this name. |
1257 | |
1258 | =item * |
1259 | |
1260 | C<MyApp::Schema::Result::BookAuthor> - The name of the DBIC model |
1261 | class referenced by this C<has_many> relationship. |
1262 | |
1263 | =item * |
1264 | |
1265 | C<foreign.book_id> - C<book_id> is the name of the foreign key |
1266 | column in the I<foreign> table that points back to this table. |
1267 | |
1268 | =item * |
1269 | |
1270 | C<self.id> - C<id> is the name of the column in I<this> table |
1271 | that is referenced by the foreign key. |
1272 | |
1273 | =back |
1274 | |
1275 | See L<DBIx::Class::Relationship/has_many> for |
1276 | additional information. Note that you might see a "hand coded" |
1277 | version of the C<has_many> relationship above expressed as: |
1278 | |
1279 | __PACKAGE__->has_many( |
1280 | "book_authors", |
1281 | "MyApp::Schema::Result::BookAuthor", |
1282 | "book_id", |
1283 | ); |
1284 | |
1285 | Where the third argument is simply the name of the column in |
1286 | the foreign table. However, the hashref syntax used by |
1287 | L<DBIx::Class::Schema::Loader> is more flexible (for example, |
1288 | it can handle "multi-column" foreign keys). |
1289 | |
1290 | B<Note:> If you are using older versions of SQLite and related DBIC |
1291 | tools, you will need to manually define your C<has_many> and |
1292 | C<belongs_to> relationships. We recommend upgrading to the versions |
1293 | specified above. :-) |
1294 | |
1295 | Have a look at C<lib/MyApp/Schema/Result/BookAuthor.pm> and notice |
1296 | that there is a C<belongs_to> relationship defined that acts as the |
1297 | "mirror image" to the C<has_many> relationship we just looked at |
1298 | above: |
1299 | |
1300 | =head1 RELATIONS |
1301 | |
1302 | =head2 book |
1303 | |
1304 | Type: belongs_to |
1305 | |
1306 | Related object: L<MyApp::Schema::Result::Book> |
1307 | |
1308 | =cut |
1309 | |
1310 | __PACKAGE__->belongs_to( |
1311 | "book", |
1312 | "MyApp::Schema::Result::Book", |
1313 | { id => "book_id" }, |
1314 | { join_type => "LEFT" }, |
1315 | ); |
1316 | |
f058768a |
1317 | The arguments are similar, but see |
1318 | L<DBIx::Class::Relationship/belongs_to> for the details. |
f33d1dd7 |
1319 | |
f058768a |
1320 | Although recent versions of SQLite and L<DBIx::Class::Schema::Loader> |
1321 | automatically handle the C<has_many> and C<belongs_to> relationships, |
7040a6cd |
1322 | C<many_to_many> relationship bridges (not technically a relationship) |
1323 | currently need to be manually inserted. |
1324 | To add a C<many_to_many> relationship bridge, first edit |
f058768a |
1325 | C<lib/MyApp/Schema/Result/Book.pm> and add the following text below |
1326 | the C<# You can replace this text...> comment: |
3533daff |
1327 | |
3533daff |
1328 | # many_to_many(): |
1329 | # args: |
7040a6cd |
1330 | # 1) Name of relationship bridge, DBIC will create accessor with this name |
1390ef0e |
1331 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
1332 | # 3) Name of belongs_to() relationship in model class of has_many() above |
3533daff |
1333 | # You must already have the has_many() defined to use a many_to_many(). |
fce83e5f |
1334 | __PACKAGE__->many_to_many(authors => 'book_authors', 'author'); |
3533daff |
1335 | |
3533daff |
1336 | B<Note:> Be careful to put this code I<above> the C<1;> at the end of the |
1337 | file. As with any Perl package, we need to end the last line with |
1338 | a statement that evaluates to C<true>. This is customarily done with |
1339 | C<1;> on a line by itself. |
1340 | |
7040a6cd |
1341 | The C<many_to_many> relationship bridge is optional, but it makes it |
b66dd084 |
1342 | easier to map a book to its collection of authors. Without |
93dcb966 |
1343 | it, we would have to "walk" through the C<book_author> table as in |
3b1fa91b |
1344 | C<$book-E<gt>book_author-E<gt>first-E<gt>author-E<gt>last_name> (we |
a46b474e |
1345 | will see examples on how to use DBIx::Class objects in your code soon, |
3b1fa91b |
1346 | but note that because C<$book-E<gt>book_author> can return multiple |
1390ef0e |
1347 | authors, we have to use C<first> to display a single author). |
5a82cb36 |
1348 | C<many_to_many> allows us to use the shorter |
1349 | C<$book-E<gt>author-E<gt>first-E<gt>last_name>. Note that you cannot |
7040a6cd |
1350 | define a C<many_to_many> relationship bridge without also having the |
5a82cb36 |
1351 | C<has_many> relationship in place. |
3533daff |
1352 | |
f058768a |
1353 | Then edit C<lib/MyApp/Schema/Result/Author.pm> and add the reverse |
7040a6cd |
1354 | C<many_to_many> relationship bridge for C<Author> as follows (again, be careful |
f058768a |
1355 | to put in above the C<1;> but below the C<# DO NOT MODIFY THIS OR |
1356 | ANYTHING ABOVE!> comment): |
3533daff |
1357 | |
3533daff |
1358 | # many_to_many(): |
1359 | # args: |
7040a6cd |
1360 | # 1) Name of relationship bridge, DBIC will create accessor with this name |
3533daff |
1361 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
1390ef0e |
1362 | # 3) Name of belongs_to() relationship in model class of has_many() above |
3533daff |
1363 | # You must already have the has_many() defined to use a many_to_many(). |
fce83e5f |
1364 | __PACKAGE__->many_to_many(books => 'book_authors', 'book'); |
3533daff |
1365 | |
f058768a |
1366 | |
1390ef0e |
1367 | =head2 Run The Application |
3533daff |
1368 | |
4d63a0d5 |
1369 | Run the Catalyst development server script with the C<DBIC_TRACE> option |
1370 | (it might still be enabled from earlier in the tutorial, but here is an |
f33d1dd7 |
1371 | alternate way to specify the trace option just in case): |
3533daff |
1372 | |
f058768a |
1373 | $ DBIC_TRACE=1 script/myapp_server.pl -r |
3533daff |
1374 | |
1390ef0e |
1375 | Make sure that the application loads correctly and that you see the |
1376 | three dynamically created model class (one for each of the |
4ab6212d |
1377 | Result Classes we created). |
3533daff |
1378 | |
acbd7bdd |
1379 | Then hit the URL L<http://localhost:3000/books/list> with your browser |
f33d1dd7 |
1380 | and be sure that the book list still displays correctly. |
3533daff |
1381 | |
c2dfb562 |
1382 | B<Note:> You will not see the authors yet because the view does not yet |
1383 | use the new relations. Read on to the next section where we update the |
1384 | template to do that. |
3533daff |
1385 | |
1386 | |
1387 | =head1 UPDATING THE VIEW |
1388 | |
acbd7bdd |
1389 | Let's add a new column to our book list page that takes advantage of |
1390 | the relationship information we manually added to our schema files in |
a46b474e |
1391 | the previous section. Edit C<root/src/books/list.tt2> and replace |
3b1fa91b |
1392 | the "empty" table cell "<td></td>" with the following: |
3533daff |
1393 | |
acbd7bdd |
1394 | ... |
3533daff |
1395 | <td> |
fce83e5f |
1396 | [% # NOTE: See Chapter 4 for a better way to do this! -%] |
3533daff |
1397 | [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%] |
1398 | [% # loop in 'side effect notation' to load just the last names of the -%] |
6d97b973 |
1399 | [% # authors into the list. Note that the 'push' TT vmethod doesn't return -%] |
3533daff |
1400 | [% # a value, so nothing will be printed here. But, if you have something -%] |
6d97b973 |
1401 | [% # in TT that does return a value and you don't want it printed, you -%] |
1402 | [% # 1) assign it to a bogus value, or -%] |
1403 | [% # 2) use the CALL keyword to call it and discard the return value. -%] |
3533daff |
1404 | [% tt_authors = [ ]; |
1405 | tt_authors.push(author.last_name) FOREACH author = book.authors %] |
1406 | [% # Now use a TT 'virtual method' to display the author count in parens -%] |
1407 | [% # Note the use of the TT filter "| html" to escape dangerous characters -%] |
1408 | ([% tt_authors.size | html %]) |
1409 | [% # Use another TT vmethod to join & print the names & comma separators -%] |
1410 | [% tt_authors.join(', ') | html %] |
1411 | </td> |
acbd7bdd |
1412 | ... |
3533daff |
1413 | |
444d6b27 |
1414 | B<IMPORTANT NOTE:> Again, you should keep as much "logic code" as |
1415 | possible out of your views. This kind of logic belongs in your model |
fce83e5f |
1416 | (the same goes for controllers -- keep them as "thin" as possible and |
1417 | push all of the "complicated code" out to your model objects). Avoid |
1418 | code like you see in the previous example -- we are only using it here |
1419 | to show some extra features in TT until we get to the more advanced |
444d6b27 |
1420 | model features we will see in Chapter 4 (see |
fce83e5f |
1421 | L<Catalyst::Manual::Tutorial::04_BasicCRUD/EXPLORING THE POWER OF DBIC>). |
1422 | |
1390ef0e |
1423 | Then hit "Reload" in your browser (note that you don't need to reload |
3533daff |
1424 | the development server or use the C<-r> option when updating TT |
1390ef0e |
1425 | templates) and you should now see the number of authors each book has |
1426 | along with a comma-separated list of the authors' last names. (If you |
1427 | didn't leave the development server running from the previous step, |
1428 | you will obviously need to start it before you can refresh your |
1429 | browser window.) |
1430 | |
1431 | If you are still running the development server with C<DBIC_TRACE> |
1432 | enabled, you should also now see five more C<SELECT> statements in the |
1433 | debug output (one for each book as the authors are being retrieved by |
a46b474e |
1434 | DBIx::Class): |
3533daff |
1435 | |
fce83e5f |
1436 | SELECT me.id, me.title, me.rating FROM book me: |
3b1fa91b |
1437 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1438 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '1' |
3b1fa91b |
1439 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1440 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '2' |
3b1fa91b |
1441 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1442 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '3' |
3b1fa91b |
1443 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1444 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '4' |
3b1fa91b |
1445 | SELECT author.id, author.first_name, author.last_name FROM book_author me |
fce83e5f |
1446 | JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '5' |
c2dfb562 |
1447 | |
1448 | Also note in C<root/src/books/list.tt2> that we are using "| html", a |
1449 | type of TT filter, to escape characters such as E<lt> and E<gt> to < |
1450 | and > and avoid various types of dangerous hacks against your |
1451 | application. In a real application, you would probably want to put |
1452 | "| html" at the end of every field where a user has control over the |
1453 | information that can appear in that field (and can therefore inject |
1454 | markup or code if you don't "neutralize" those fields). In addition to |
1455 | "| html", Template Toolkit has a variety of other useful filters that |
1456 | can found in the documentation for |
1457 | L<Template::Filters|Template::Filters>. |
3533daff |
1458 | |
1459 | |
1390ef0e |
1460 | =head1 RUNNING THE APPLICATION FROM THE COMMAND LINE |
1461 | |
1462 | In some situations, it can be useful to run your application and |
1463 | display a page without using a browser. Catalyst lets you do this |
1464 | using the C<scripts/myapp_test.pl> script. Just supply the URL you |
1465 | wish to display and it will run that request through the normal |
1466 | controller dispatch logic and use the appropriate view to render the |
1467 | output (obviously, complex pages may dump a lot of text to your |
1468 | terminal window). For example, if you type: |
1469 | |
1470 | $ script/myapp_test.pl "/books/list" |
1471 | |
1472 | You should get the same text as if you visited |
1473 | L<http://localhost:3000/books/list> with the normal development server |
1474 | and asked your browser to view the page source. |
3533daff |
1475 | |
1390ef0e |
1476 | |
1477 | =head1 OPTIONAL INFORMATION |
1478 | |
4b4d3884 |
1479 | B<NOTE: The rest of this chapter of the tutorial is optional. You can |
3ab6187c |
1480 | skip to Chapter 4, L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD>, |
3533daff |
1481 | if you wish.> |
1482 | |
acbd7bdd |
1483 | |
8a472b34 |
1484 | =head2 Using 'RenderView' for the Default View |
1390ef0e |
1485 | |
1486 | Once your controller logic has processed the request from a user, it |
1487 | forwards processing to your view in order to generate the appropriate |
3533daff |
1488 | response output. Catalyst uses |
1390ef0e |
1489 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by |
4d63a0d5 |
1490 | default to automatically perform this operation. If you look in |
1390ef0e |
1491 | C<lib/MyApp/Controller/Root.pm>, you should see the empty |
3533daff |
1492 | definition for the C<sub end> method: |
1493 | |
1494 | sub end : ActionClass('RenderView') {} |
1495 | |
1390ef0e |
1496 | The following bullet points provide a quick overview of the |
3533daff |
1497 | C<RenderView> process: |
1498 | |
1499 | =over 4 |
1500 | |
1501 | =item * |
1502 | |
1503 | C<Root.pm> is designed to hold application-wide logic. |
1504 | |
1505 | =item * |
1506 | |
1390ef0e |
1507 | At the end of a given user request, Catalyst will call the most specific |
1508 | C<end> method that's appropriate. For example, if the controller for a |
1509 | request has an C<end> method defined, it will be called. However, if |
1510 | the controller does not define a controller-specific C<end> method, the |
3533daff |
1511 | "global" C<end> method in C<Root.pm> will be called. |
1512 | |
1513 | =item * |
1514 | |
1515 | Because the definition includes an C<ActionClass> attribute, the |
1516 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic |
1517 | will be executed B<after> any code inside the definition of C<sub end> |
1518 | is run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions> |
1519 | for more information on C<ActionClass>. |
1520 | |
1521 | =item * |
1522 | |
1390ef0e |
1523 | Because C<sub end> is empty, this effectively just runs the default |
1524 | logic in C<RenderView>. However, you can easily extend the |
1525 | C<RenderView> logic by adding your own code inside the empty method body |
1526 | (C<{}>) created by the Catalyst Helpers when we first ran the |
1527 | C<catalyst.pl> to initialize our application. See |
1528 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more |
4d63a0d5 |
1529 | detailed information on how to extend C<RenderView> in C<sub end>. |
3533daff |
1530 | |
1531 | =back |
1532 | |
1533 | |
fce83e5f |
1534 | =head2 RenderView's "dump_info" Feature |
1535 | |
1536 | One of the nice features of C<RenderView> is that it automatically |
1537 | allows you to add C<dump_info=1> to the end of any URL for your |
1538 | application and it will force the display of the "exception dump" |
6961c906 |
1539 | screen to the client browser. You can try this out by pointing |
1540 | your browser to this URL: |
fce83e5f |
1541 | |
1542 | http://localhost:3000/books/list?dump_info=1 |
1543 | |
1544 | You should get a page with the following message at the top: |
1545 | |
1546 | Caught exception in MyApp::Controller::Root->end "Forced debug - |
1547 | Scrubbed output at /usr/share/perl5/Catalyst/Action/RenderView.pm line 46." |
1548 | |
1549 | Along with a summary of your application's state at the end of the |
1550 | processing for that request. The "Stash" section should show a |
1551 | summarized version of the DBIC book model objects. If desired, you |
1552 | can adjust the summarization logic (called "scrubbing" logic) -- see |
1553 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for |
1554 | details. |
1555 | |
1556 | Note that you shouldn't need to worry about "normal clients" using |
1557 | this technique to "reverse engineer" your application -- C<RenderView> |
1558 | only supports the C<dump_info=1> feature when your application is |
1559 | running in C<-Debug> mode (something you won't do once you have your |
1560 | application deployed in production). |
1561 | |
1562 | |
3533daff |
1563 | =head2 Using The Default Template Name |
1564 | |
1390ef0e |
1565 | By default, C<Catalyst::View::TT> will look for a template that uses the |
1566 | same name as your controller action, allowing you to save the step of |
1567 | manually specifying the template name in each action. For example, this |
1568 | would allow us to remove the |
1569 | C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our |
1570 | C<list> action in the Books controller. Open |
3533daff |
1571 | C<lib/MyApp/Controller/Books.pm> in your editor and comment out this line |
1572 | to match the following (only the C<$c-E<gt>stash-E<gt>{template}> line |
1573 | has changed): |
1574 | |
1575 | =head2 list |
1576 | |
1577 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
1578 | |
1579 | =cut |
1580 | |
ddfbd850 |
1581 | sub list :Local { |
3533daff |
1582 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
1583 | # 'Context' that's used to 'glue together' the various components |
1584 | # that make up the application |
1585 | my ($self, $c) = @_; |
1586 | |
1587 | # Retrieve all of the book records as book model objects and store in the |
1588 | # stash where they can be accessed by the TT template |
0ed3df53 |
1589 | $c->stash(books => [$c->model('DB::Book')->all]); |
3533daff |
1590 | |
1591 | # Set the TT template to use. You will almost always want to do this |
1592 | # in your action methods (actions methods respond to user input in |
1593 | # your controllers). |
61cb69fd |
1594 | #$c->stash(template => 'books/list.tt2'); |
3533daff |
1595 | } |
1596 | |
3533daff |
1597 | |
6961c906 |
1598 | You should now be able to access the L<http://localhost:3000/books/list> |
1599 | URL as before. |
3533daff |
1600 | |
1601 | B<NOTE:> Please note that if you use the default template technique, |
1602 | you will B<not> be able to use either the C<$c-E<gt>forward> or |
4b4d3884 |
1603 | the C<$c-E<gt>detach> mechanisms (these are discussed in Chapter 2 and |
1604 | Chapter 9 of the Tutorial). |
3533daff |
1605 | |
3b1fa91b |
1606 | B<IMPORTANT:> Make sure that you do NOT skip the following section |
1607 | before continuing to the next chapter 4 Basic CRUD. |
3533daff |
1608 | |
fce83e5f |
1609 | |
4d63a0d5 |
1610 | =head2 Return To A Manually Specified Template |
3533daff |
1611 | |
1612 | In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach> |
1613 | later in the tutorial, you should remove the comment from the |
1614 | statement in C<sub list> in C<lib/MyApp/Controller/Books.pm>: |
1615 | |
0ed3df53 |
1616 | $c->stash(template => 'books/list.tt2'); |
3533daff |
1617 | |
1390ef0e |
1618 | Then delete the C<TEMPLATE_EXTENSION> line in |
1edbdee6 |
1619 | C<lib/MyApp/View/HTML.pm>. |
3533daff |
1620 | |
6961c906 |
1621 | Check the L<http://localhost:3000/books/list> URL in your browser. |
1622 | It should look the same manner as with earlier sections. |
3533daff |
1623 | |
1624 | |
1625 | =head1 AUTHOR |
1626 | |
1627 | Kennedy Clark, C<hkclark@gmail.com> |
1628 | |
53243324 |
1629 | Feel free to contact the author for any errors or suggestions, but the |
1630 | best way to report issues is via the CPAN RT Bug system at |
1631 | <https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>. |
1632 | |
1633 | The most recent version of the Catalyst Tutorial can be found at |
59884771 |
1634 | L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>. |
3533daff |
1635 | |
ec3ef4ad |
1636 | Copyright 2006-2010, Kennedy Clark, under the |
1637 | Creative Commons Attribution Share-Alike License Version 3.0 |
8482d557 |
1638 | (L<http://creativecommons.org/licenses/by-sa/3.0/us/>). |