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1 | =head1 NAME |
2 | |
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3 | Catalyst::Manual::Tutorial::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 | |
16 | L<Introduction|Catalyst::Manual::Tutorial::Intro> |
17 | |
18 | =item 2 |
19 | |
20 | L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics> |
21 | |
22 | =item 3 |
23 | |
24 | B<More Catalyst Basics> |
25 | |
26 | =item 4 |
27 | |
28 | L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD> |
29 | |
30 | =item 5 |
31 | |
32 | L<Authentication|Catalyst::Manual::Tutorial::Authentication> |
33 | |
34 | =item 6 |
35 | |
36 | L<Authorization|Catalyst::Manual::Tutorial::Authorization> |
37 | |
38 | =item 7 |
39 | |
40 | L<Debugging|Catalyst::Manual::Tutorial::Debugging> |
41 | |
42 | =item 8 |
43 | |
44 | L<Testing|Catalyst::Manual::Tutorial::Testing> |
45 | |
46 | =item 9 |
47 | |
48 | L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD> |
49 | |
50 | =item 10 |
51 | |
52 | L<Appendices|Catalyst::Manual::Tutorial::Appendices> |
53 | |
54 | =back |
55 | |
56 | |
57 | =head1 DESCRIPTION |
58 | |
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59 | This 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::Intro|Catalyst::Manual::Tutorial::Intro>. |
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70 | |
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71 | Please take a look at |
72 | L<Catalyst::Manual::Tutorial::Intro/CATALYST INSTALLATION> before |
73 | doing the rest of this tutorial. Although the tutorial should work |
74 | correctly under most any recent version of Perl running on any |
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" |
94 | $ cd MyApp |
95 | |
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96 | This creates a similar skeletal structure to what we saw in Chapter 2 of |
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97 | the tutorial, except with C<MyApp> and C<myapp> substituted for |
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98 | C<Hello> and C<hello>. |
99 | |
100 | |
101 | =head1 EDIT THE LIST OF CATALYST PLUGINS |
102 | |
103 | One of the greatest benefits of Catalyst is that it has such a large |
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104 | library of plugins and base classes available. Plugins are used to |
105 | seamlessly integrate existing Perl modules into the overall Catalyst |
106 | framework. In general, they do this by adding additional methods to the |
107 | C<context> object (generally written as C<$c>) that Catalyst passes to |
108 | every component throughout the framework. |
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109 | |
110 | By default, Catalyst enables three plugins/flags: |
111 | |
112 | =over 4 |
113 | |
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114 | =item * |
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115 | |
116 | C<-Debug> Flag |
117 | |
118 | Enables the Catalyst debug output you saw when we started the |
119 | C<script/myapp_server.pl> development server earlier. You can remove |
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120 | this item when you place your application into production. |
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121 | |
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122 | As you may have noticed, C<-Debug> is not a plugin, but a I<flag>. |
123 | Although most of the items specified on the C<__PACKAGE__-E<gt>setup> |
124 | line of your application class will be plugins, Catalyst supports a |
125 | limited number of flag options (of these, C<-Debug> is the most |
126 | common). See the documentation for C<Catalyst.pm> to get details on |
127 | other flags (currently C<-Engine>, C<-Home>, and C<-Log>). |
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128 | |
129 | If you prefer, you can use the C<$c-E<gt>debug> method to enable debug |
130 | messages. |
131 | |
132 | B<TIP>: Depending on your needs, it can be helpful to permanently |
133 | remove C<-Debug> from C<lib/MyApp.pm> and then use the C<-d> option |
134 | to C<script/myapp_server.pl> to re-enable it just for the development |
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135 | server. We will not be using that approach in the tutorial, but feel |
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136 | free to make use of it in your own projects. |
137 | |
138 | =item * |
139 | |
140 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> |
141 | |
142 | C<ConfigLoader> provides an automatic way to load configurable |
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143 | parameters for your application from a central |
144 | L<Config::General|Config::General> file (versus having the values |
145 | hard-coded inside your Perl modules). Config::General uses syntax |
146 | very similar to Apache configuration files. We will see how to use |
147 | this feature of Catalyst during the authentication and authorization |
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148 | sections (Chapter 5 and Chapter 6). |
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149 | |
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150 | B<IMPORTANT NOTE:> If you are using a version of |
151 | L<Catalyst::Devel|Catalyst::Devel> prior to version 1.06, be aware |
152 | that Catalyst changed the default format from YAML to the more |
153 | straightforward C<Config::General> style. This tutorial uses the |
154 | newer C<myapp.conf> file for C<Config::General>. However, Catalyst |
155 | supports both formats and will automatically use either C<myapp.conf> |
156 | or C<myapp.yml> (or any other format supported by |
157 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> and |
158 | L<Config::Any|Config::Any>). If you are using a version of |
159 | Catalyst::Devel prior to 1.06, you can convert to the newer format by |
160 | simply creating the C<myapp.conf> file manually and deleting |
161 | C<myapp.yml>. The default contents of the C<myapp.conf> you create |
162 | should only consist of one line: |
163 | |
164 | name MyApp |
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165 | |
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166 | B<TIP>: This script can be useful for converting between configuration |
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167 | formats: |
168 | |
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169 | perl -Ilib -e 'use MyApp; use Config::General; |
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170 | Config::General->new->save_file("myapp.conf", MyApp->config);' |
171 | |
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172 | =item * |
173 | |
174 | L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple> |
175 | |
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176 | C<Static::Simple> provides an easy way to serve static content, such |
177 | as images and CSS files, from the development server. |
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178 | |
179 | =back |
180 | |
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181 | For our application, we want to add one new plugin into the mix. To |
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182 | do this, edit C<lib/MyApp.pm> (this file is generally referred to as |
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183 | your I<application class>) and delete the lines with: |
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184 | |
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185 | use Catalyst qw/-Debug |
186 | ConfigLoader |
187 | Static::Simple/; |
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188 | |
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189 | Then replace it with: |
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190 | |
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191 | # Load plugins |
192 | use Catalyst qw/-Debug |
193 | ConfigLoader |
194 | Static::Simple |
195 | |
196 | StackTrace |
197 | /; |
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198 | |
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199 | B<Note:> Recent versions of C<Catalyst::Devel> have used a variety of |
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200 | techniques to load these plugins/flags. For example, you might see |
201 | the following: |
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202 | |
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203 | __PACKAGE__->setup(qw/-Debug ConfigLoader Static::Simple/); |
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204 | |
205 | Don't let these variations confuse you -- they all accomplish the same |
206 | result. |
207 | |
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208 | This tells Catalyst to start using one new plugin, |
209 | L<Catalyst::Plugin::StackTrace|Catalyst::Plugin::StackTrace>, to add a |
210 | stack trace to the standard Catalyst "debug screen" (the screen |
211 | Catalyst sends to your browser when an error occurs). Be aware that |
212 | L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your |
213 | browser, not in the console window from which you're running your |
214 | application, which is where logging output usually goes. |
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215 | |
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216 | B<Notes:> |
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217 | |
218 | =over 4 |
219 | |
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220 | =item * |
221 | |
222 | C<__PACKAGE__> is just a shorthand way of referencing the name of the |
223 | package where it is used. Therefore, in C<MyApp.pm>, C<__PACKAGE__> |
224 | is equivalent to C<MyApp>. |
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225 | |
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226 | =item * |
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227 | |
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228 | You will want to disable L<StackTrace|Catalyst::Plugin::StackTrace> |
229 | before you put your application into production, but it can be helpful |
230 | during development. |
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231 | |
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232 | =item * |
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233 | |
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234 | When specifying plugins on the C<__PACKAGE__-E<gt>setup> line, you can |
235 | omit C<Catalyst::Plugin::> from the name. Additionally, you can |
236 | spread the plugin names across multiple lines as shown here, or place |
237 | them all on one (or more) lines as with the default configuration. |
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238 | |
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239 | =back |
240 | |
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241 | |
242 | =head1 CREATE A CATALYST CONTROLLER |
243 | |
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244 | As discussed earlier, controllers are where you write methods that |
245 | interact with user input. Typically, controller methods respond to |
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246 | C<GET> and C<POST> requests from the user's web browser. |
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247 | |
248 | Use the Catalyst C<create> script to add a controller for book-related |
249 | actions: |
250 | |
251 | $ script/myapp_create.pl controller Books |
252 | exists "/home/me/MyApp/script/../lib/MyApp/Controller" |
253 | exists "/home/me/MyApp/script/../t" |
254 | created "/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm" |
255 | created "/home/me/MyApp/script/../t/controller_Books.t" |
256 | |
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257 | Then edit C<lib/MyApp/Controller/Books.pm> (as discussed in Chapter 2 of |
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258 | the Tutorial, Catalyst has a separate directory under C<lib/MyApp> for |
259 | each of the three parts of MVC: C<Model>, C<View>, and C<Controller>) |
260 | and add the following method to the controller: |
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261 | |
262 | =head2 list |
263 | |
264 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
265 | |
266 | =cut |
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267 | |
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268 | sub list : Local { |
269 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
270 | # 'Context' that's used to 'glue together' the various components |
271 | # that make up the application |
272 | my ($self, $c) = @_; |
273 | |
274 | # Retrieve all of the book records as book model objects and store in the |
275 | # stash where they can be accessed by the TT template |
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276 | # $c->stash->{books} = [$c->model('DB::Books')->all]; |
277 | # But, for now, use this code until we create the model later |
278 | $c->stash->{books} = ''; |
279 | |
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280 | # Set the TT template to use. You will almost always want to do this |
281 | # in your action methods (action methods respond to user input in |
282 | # your controllers). |
283 | $c->stash->{template} = 'books/list.tt2'; |
284 | } |
285 | |
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286 | B<TIP>: See Appendix 1 for tips on removing the leading spaces when |
287 | cutting and pasting example code from POD-based documents. |
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288 | |
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289 | Programmers experienced with object-oriented Perl should recognize |
290 | C<$self> as a reference to the object where this method was called. |
291 | On the other hand, C<$c> will be new to many Perl programmers who have |
292 | not used Catalyst before (it's sometimes written as C<$context>). The |
293 | Context object is automatically passed to all Catalyst components. It |
294 | is used to pass information between components and provide access to |
295 | Catalyst and plugin functionality. |
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296 | |
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297 | Catalyst actions are regular Perl methods, but they make use of |
298 | attributes (the "C<: Local>" next to the "C<sub list>" in the code |
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299 | above) to provide additional information to the Catalyst dispatcher |
300 | logic (note that the space between the colon and the attribute name is |
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301 | optional; you will see attributes written both ways). Most Catalyst |
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302 | Controllers use one of five action types: |
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303 | |
304 | =over 4 |
305 | |
306 | =item * |
307 | |
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308 | B<:Private> -- Use C<:Private> for methods that you want to make into |
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309 | an action, but you do not want Catalyst to directly expose |
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310 | to your users. Catalyst will not map C<:Private> methods to a URI. |
311 | Use them for various sorts of "special" methods (the C<begin>, |
312 | C<auto>, etc. discussed below) or for methods you want to be able to |
313 | C<forward> or C<detach> to. (If the method is a plain old "helper |
314 | method" that you don't want to be an action at all, then just define |
315 | the method without any attribute -- you can call it in your code, but |
316 | the Catalyst dispatcher will ignore it.) |
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317 | |
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318 | There are five types of "special" build-in C<:Private> actions: |
319 | C<begin>, C<end>, C<default>, C<index>, and C<auto>. |
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320 | |
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321 | =over 4 |
322 | |
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323 | =item * |
324 | |
325 | With C<begin>, C<end>, C<default>, C<index> private actions, only the |
326 | most specific action of each type will be called. For example, if you |
327 | define a C<begin> action in your controller it will I<override> a |
328 | C<begin> action in your application/root controller -- I<only> the |
329 | action in your controller will be called. |
330 | |
331 | =item * |
332 | |
333 | Unlike the other actions where only a single method is called for each |
334 | request, I<every> auto action along the chain of namespaces will be |
335 | called. Each C<auto> action will be called I<from the application/root |
336 | controller down through the most specific class>. |
337 | |
338 | =back |
339 | |
340 | =item * |
341 | |
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342 | B<:Path> -- C<:Path> actions let you map a method to an explicit URI |
343 | path. For example, "C<:Path('list')>" in |
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344 | C<lib/MyApp/Controller/Books.pm> would match on the URL |
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345 | C<http://localhost:3000/books/list> but "C<:Path('/list')>" would match |
346 | on C<http://localhost:3000/list>. You can use C<:Args()> to specify |
347 | how many arguments an action should except. See |
348 | L<Catalyst::Manual::Intro/Action_types> for more information and a few |
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349 | examples. |
350 | |
351 | =item * |
352 | |
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353 | B<:Local> -- C<:Local> is merely a shorthand for |
354 | "C<:Path('_name_of_method_')>". For example, these are equivalent: |
355 | "C<sub create_book :Local {...}>" and |
356 | "C<sub create_book :Path('create_book') {...}>". |
357 | |
358 | =item * |
359 | |
360 | B<:Global> -- C<:Global> is merely a shorthand for |
361 | "C<:Path('/_name_of_method_')>". For example, these are equivalent: |
362 | "C<sub create_book :Global {...}>" and |
363 | "C<sub create_book :Path('/create_book') {...}>". |
364 | |
365 | =item * |
366 | |
367 | B<:Chained> -- Newer Catalyst applications tend to use the Chained |
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368 | dispatch form of action types because of its power and flexibility. |
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369 | It allows a series of controller methods to be automatically dispatched |
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370 | to service a single user request. See |
371 | L<Catalyst::Manual::Tutorial::BasicCRUD|Catalyst::Manual::Tutorial::BasicCRUD> |
372 | and L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained> |
373 | for more information on chained actions. |
374 | |
375 | =back |
376 | |
377 | You should refer to L<Catalyst::Manual::Intro/Action_types> for |
378 | additional information and for coverage of some lesser-used action |
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379 | types not discussed here (C<Regex> and C<LocalRegex>). |
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380 | |
381 | |
382 | =head1 CATALYST VIEWS |
383 | |
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384 | As mentioned in Chapter 2 of the tutorial, views are where you render |
385 | output, typically for display in the user's web browser (but also |
386 | possibly using into output-generation systems, such as PDF or JSON). |
387 | The code in C<lib/MyApp/View> selects the I<type> of view to use, with |
388 | the actual rendering template found in the C<root> directory. As with |
389 | virtually every aspect of Catalyst, options abound when it comes to the |
390 | specific view technology you adopt inside your application. However, |
391 | most Catalyst applications use the Template Toolkit, known as TT (for |
392 | more information on TT, see L<http://www.template-toolkit.org>). Other |
393 | somewhat popular view technologies include Mason |
394 | (L<http://www.masonhq.com> and L<http://www.masonbook.com>) and |
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395 | L<HTML::Template> (L<http://html-template.sourceforge.net>). |
396 | |
397 | |
398 | =head2 Create a Catalyst View |
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399 | |
400 | When using TT for the Catalyst view, there are two main helper scripts: |
401 | |
402 | =over 4 |
403 | |
404 | =item * |
405 | |
406 | L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT> |
407 | |
408 | =item * |
409 | |
410 | L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite> |
411 | |
412 | =back |
413 | |
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414 | Both helpers are similar. C<TT> creates the C<lib/MyApp/View/TT.pm> |
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415 | file and leaves the creation of any hierarchical template organization |
416 | entirely up to you. (It also creates a C<t/view_TT.t> file for testing; |
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417 | test cases will be discussed in Chapter 8.) C<TTSite>, on the other hand, |
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418 | creates a modular and hierarchical view layout with |
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419 | separate Template Toolkit (TT) files for common header and footer |
420 | information, configuration values, a CSS stylesheet, and more. |
421 | |
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422 | While C<TTSite> was useful to bootstrap a project, its use is now |
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423 | deprecated and it should be considered historical. For most Catalyst |
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424 | applications it adds redundant functionality and structure; many in the |
425 | Catalyst community recommend that it's easier to learn both Catalyst and |
426 | Template Toolkit if you use the more basic C<TT> approach. |
427 | Consequently, this tutorial will use "plain old TT." |
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428 | |
429 | Enter the following command to enable the C<TT> style of view |
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430 | rendering for this tutorial: |
431 | |
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432 | $ script/myapp_create.pl view TT TT |
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433 | exists "/home/me/MyApp/script/../lib/MyApp/View" |
434 | exists "/home/me/MyApp/script/../t" |
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435 | created "/home/me/MyApp/script/../lib/MyApp/View/TT.pm" |
436 | created "/home/me/MyApp/script/../t/view_TT.t" |
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437 | |
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438 | This simply creates a view called C<TT> (the second 'TT' argument) in |
439 | a file called C<TT.pm> (the first 'TT' argument). It is now up to you |
440 | to decide how you want to structure your view layout. For the |
441 | tutorial, we will start with a very simple TT template to initially |
442 | demonstrate the concepts, but quickly migrate to a more typical |
443 | "wrapper page" type of configuration (where the "wrapper" controls the |
444 | overall "look and feel" of your site from a single file or set of |
445 | files). |
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446 | |
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447 | Edit C<lib/MyApp/View/TT.pm> and you should see that the default |
448 | contents contains something similar to the following: |
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449 | |
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450 | __PACKAGE__->config(TEMPLATE_EXTENSION => '.tt'); |
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451 | |
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452 | And update it to match: |
453 | |
454 | __PACKAGE__->config( |
455 | # Change default TT extension |
456 | TEMPLATE_EXTENSION => '.tt2', |
457 | # Set the location for TT files |
458 | INCLUDE_PATH => [ |
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459 | MyApp->path_to( 'root', 'src' ), |
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460 | ], |
461 | ); |
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462 | |
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463 | B<NOTE:> Make sure to add a comma after '.tt2' outside the single |
464 | quote. |
465 | |
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466 | This changes the default extension for Template Toolkit from '.tt' to |
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467 | '.tt2' and changes the base directory for your template files from |
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468 | C<root> to C<root/src>. These changes from the default are done mostly |
469 | to facilitate the application we're developing in this tutorial; as with |
470 | most things Perl, there's more than one way to do it... |
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471 | |
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472 | B<Note:> We will use C<root/src> as the base directory for our |
473 | template files, which a full naming convention of |
474 | C<root/src/_controller_name_/_action_name_.tt2>. Another popular option is to |
475 | use C<root/> as the base (with a full filename pattern of |
476 | C<root/_controller_name_/_action_name_.tt2>). |
477 | |
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478 | |
479 | =head2 Create a TT Template Page |
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480 | |
481 | First create a directory for book-related TT templates: |
482 | |
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483 | $ mkdir -p root/src/books |
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484 | |
485 | Then create C<root/src/books/list.tt2> in your editor and enter: |
486 | |
487 | [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%] |
488 | [% # see this "chomping" in your browser because HTML ignores blank lines, but -%] |
489 | [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%] |
490 | [%- # optional, but both the beginning and the ending TT tags support chomping. -%] |
491 | |
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492 | [% # Provide a title -%] |
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493 | [% META title = 'Book List' -%] |
494 | |
495 | <table> |
496 | <tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr> |
497 | [% # Display each book in a table row %] |
498 | [% FOREACH book IN books -%] |
499 | <tr> |
500 | <td>[% book.title %]</td> |
501 | <td>[% book.rating %]</td> |
502 | </tr> |
503 | [% END -%] |
504 | </table> |
505 | |
506 | As indicated by the inline comments above, the C<META title> line uses |
1390ef0e |
507 | TT's META feature to provide a title to the "wrapper" that we will |
508 | create later. Meanwhile, the C<FOREACH> loop iterates through each |
509 | C<book> model object and prints the C<title> and C<rating> fields. |
3533daff |
510 | |
4d63a0d5 |
511 | The C<[%> and C<%]> tags are used to delimit Template Toolkit code. TT |
512 | supports a wide variety of directives for "calling" other files, |
513 | looping, conditional logic, etc. In general, TT simplifies the usual |
514 | range of Perl operators down to the single dot (C<.>) operator. This |
515 | applies to operations as diverse as method calls, hash lookups, and list |
516 | index values (see |
517 | L<http://search.cpan.org/perldoc?Template::Manual::Variables> for |
518 | details and examples). In addition to the usual C<Template> module Pod |
519 | documentation, you can access the TT manual at |
55beb65d |
520 | L<http://search.cpan.org/perldoc?Template::Manual>. |
3533daff |
521 | |
1390ef0e |
522 | B<TIP:> While you can build all sorts of complex logic into your TT |
523 | templates, you should in general keep the "code" part of your templates |
524 | as simple as possible. If you need more complex logic, create helper |
525 | methods in your model that abstract out a set of code into a single call |
526 | from your TT template. (Note that the same is true of your controller |
527 | logic as well -- complex sections of code in your controllers should |
528 | often be pulled out and placed into your model objects.) |
529 | |
530 | |
531 | =head2 Test Run The Application |
532 | |
533 | To test your work so far, first start the development server: |
534 | |
535 | $ script/myapp_server.pl |
536 | |
537 | Then point your browser to L<http://localhost:3000> and you should |
538 | still get the Catalyst welcome page. Next, change the URL in your |
539 | browser to L<http://localhost:3000/books/list>. If you have |
540 | everything working so far, you should see a web page that displays |
541 | nothing other than our column headers for "Title", "Rating", and |
542 | "Author(s)" -- we will not see any books until we get the database and |
543 | model working below. |
544 | |
545 | If you run into problems getting your application to run correctly, it |
546 | might be helpful to refer to some of the debugging techniques covered in |
547 | the L<Debugging|Catalyst::Manual::Tutorial::Debugging> part of the |
548 | tutorial. |
3533daff |
549 | |
550 | |
551 | =head1 CREATE A SQLITE DATABASE |
552 | |
553 | In this step, we make a text file with the required SQL commands to |
1390ef0e |
554 | create a database table and load some sample data. We will use SQLite, |
555 | a popular database that is lightweight and easy to use. Open |
556 | C<myapp01.sql> in your editor and enter: |
3533daff |
557 | |
558 | -- |
559 | -- Create a very simple database to hold book and author information |
560 | -- |
561 | CREATE TABLE books ( |
562 | id INTEGER PRIMARY KEY, |
563 | title TEXT , |
564 | rating INTEGER |
565 | ); |
566 | -- 'book_authors' is a many-to-many join table between books & authors |
567 | CREATE TABLE book_authors ( |
568 | book_id INTEGER, |
569 | author_id INTEGER, |
570 | PRIMARY KEY (book_id, author_id) |
571 | ); |
572 | CREATE TABLE authors ( |
573 | id INTEGER PRIMARY KEY, |
574 | first_name TEXT, |
575 | last_name TEXT |
576 | ); |
577 | --- |
578 | --- Load some sample data |
579 | --- |
580 | INSERT INTO books VALUES (1, 'CCSP SNRS Exam Certification Guide', 5); |
581 | INSERT INTO books VALUES (2, 'TCP/IP Illustrated, Volume 1', 5); |
582 | INSERT INTO books VALUES (3, 'Internetworking with TCP/IP Vol.1', 4); |
583 | INSERT INTO books VALUES (4, 'Perl Cookbook', 5); |
584 | INSERT INTO books VALUES (5, 'Designing with Web Standards', 5); |
585 | INSERT INTO authors VALUES (1, 'Greg', 'Bastien'); |
586 | INSERT INTO authors VALUES (2, 'Sara', 'Nasseh'); |
587 | INSERT INTO authors VALUES (3, 'Christian', 'Degu'); |
588 | INSERT INTO authors VALUES (4, 'Richard', 'Stevens'); |
589 | INSERT INTO authors VALUES (5, 'Douglas', 'Comer'); |
590 | INSERT INTO authors VALUES (6, 'Tom', 'Christiansen'); |
591 | INSERT INTO authors VALUES (7, 'Nathan', 'Torkington'); |
592 | INSERT INTO authors VALUES (8, 'Jeffrey', 'Zeldman'); |
593 | INSERT INTO book_authors VALUES (1, 1); |
594 | INSERT INTO book_authors VALUES (1, 2); |
595 | INSERT INTO book_authors VALUES (1, 3); |
596 | INSERT INTO book_authors VALUES (2, 4); |
597 | INSERT INTO book_authors VALUES (3, 5); |
598 | INSERT INTO book_authors VALUES (4, 6); |
599 | INSERT INTO book_authors VALUES (4, 7); |
600 | INSERT INTO book_authors VALUES (5, 8); |
601 | |
3533daff |
602 | Then use the following command to build a C<myapp.db> SQLite database: |
603 | |
604 | $ sqlite3 myapp.db < myapp01.sql |
605 | |
606 | If you need to create the database more than once, you probably want to |
607 | issue the C<rm myapp.db> command to delete the database before you use |
1390ef0e |
608 | the C<sqlite3 myapp.db E<lt> myapp01.sql> command. |
3533daff |
609 | |
610 | Once the C<myapp.db> database file has been created and initialized, you |
611 | can use the SQLite command line environment to do a quick dump of the |
612 | database contents: |
613 | |
614 | $ sqlite3 myapp.db |
acbd7bdd |
615 | SQLite version 3.5.9 |
3533daff |
616 | Enter ".help" for instructions |
617 | sqlite> select * from books; |
618 | 1|CCSP SNRS Exam Certification Guide|5 |
619 | 2|TCP/IP Illustrated, Volume 1|5 |
620 | 3|Internetworking with TCP/IP Vol.1|4 |
621 | 4|Perl Cookbook|5 |
622 | 5|Designing with Web Standards|5 |
623 | sqlite> .q |
624 | $ |
625 | |
626 | Or: |
627 | |
628 | $ sqlite3 myapp.db "select * from books" |
629 | 1|CCSP SNRS Exam Certification Guide|5 |
630 | 2|TCP/IP Illustrated, Volume 1|5 |
631 | 3|Internetworking with TCP/IP Vol.1|4 |
632 | 4|Perl Cookbook|5 |
633 | 5|Designing with Web Standards|5 |
634 | |
635 | As with most other SQL tools, if you are using the full "interactive" |
636 | environment you need to terminate your SQL commands with a ";" (it's not |
637 | required if you do a single SQL statement on the command line). Use |
638 | ".q" to exit from SQLite from the SQLite interactive mode and return to |
639 | your OS command prompt. |
640 | |
a6d800ac |
641 | For using other databases, such as PostgreSQL or MySQL, see |
642 | L<Appendix 2|Catalyst::Manual::Tutorial::Appendices>. |
3533daff |
643 | |
acbd7bdd |
644 | |
8a472b34 |
645 | =head1 DATABASE ACCESS WITH DBIx::Class |
3533daff |
646 | |
4d63a0d5 |
647 | Catalyst can be used with virtually any form of datastore available via |
648 | Perl. For example, L<Catalyst::Model::DBI|Catalyst::Model::DBI> can be |
649 | used to access databases through the traditional Perl C<DBI> |
650 | interface. However, most Catalyst applications use some form of |
651 | object-relational mapping (ORM) technology to create objects associated |
652 | with tables in a relational database. Although L<Class::DBI|Class::DBI> |
653 | has been a popular choice in the past, Matt Trout's |
654 | L<DBIx::Class|DBIx::Class> (abbreviated as "DBIC") has rapidly emerged |
655 | as the Perl-based ORM technology of choice. Most new Catalyst |
191dee29 |
656 | applications rely on DBIC, as will this tutorial. |
3533daff |
657 | |
3533daff |
658 | |
1390ef0e |
659 | =head2 Create a Dynamic DBIC Model |
660 | |
661 | Use the C<create=dynamic> model helper option to build a model that |
3533daff |
662 | dynamically reads your database structure every time the application |
663 | starts: |
664 | |
4ab6212d |
665 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \ |
666 | create=dynamic dbi:SQLite:myapp.db |
1390ef0e |
667 | exists "/home/me/MyApp/script/../lib/MyApp/Model" |
668 | exists "/home/me/MyApp/script/../t" |
669 | exists "/home/me/MyApp/script/../lib/MyApp" |
670 | created "/home/me/MyApp/script/../lib/MyApp/Schema.pm" |
671 | created "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm" |
672 | created "/home/me/MyApp/script/../t/model_DB.t" |
3533daff |
673 | |
674 | |
1435672d |
675 | The C<script/myapp_create.pl> command breaks down like this: |
676 | |
677 | =over 4 |
678 | |
679 | =item * |
680 | |
d0496197 |
681 | C<DB> is the name of the model class to be created by the helper in |
1435672d |
682 | C<lib/MyApp/Model>. |
683 | |
684 | =item * |
685 | |
686 | C<DBIC::Schema> is the type of the model to create. |
687 | |
688 | =item * |
689 | |
690 | C<MyApp::Schema> is the name of the DBIC schema file written to |
691 | C<lib/MyApp/Schema.pm>. |
692 | |
693 | =item * |
694 | |
695 | Because we specified C<create=dynamic> to the helper, it use |
1390ef0e |
696 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to |
697 | dynamically load the schema information from the database every time |
1435672d |
698 | the application starts. |
699 | |
700 | =item * |
701 | |
702 | And finally, C<dbi:SQLite:myapp.db> is the standard DBI connect string |
703 | for use with SQLite. |
704 | |
705 | =back |
3533daff |
706 | |
d0496197 |
707 | B<NOTE:> Although the C<create=dynamic> option to the DBIC helper |
19c49089 |
708 | makes for a nifty demonstration, is only really suitable for very |
709 | small applications. After this demonstration, you should almost always |
4d63a0d5 |
710 | use the C<create=static> option that we will switch to below. |
dc9a0503 |
711 | |
712 | |
1390ef0e |
713 | =head1 ENABLE THE MODEL IN THE CONTROLLER |
714 | |
acbd7bdd |
715 | Open C<lib/MyApp/Controller/Books.pm> and un-comment the model code we |
716 | left disabled earlier so that your version matches the following (un- |
717 | comment the line containing C<[$c-E<gt>model('DB::Books')-E<gt>all]> |
718 | and delete the next 2 lines): |
1390ef0e |
719 | |
720 | =head2 list |
721 | |
722 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
723 | |
724 | =cut |
725 | |
726 | sub list : Local { |
727 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
728 | # 'Context' that's used to 'glue together' the various components |
729 | # that make up the application |
730 | my ($self, $c) = @_; |
731 | |
732 | # Retrieve all of the book records as book model objects and store in the |
733 | # stash where they can be accessed by the TT template |
734 | $c->stash->{books} = [$c->model('DB::Books')->all]; |
735 | |
736 | # Set the TT template to use. You will almost always want to do this |
737 | # in your action methods (action methods respond to user input in |
738 | # your controllers). |
739 | $c->stash->{template} = 'books/list.tt2'; |
740 | } |
741 | |
1435672d |
742 | B<TIP>: You may see the C<$c-E<gt>model('DB::Books')> un-commented |
743 | above written as C<$c-E<gt>model('DB')-E<gt>resultset('Books')>. The |
c93b5eaa |
744 | two are equivalent. Either way, C<$c-E<gt>model> returns a |
745 | L<DBIx::Class::ResultSet|DBIx::Class::ResultSet> which handles queries |
4d63a0d5 |
746 | against the database and iterating over the set of results that is |
c93b5eaa |
747 | returned. |
748 | |
749 | We are using the C<-E<gt>all> to fetch all of the books. DBIC |
750 | supports a wide variety of more advanced operations to easily do |
751 | things like filtering and sorting the results. For example, the |
518f3851 |
752 | following could be used to sort the results by descending title: |
c93b5eaa |
753 | |
754 | $c->model('DB::Books')->search({}, {order_by => 'title DESC'}); |
755 | |
756 | Some other examples are provided in |
757 | L<DBIx::Class::Manual::Cookbook/Complex WHERE clauses>, with |
758 | additional information found at L<DBIx::Class::ResultSet/search>, |
759 | L<DBIx::Class::Manual::FAQ/Searching>, |
760 | L<DBIx::Class::Manual::Intro|DBIx::Class::Manual::Intro> |
761 | and L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>. |
1390ef0e |
762 | |
763 | |
764 | =head2 Test Run The Application |
3533daff |
765 | |
1435672d |
766 | First, let's enable an environment variable that causes DBIx::Class to |
acbd7bdd |
767 | dump the SQL statements used to access the database. This is a |
1435672d |
768 | helpful trick when you are trying to debug your database-oriented |
769 | code: |
3533daff |
770 | |
771 | $ export DBIC_TRACE=1 |
772 | |
4d63a0d5 |
773 | This assumes you are using bash as your shell -- adjust accordingly if |
3533daff |
774 | you are using a different shell (for example, under tcsh, use |
775 | C<setenv DBIC_TRACE 1>). |
776 | |
d0496197 |
777 | B<NOTE:> You can also set this in your code using |
3533daff |
778 | C<$class-E<gt>storage-E<gt>debug(1);>. See |
779 | L<DBIx::Class::Manual::Troubleshooting> for details (including options |
4d63a0d5 |
780 | to log to a file instead of displaying to the Catalyst development server |
3533daff |
781 | log). |
782 | |
1390ef0e |
783 | Then launch the Catalyst development server. The log output should |
784 | display something like: |
3533daff |
785 | |
acbd7bdd |
786 | $ script/myapp_server.pl |
3533daff |
787 | [debug] Debug messages enabled |
1390ef0e |
788 | [debug] Statistics enabled |
3533daff |
789 | [debug] Loaded plugins: |
790 | .----------------------------------------------------------------------------. |
1390ef0e |
791 | | Catalyst::Plugin::ConfigLoader 0.20 | |
792 | | Catalyst::Plugin::StackTrace 0.08 | |
3533daff |
793 | | Catalyst::Plugin::Static::Simple 0.20 | |
794 | '----------------------------------------------------------------------------' |
795 | |
796 | [debug] Loaded dispatcher "Catalyst::Dispatcher" |
797 | [debug] Loaded engine "Catalyst::Engine::HTTP" |
798 | [debug] Found home "/home/me/MyApp" |
45d511e0 |
799 | [debug] Loaded Config "/home/me/MyApp/myapp.conf" |
3533daff |
800 | [debug] Loaded components: |
801 | .-----------------------------------------------------------------+----------. |
802 | | Class | Type | |
803 | +-----------------------------------------------------------------+----------+ |
804 | | MyApp::Controller::Books | instance | |
805 | | MyApp::Controller::Root | instance | |
d0496197 |
806 | | MyApp::Model::DB | instance | |
807 | | MyApp::Model::DB::Authors | class | |
808 | | MyApp::Model::DB::BookAuthors | class | |
809 | | MyApp::Model::DB::Books | class | |
3533daff |
810 | | MyApp::View::TT | instance | |
811 | '-----------------------------------------------------------------+----------' |
812 | |
813 | [debug] Loaded Private actions: |
814 | .----------------------+--------------------------------------+--------------. |
815 | | Private | Class | Method | |
816 | +----------------------+--------------------------------------+--------------+ |
817 | | /default | MyApp::Controller::Root | default | |
818 | | /end | MyApp::Controller::Root | end | |
1390ef0e |
819 | | /index | MyApp::Controller::Root | index | |
3533daff |
820 | | /books/index | MyApp::Controller::Books | index | |
821 | | /books/list | MyApp::Controller::Books | list | |
822 | '----------------------+--------------------------------------+--------------' |
823 | |
824 | [debug] Loaded Path actions: |
825 | .-------------------------------------+--------------------------------------. |
826 | | Path | Private | |
827 | +-------------------------------------+--------------------------------------+ |
1390ef0e |
828 | | / | /default | |
829 | | / | /index | |
830 | | /books | /books/index | |
3533daff |
831 | | /books/list | /books/list | |
832 | '-------------------------------------+--------------------------------------' |
833 | |
acbd7bdd |
834 | [info] MyApp powered by Catalyst 5.71000 |
835 | You can connect to your server at http://debian:3000 |
3533daff |
836 | |
1390ef0e |
837 | B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from |
838 | the 'base' directory of your application, not inside the C<script> |
839 | directory itself or it will not be able to locate the C<myapp.db> |
840 | database file. You can use a fully qualified or a relative path to |
841 | locate the database file, but we did not specify that when we ran the |
3533daff |
842 | model helper earlier. |
843 | |
844 | Some things you should note in the output above: |
845 | |
846 | =over 4 |
847 | |
1390ef0e |
848 | =item * |
3533daff |
849 | |
1390ef0e |
850 | Catalyst::Model::DBIC::Schema dynamically created three model classes, |
851 | one to represent each of the three tables in our database |
d0496197 |
852 | (C<MyApp::Model::DB::Authors>, C<MyApp::Model::DB::BookAuthors>, |
853 | and C<MyApp::Model::DB::Books>). |
3533daff |
854 | |
1390ef0e |
855 | =item * |
3533daff |
856 | |
857 | The "list" action in our Books controller showed up with a path of |
858 | C</books/list>. |
859 | |
860 | =back |
861 | |
862 | Point your browser to L<http://localhost:3000> and you should still get |
863 | the Catalyst welcome page. |
864 | |
865 | Next, to view the book list, change the URL in your browser to |
866 | L<http://localhost:3000/books/list>. You should get a list of the five |
1390ef0e |
867 | books loaded by the C<myapp01.sql> script above without any formatting. |
868 | The rating for each book should appear on each row, but the "Author(s)" |
191dee29 |
869 | column will still be blank (we will fill that in later). |
3533daff |
870 | |
871 | Also notice in the output of the C<script/myapp_server.pl> that DBIC |
872 | used the following SQL to retrieve the data: |
873 | |
874 | SELECT me.id, me.title, me.rating FROM books me |
875 | |
876 | because we enabled DBIC_TRACE. |
877 | |
0c51850e |
878 | You now have the beginnings of a simple but workable web application. |
3533daff |
879 | Continue on to future sections and we will develop the application |
880 | more fully. |
881 | |
882 | |
1390ef0e |
883 | =head1 CREATE A WRAPPER FOR THE VIEW |
884 | |
acbd7bdd |
885 | When using TT, you can (and should) create a wrapper that will |
1390ef0e |
886 | literally wrap content around each of your templates. This is |
887 | certainly useful as you have one main source for changing things that |
888 | will appear across your entire site/application instead of having to |
889 | edit many individual files. |
890 | |
891 | |
892 | =head2 Configure TT.pm For The Wrapper |
893 | |
894 | In order to create a wrapper, you must first edit your TT view and |
895 | tell it where to find your wrapper file. Your TT view is located in |
896 | C<lib/MyApp/View/TT.pm>. |
897 | |
898 | Edit C<lib/MyApp/View/TT.pm> and change it to match the following: |
899 | |
900 | __PACKAGE__->config( |
901 | # Change default TT extension |
902 | TEMPLATE_EXTENSION => '.tt2', |
903 | # Set the location for TT files |
904 | INCLUDE_PATH => [ |
c2dfb562 |
905 | MyApp->path_to( 'root', 'src' ), |
1390ef0e |
906 | ], |
907 | # Set to 1 for detailed timer stats in your HTML as comments |
908 | TIMER => 0, |
909 | # This is your wrapper template located in the 'root/src' |
910 | WRAPPER => 'wrapper.tt2', |
911 | ); |
912 | |
913 | |
914 | =head2 Create the Wrapper Template File and Stylesheet |
915 | |
916 | Next you need to set up your wrapper template. Basically, you'll want |
917 | to take the overall layout of your site and put it into this file. |
918 | For the tutorial, open C<root/src/wrapper.tt2> and input the following: |
919 | |
920 | <?xml version="1.0" encoding="UTF-8"?> |
921 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> |
922 | <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> |
923 | <head> |
924 | <title>[% template.title or "My Catalyst App!" %]</title> |
925 | <link rel="stylesheet" href="[% c.uri_for('/static/css/main.css') %]" /> |
926 | </head> |
927 | |
928 | <body> |
929 | <div id="outer"> |
930 | <div id="header"> |
931 | [%# Your logo could go here -%] |
932 | <img src="[% c.uri_for('/static/images/btn_88x31_powered.png') %]" /> |
933 | [%# Insert the page title -%] |
934 | <h1>[% template.title or site.title %]</h1> |
935 | </div> |
936 | |
937 | <div id="bodyblock"> |
938 | <div id="menu"> |
939 | Navigation: |
940 | <ul> |
941 | <li><a href="[% c.uri_for('/books/list') %]">Home</a></li> |
942 | <li><a href="[% c.uri_for('/') %]" title="Catalyst Welcome Page">Welcome</a></li> |
1390ef0e |
943 | </ul> |
944 | </div><!-- end menu --> |
945 | |
946 | <div id="content"> |
947 | [%# Status and error messages %] |
948 | <span class="message">[% status_msg %]</span> |
949 | <span class="error">[% error_msg %]</span> |
950 | [%# This is where TT will stick all of your template's contents. -%] |
951 | [% content %] |
952 | </div><!-- end content --> |
953 | </div><!-- end bodyblock --> |
954 | |
955 | <div id="footer">Copyright (c) your name goes here</div> |
c2dfb562 |
956 | </div><!-- end outer --> |
1390ef0e |
957 | |
958 | </body> |
959 | </html> |
960 | |
961 | Notice the status and error message sections in the code above: |
962 | |
963 | <span class="status">[% status_msg %]</span> |
964 | <span class="error">[% error_msg %]</span> |
965 | |
966 | If we set either message in the Catalyst stash (e.g., |
967 | C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it |
968 | will be displayed whenever any view used by that request is rendered. |
969 | The C<message> and C<error> CSS styles can be customized to suit your |
970 | needs in the C<root/static/css/main.css> file we create below. |
971 | |
972 | B<Notes:> |
973 | |
974 | =over 4 |
975 | |
976 | =item * |
977 | |
978 | The Catalyst stash only lasts for a single HTTP request. If |
979 | you need to retain information across requests you can use |
980 | L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use |
4b4d3884 |
981 | Catalyst sessions in the Authentication chapter of the tutorial). |
1390ef0e |
982 | |
983 | =item * |
984 | |
985 | Although it is beyond the scope of this tutorial, you may wish to use |
986 | a JavaScript or AJAX tool such as jQuery (L<http://www.jquery.com>) or |
987 | Dojo (L<http://www.dojotoolkit.org>). |
988 | |
989 | =back |
990 | |
991 | |
992 | =head3 Create A Basic Stylesheet |
993 | |
994 | First create a central location for stylesheets under the static |
995 | directory: |
996 | |
997 | $ mkdir root/static/css |
998 | |
999 | Then open the file C<root/static/css/main.css> (the file referenced in |
1000 | the stylesheet href link of our wrapper above) and add the following |
1001 | content: |
1002 | |
1003 | #header { |
1004 | text-align: center; |
1005 | } |
1006 | #header h1 { |
1007 | margin: 0; |
1008 | } |
1009 | #header img { |
1010 | float: right; |
1011 | } |
1012 | #footer { |
1013 | text-align: center; |
1014 | font-style: italic; |
1015 | padding-top: 20px; |
1016 | } |
1017 | #menu { |
1018 | font-weight: bold; |
1019 | background-color: #ddd; |
1020 | } |
1021 | #menu ul { |
1022 | list-style: none; |
1023 | float: left; |
1024 | margin: 0; |
1025 | padding: 0 0 50% 5px; |
1026 | font-weight: normal; |
1027 | background-color: #ddd; |
1028 | width: 100px; |
1029 | } |
1030 | #content { |
1031 | margin-left: 120px; |
1032 | } |
1033 | .message { |
1034 | color: #390; |
1035 | } |
1036 | .error { |
1037 | color: #f00; |
1038 | } |
1039 | |
1040 | You may wish to check out a "CSS Framework" like Emastic |
1041 | (L<http://code.google.com/p/emastic/>) as a way to quickly |
1042 | provide lots of high-quality CSS functionality. |
1043 | |
1044 | |
1045 | =head2 Test Run The Application |
1046 | |
1047 | Restart the development server and hit "Reload" in your web browser |
1048 | and you should now see a formatted version of our basic book list. |
1049 | Although our wrapper and stylesheet are obviously very simple, you |
1050 | should see how it allows us to control the overall look of an entire |
1051 | website from two central files. To add new pages to the site, just |
1052 | provide a template that fills in the C<content> section of our wrapper |
1053 | template -- the wrapper will provide the overall feel of the page. |
1054 | |
1055 | |
8a472b34 |
1056 | =head1 A STATIC DATABASE MODEL WITH DBIx::Class |
3533daff |
1057 | |
4d63a0d5 |
1058 | First, let's be sure we have a recent version of the DBIC helper, |
4ab6212d |
1059 | L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>, by |
1060 | running this command: |
1061 | |
1062 | $ perl -MCatalyst::Model::DBIC::Schema -e \ |
1063 | 'print "$Catalyst::Model::DBIC::Schema::VERSION\n"' |
1064 | 0.23 |
1065 | |
1066 | If you don't have version 0.23 or higher, please run this command |
1067 | to install it directly from CPAN: |
1068 | |
1069 | $ sudo cpan Catalyst::Model::DBIC::Schema |
1070 | |
1071 | And re-run the version print command to verify that you are now at |
1072 | 0.23 or higher. |
1073 | |
1074 | |
3533daff |
1075 | =head2 Create Static DBIC Schema Files |
1076 | |
1390ef0e |
1077 | Unlike the previous DBIC section where we had C<create=dynamic> |
1078 | automatically discover the structure of the database every time the |
1079 | application started, here we will use static schema files for more |
1080 | control. This is typical of most "real world" applications. |
3533daff |
1081 | |
1390ef0e |
1082 | One option would be to manually create a separate schema file for each |
4d63a0d5 |
1083 | table in the database. However, let's use the same |
1084 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> we used |
1390ef0e |
1085 | earlier with C<create=dynamic> to build the static files for us. |
4d63a0d5 |
1086 | First, let's remove the schema file created earlier: |
3533daff |
1087 | |
1390ef0e |
1088 | $ rm lib/MyApp/Schema.pm |
3533daff |
1089 | |
1090 | Now regenerate the schema using the C<create=static> option: |
1091 | |
4ab6212d |
1092 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \ |
1093 | create=static components=TimeStamp dbi:SQLite:myapp.db |
acbd7bdd |
1094 | exists "/home/me/MyApp/script/../lib/MyApp/Model" |
1095 | exists "/home/me/MyApp/script/../t" |
1096 | Dumping manual schema for MyApp::Schema to directory /home/me/MyApp/script/../lib ... |
3533daff |
1097 | Schema dump completed. |
acbd7bdd |
1098 | exists "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm" |
3533daff |
1099 | |
1390ef0e |
1100 | We could have also deleted C<lib/MyApp/Model/DB.pm>, but it would |
3533daff |
1101 | have regenerated the same file (note the C<exists> in the output above). |
d0496197 |
1102 | If you take a look at C<lib/MyApp/Model/DB.pm>, it simply contains |
1103 | a reference to the actual schema file in C<lib/MyApp/Schema.pm> |
3533daff |
1104 | along with the database connect string. |
1105 | |
1390ef0e |
1106 | If you look in the C<lib/MyApp/Schema.pm> file, you will find that it |
1107 | is no longer using |
1108 | L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> as its base |
1109 | class (L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> is |
1110 | only being used by the helper to load the schema once and then create |
1111 | the static files for us) and C<Schema.pm> only contains a call to the |
4ab6212d |
1112 | C<load_namespaces> method. You will also find that C<lib/MyApp> |
1113 | contains a C<Schema> subdirectory, which then has a subdirectory |
1114 | called "Result". This "Result" subdirectory then has files named |
acbd7bdd |
1115 | according to each of the tables in our simple database (C<Authors.pm>, |
1116 | C<BookAuthors.pm>, and C<Books.pm>). These three files are called |
1117 | "Result Classes" in DBIC nomenclature. Although the Result Class files |
1118 | are named after tables in our database, the classes correspond to the |
1119 | I<row-level data> that is returned by DBIC (more on this later, |
1120 | especially in |
4d63a0d5 |
1121 | L<Catalyst::Manual::Tutorial::BasicCRUD/EXPLORING THE POWER OF DBIC>). |
acbd7bdd |
1122 | |
1123 | The idea with the Result Source files created under |
4ab6212d |
1124 | C<lib/MyApp/Schema/Result> by the C<create=static> option is to only |
1125 | edit the files below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> |
1126 | warning. If you place all of your changes below that point in the |
1127 | file, you can regenerate the automatically created information at the |
1128 | top of each file should your database structure get updated. |
3533daff |
1129 | |
feb4555a |
1130 | Also note the "flow" of the model information across the various files |
1131 | and directories. Catalyst will initially load the model from |
1132 | C<lib/MyApp/Model/DB.pm>. This file contains a reference to |
1133 | C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, the |
4ab6212d |
1134 | call to C<load_namespaces> in C<Schema.pm> will load each of the |
1135 | "Result Class" files from the C<lib/MyApp/Schema/Result> subdirectory. |
1136 | The final outcome is that Catalyst will dynamically create three |
1137 | table-specific Catalyst models every time the application starts (you |
1138 | can see these three model files listed in the debug output generated |
1139 | when you launch the application). |
1140 | |
1141 | B<NOTE:> Older versions of |
1142 | L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> use the |
1143 | deprecated DBIC C<load_classes> technique instead of the newer |
1144 | C<load_namspaces>. For new applications, please try to use |
1145 | C<load_namespaces> since it more easily supports a very useful DBIC |
1146 | technique called "ResultSet Classes." If you need to convert an |
1147 | existing application from "load_classes" to "load_namespaces," you can |
1148 | use this process to automate the migration (but first make sure you |
1149 | have v0.23 C<Catalyst::Model::DBIC::Schema> as discussed above): |
1150 | |
1151 | $ # First delete the existing schema file to disable "compatibility" mode |
1152 | $ rm lib/MyApp/Schema.pm |
1153 | $ |
1154 | $ # Then re-run the helper to build the files for "load_namespaces" |
1155 | $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \ |
1156 | create=static components=TimeStamp dbi:SQLite:myapp.db |
1157 | $ |
1158 | $ # Now convert the existing files over |
1159 | $ cd lib/MyApp/Schema |
1160 | $ perl -MIO::All -e 'for (@ARGV) { my $s < io($_); $s =~ s/.*\n\# You can replace.*?\n//s; |
1161 | $s =~ s/'MyApp::Schema::/'MyApp::Schema::Result::/g; my $d < io("Result/$_"); |
1162 | $d =~ s/1;\n?//; "$d$s" > io("Result/$_"); }' *.pm |
1163 | $ cd ../../.. |
1164 | $ |
1165 | $ # And finally delete the old files |
1166 | $ rm lib/MyApp/Schema/*.pm |
feb4555a |
1167 | |
4ab6212d |
1168 | The "C<perl -MIO::ALL ...>" script will copy all the customized |
1169 | relationship (and other) information below "C<# DO NOT MODIFY>" line |
1170 | from the old files in C<lib/MyApp/Schema> to the new files in |
1171 | C<lib/MyApp/Schema/Result> (we will be starting to add some |
1172 | "customized relationship information in the section below). |
3533daff |
1173 | |
1174 | |
4ab6212d |
1175 | =head2 Updating the Generated DBIC Result Class Files |
3533daff |
1176 | |
acbd7bdd |
1177 | Let's manually add some relationship information to the auto-generated |
1178 | Result Class files. (Note: if you are using a database other than |
1179 | SQLite, such as PostgreSQL, then the relationship could have been |
1180 | automatically placed in the Result Class files. If so, you can skip |
4ab6212d |
1181 | this step.) First edit C<lib/MyApp/Schema/Result/Books.pm> and add the |
acbd7bdd |
1182 | following text below the C<# You can replace this text...> comment: |
3533daff |
1183 | |
1184 | # |
1185 | # Set relationships: |
1390ef0e |
1186 | # |
3533daff |
1187 | |
1188 | # has_many(): |
1189 | # args: |
1190 | # 1) Name of relationship, DBIC will create accessor with this name |
1191 | # 2) Name of the model class referenced by this relationship |
1435672d |
1192 | # 3) Column name in *foreign* table (aka, foreign key in peer table) |
4ab6212d |
1193 | __PACKAGE__->has_many(book_authors => 'MyApp::Schema::Result::BookAuthors', 'book_id'); |
3533daff |
1194 | |
1195 | # many_to_many(): |
1196 | # args: |
1197 | # 1) Name of relationship, DBIC will create accessor with this name |
1390ef0e |
1198 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
1199 | # 3) Name of belongs_to() relationship in model class of has_many() above |
3533daff |
1200 | # You must already have the has_many() defined to use a many_to_many(). |
1201 | __PACKAGE__->many_to_many(authors => 'book_authors', 'author'); |
1202 | |
1203 | |
1204 | B<Note:> Be careful to put this code I<above> the C<1;> at the end of the |
1205 | file. As with any Perl package, we need to end the last line with |
1206 | a statement that evaluates to C<true>. This is customarily done with |
1207 | C<1;> on a line by itself. |
1208 | |
acbd7bdd |
1209 | C<Important Note:> Although this tutorial uses plural names for both |
1210 | the names of the SQL tables and therefore the Result Classes (after |
1211 | all, C<Schema::Loader> automatically named the Result Classes from the |
1212 | names of the SQL tables it found), DBIC users prefer singular names |
1213 | for these items. B<Please try to use singular table and DBIC |
1214 | model/Result Class names in your applications.> This tutorial will |
1215 | migrate to singular names as soon as possible (patches welcomed). |
1216 | B<Note that while singular is preferred for the DBIC model, plural is |
1217 | perfectly acceptable for the names of the controller classes.> After |
1218 | all, the C<Books.pm> controller operates on multiple books. |
1219 | |
1390ef0e |
1220 | This code defines both a C<has_many> and a C<many_to_many> relationship. |
1221 | The C<many_to_many> relationship is optional, but it makes it easier to |
1222 | map a book to its collection of authors. Without it, we would have to |
1223 | "walk" though the C<book_authors> table as in |
1224 | C<$book-E<gt>book_authors-E<gt>first-E<gt>author-E<gt>last_name> |
1225 | (we will see examples on how to use DBIC objects in your code soon, |
1226 | but note that because C<$book-E<gt>book_authors> can return multiple |
1227 | authors, we have to use C<first> to display a single author). |
1228 | C<many_to_many> allows us to use the shorter |
1229 | C<$book-E<gt>authors-E<gt>first-E<gt>last_name>. |
1230 | Note that you cannot define a C<many_to_many> relationship without |
1231 | also having the C<has_many> relationship in place. |
3533daff |
1232 | |
4ab6212d |
1233 | Then edit C<lib/MyApp/Schema/Result/Authors.pm> and add relationship |
3533daff |
1234 | information as follows (again, be careful to put in above the C<1;> but |
1235 | below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> comment): |
1236 | |
1237 | # |
1238 | # Set relationships: |
1239 | # |
1240 | |
1241 | # has_many(): |
1242 | # args: |
4d63a0d5 |
1243 | # 1) Name of relationship, DBIC will create an accessor with this name |
3533daff |
1244 | # 2) Name of the model class referenced by this relationship |
1435672d |
1245 | # 3) Column name in *foreign* table (aka, foreign key in peer table) |
4ab6212d |
1246 | __PACKAGE__->has_many(book_author => 'MyApp::Schema::Result::BookAuthors', 'author_id'); |
3533daff |
1247 | |
1248 | # many_to_many(): |
1249 | # args: |
1250 | # 1) Name of relationship, DBIC will create accessor with this name |
1251 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
1390ef0e |
1252 | # 3) Name of belongs_to() relationship in model class of has_many() above |
3533daff |
1253 | # You must already have the has_many() defined to use a many_to_many(). |
1254 | __PACKAGE__->many_to_many(books => 'book_author', 'book'); |
1255 | |
1390ef0e |
1256 | Finally, do the same for the "join table," |
4ab6212d |
1257 | C<lib/MyApp/Schema/Result/BookAuthors.pm>: |
3533daff |
1258 | |
1259 | # |
1260 | # Set relationships: |
1261 | # |
1262 | |
1263 | # belongs_to(): |
1264 | # args: |
1265 | # 1) Name of relationship, DBIC will create accessor with this name |
1266 | # 2) Name of the model class referenced by this relationship |
1267 | # 3) Column name in *this* table |
4ab6212d |
1268 | __PACKAGE__->belongs_to(book => 'MyApp::Schema::Result::Books', 'book_id'); |
3533daff |
1269 | |
1270 | # belongs_to(): |
1271 | # args: |
1272 | # 1) Name of relationship, DBIC will create accessor with this name |
1273 | # 2) Name of the model class referenced by this relationship |
1274 | # 3) Column name in *this* table |
4ab6212d |
1275 | __PACKAGE__->belongs_to(author => 'MyApp::Schema::Result::Authors', 'author_id'); |
3533daff |
1276 | |
1277 | |
1390ef0e |
1278 | =head2 Run The Application |
3533daff |
1279 | |
4d63a0d5 |
1280 | Run the Catalyst development server script with the C<DBIC_TRACE> option |
1281 | (it might still be enabled from earlier in the tutorial, but here is an |
1282 | alternate way to specify the option just in case): |
3533daff |
1283 | |
1284 | $ DBIC_TRACE=1 script/myapp_server.pl |
1285 | |
1390ef0e |
1286 | Make sure that the application loads correctly and that you see the |
1287 | three dynamically created model class (one for each of the |
4ab6212d |
1288 | Result Classes we created). |
3533daff |
1289 | |
acbd7bdd |
1290 | Then hit the URL L<http://localhost:3000/books/list> with your browser |
1291 | and be sure that the book list is displayed via the relationships |
1292 | established above. You can leave the development server running for |
1293 | the next step if you wish. |
3533daff |
1294 | |
c2dfb562 |
1295 | B<Note:> You will not see the authors yet because the view does not yet |
1296 | use the new relations. Read on to the next section where we update the |
1297 | template to do that. |
3533daff |
1298 | |
1299 | |
1300 | =head1 UPDATING THE VIEW |
1301 | |
acbd7bdd |
1302 | Let's add a new column to our book list page that takes advantage of |
1303 | the relationship information we manually added to our schema files in |
4d63a0d5 |
1304 | the previous section. Edit C<root/src/books/list.tt2> and add the |
acbd7bdd |
1305 | following code below the existing table cell that contains |
1306 | C<book.rating> (IOW, add a new table cell below the existing two |
1307 | C<E<lt>tdE<gt>> tags but above the closing C<E<lt>/trE<gt>> and |
1308 | C<E<lt>/tableE<gt>> tags): |
3533daff |
1309 | |
acbd7bdd |
1310 | ... |
3533daff |
1311 | <td> |
1312 | [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%] |
1313 | [% # loop in 'side effect notation' to load just the last names of the -%] |
a0c5188a |
1314 | [% # authors into the list. Note that the 'push' TT vmethod does not print -%] |
3533daff |
1315 | [% # a value, so nothing will be printed here. But, if you have something -%] |
1316 | [% # in TT that does return a method and you don't want it printed, you -%] |
1317 | [% # can: 1) assign it to a bogus value, or 2) use the CALL keyword to -%] |
1318 | [% # call it and discard the return value. -%] |
1319 | [% tt_authors = [ ]; |
1320 | tt_authors.push(author.last_name) FOREACH author = book.authors %] |
1321 | [% # Now use a TT 'virtual method' to display the author count in parens -%] |
1322 | [% # Note the use of the TT filter "| html" to escape dangerous characters -%] |
1323 | ([% tt_authors.size | html %]) |
1324 | [% # Use another TT vmethod to join & print the names & comma separators -%] |
1325 | [% tt_authors.join(', ') | html %] |
1326 | </td> |
acbd7bdd |
1327 | ... |
3533daff |
1328 | |
1390ef0e |
1329 | Then hit "Reload" in your browser (note that you don't need to reload |
3533daff |
1330 | the development server or use the C<-r> option when updating TT |
1390ef0e |
1331 | templates) and you should now see the number of authors each book has |
1332 | along with a comma-separated list of the authors' last names. (If you |
1333 | didn't leave the development server running from the previous step, |
1334 | you will obviously need to start it before you can refresh your |
1335 | browser window.) |
1336 | |
1337 | If you are still running the development server with C<DBIC_TRACE> |
1338 | enabled, you should also now see five more C<SELECT> statements in the |
1339 | debug output (one for each book as the authors are being retrieved by |
acbd7bdd |
1340 | DBIC): |
3533daff |
1341 | |
c2dfb562 |
1342 | SELECT me.id, me.title, me.rating FROM books me: |
acbd7bdd |
1343 | SELECT author.id, author.first_name, author.last_name FROM book_authors me |
1344 | JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '1' |
1345 | SELECT author.id, author.first_name, author.last_name FROM book_authors me |
1346 | JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '2' |
1347 | SELECT author.id, author.first_name, author.last_name FROM book_authors me |
1348 | JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '3' |
1349 | SELECT author.id, author.first_name, author.last_name FROM book_authors me |
1350 | JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '4' |
1351 | SELECT author.id, author.first_name, author.last_name FROM book_authors me |
1352 | JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '5' |
c2dfb562 |
1353 | |
1354 | Also note in C<root/src/books/list.tt2> that we are using "| html", a |
1355 | type of TT filter, to escape characters such as E<lt> and E<gt> to < |
1356 | and > and avoid various types of dangerous hacks against your |
1357 | application. In a real application, you would probably want to put |
1358 | "| html" at the end of every field where a user has control over the |
1359 | information that can appear in that field (and can therefore inject |
1360 | markup or code if you don't "neutralize" those fields). In addition to |
1361 | "| html", Template Toolkit has a variety of other useful filters that |
1362 | can found in the documentation for |
1363 | L<Template::Filters|Template::Filters>. |
3533daff |
1364 | |
1365 | |
1390ef0e |
1366 | =head1 RUNNING THE APPLICATION FROM THE COMMAND LINE |
1367 | |
1368 | In some situations, it can be useful to run your application and |
1369 | display a page without using a browser. Catalyst lets you do this |
1370 | using the C<scripts/myapp_test.pl> script. Just supply the URL you |
1371 | wish to display and it will run that request through the normal |
1372 | controller dispatch logic and use the appropriate view to render the |
1373 | output (obviously, complex pages may dump a lot of text to your |
1374 | terminal window). For example, if you type: |
1375 | |
1376 | $ script/myapp_test.pl "/books/list" |
1377 | |
1378 | You should get the same text as if you visited |
1379 | L<http://localhost:3000/books/list> with the normal development server |
1380 | and asked your browser to view the page source. |
3533daff |
1381 | |
1390ef0e |
1382 | |
1383 | =head1 OPTIONAL INFORMATION |
1384 | |
4b4d3884 |
1385 | B<NOTE: The rest of this chapter of the tutorial is optional. You can |
1386 | skip to Chapter 4, L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>, |
3533daff |
1387 | if you wish.> |
1388 | |
acbd7bdd |
1389 | |
8a472b34 |
1390 | =head2 Using 'RenderView' for the Default View |
1390ef0e |
1391 | |
1392 | Once your controller logic has processed the request from a user, it |
1393 | forwards processing to your view in order to generate the appropriate |
3533daff |
1394 | response output. Catalyst uses |
1390ef0e |
1395 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by |
4d63a0d5 |
1396 | default to automatically perform this operation. If you look in |
1390ef0e |
1397 | C<lib/MyApp/Controller/Root.pm>, you should see the empty |
3533daff |
1398 | definition for the C<sub end> method: |
1399 | |
1400 | sub end : ActionClass('RenderView') {} |
1401 | |
1390ef0e |
1402 | The following bullet points provide a quick overview of the |
3533daff |
1403 | C<RenderView> process: |
1404 | |
1405 | =over 4 |
1406 | |
1407 | =item * |
1408 | |
1409 | C<Root.pm> is designed to hold application-wide logic. |
1410 | |
1411 | =item * |
1412 | |
1390ef0e |
1413 | At the end of a given user request, Catalyst will call the most specific |
1414 | C<end> method that's appropriate. For example, if the controller for a |
1415 | request has an C<end> method defined, it will be called. However, if |
1416 | the controller does not define a controller-specific C<end> method, the |
3533daff |
1417 | "global" C<end> method in C<Root.pm> will be called. |
1418 | |
1419 | =item * |
1420 | |
1421 | Because the definition includes an C<ActionClass> attribute, the |
1422 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic |
1423 | will be executed B<after> any code inside the definition of C<sub end> |
1424 | is run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions> |
1425 | for more information on C<ActionClass>. |
1426 | |
1427 | =item * |
1428 | |
1390ef0e |
1429 | Because C<sub end> is empty, this effectively just runs the default |
1430 | logic in C<RenderView>. However, you can easily extend the |
1431 | C<RenderView> logic by adding your own code inside the empty method body |
1432 | (C<{}>) created by the Catalyst Helpers when we first ran the |
1433 | C<catalyst.pl> to initialize our application. See |
1434 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more |
4d63a0d5 |
1435 | detailed information on how to extend C<RenderView> in C<sub end>. |
3533daff |
1436 | |
1437 | =back |
1438 | |
1439 | |
1440 | =head2 Using The Default Template Name |
1441 | |
1390ef0e |
1442 | By default, C<Catalyst::View::TT> will look for a template that uses the |
1443 | same name as your controller action, allowing you to save the step of |
1444 | manually specifying the template name in each action. For example, this |
1445 | would allow us to remove the |
1446 | C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our |
1447 | C<list> action in the Books controller. Open |
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1448 | C<lib/MyApp/Controller/Books.pm> in your editor and comment out this line |
1449 | to match the following (only the C<$c-E<gt>stash-E<gt>{template}> line |
1450 | has changed): |
1451 | |
1452 | =head2 list |
1453 | |
1454 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
1455 | |
1456 | =cut |
1457 | |
1458 | sub list : Local { |
1459 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
1460 | # 'Context' that's used to 'glue together' the various components |
1461 | # that make up the application |
1462 | my ($self, $c) = @_; |
1463 | |
1464 | # Retrieve all of the book records as book model objects and store in the |
1465 | # stash where they can be accessed by the TT template |
d0496197 |
1466 | $c->stash->{books} = [$c->model('DB::Books')->all]; |
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1467 | |
1468 | # Set the TT template to use. You will almost always want to do this |
1469 | # in your action methods (actions methods respond to user input in |
1470 | # your controllers). |
1471 | #$c->stash->{template} = 'books/list.tt2'; |
1472 | } |
1473 | |
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1474 | |
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1475 | You should now be able to restart the development server as per the |
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1476 | previous section and access the L<http://localhost:3000/books/list> |
1477 | as before. |
1478 | |
1479 | B<NOTE:> Please note that if you use the default template technique, |
1480 | you will B<not> be able to use either the C<$c-E<gt>forward> or |
4b4d3884 |
1481 | the C<$c-E<gt>detach> mechanisms (these are discussed in Chapter 2 and |
1482 | Chapter 9 of the Tutorial). |
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1483 | |
1484 | |
4d63a0d5 |
1485 | =head2 Return To A Manually Specified Template |
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1486 | |
1487 | In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach> |
1488 | later in the tutorial, you should remove the comment from the |
1489 | statement in C<sub list> in C<lib/MyApp/Controller/Books.pm>: |
1490 | |
1491 | $c->stash->{template} = 'books/list.tt2'; |
1492 | |
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1493 | Then delete the C<TEMPLATE_EXTENSION> line in |
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1494 | C<lib/MyApp/View/TT.pm>. |
1495 | |
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1496 | You should then be able to restart the development server and |
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1497 | access L<http://localhost:3000/books/list> in the same manner as |
1498 | with earlier sections. |
1499 | |
1500 | |
1501 | =head1 AUTHOR |
1502 | |
1503 | Kennedy Clark, C<hkclark@gmail.com> |
1504 | |
1505 | Please report any errors, issues or suggestions to the author. The |
1506 | most recent version of the Catalyst Tutorial can be found at |
82ab4bbf |
1507 | L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>. |
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1508 | |
45c7830f |
1509 | Copyright 2006-2008, Kennedy Clark, under Creative Commons License |
8482d557 |
1510 | (L<http://creativecommons.org/licenses/by-sa/3.0/us/>). |