1Catalyst::Manual::TutorUisaelr::C0o1n_tIrnitbruot(e3d)PCeartlalDyosctu:m:eMnatnautailo:n:Tutorial::01_Intro(3)
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NAME

6       Catalyst::Manual::Tutorial::01_Intro - Catalyst Tutorial - Chapter 1:
7       Introduction
8

OVERVIEW

10       This is Chapter 1 of 10 for the Catalyst tutorial.
11
12       Tutorial Overview
13
14       1.  01_Introduction
15
16       2.  Catalyst Basics
17
18       3.  More Catalyst Basics
19
20       4.  Basic CRUD
21
22       5.  Authentication
23
24       6.  Authorization
25
26       7.  Debugging
27
28       8.  Testing
29
30       9.  Advanced CRUD
31
32       10. Appendices
33

DESCRIPTION

35       This tutorial provides a multi-part introduction to the Catalyst Web
36       Framework. It seeks to provide a rapid overview of many of its most
37       commonly used features. The focus is on the real-world best practices
38       required in the construction of nearly all Catalyst applications.
39
40       Although the primary target of the tutorial is users new to the
41       Catalyst framework, experienced users may wish to review specific
42       sections (for example, how to use DBIC for their model classes, how to
43       add authentication and authorization to an existing application, and/or
44       form management).
45
46       The most recent code for the tutorial is included on the Tutorial
47       Virtual Machine you can download from:
48
49       <http://cattut.shadowcat.co.uk/>
50
51       See "STARTING WITH THE TUTORIAL VIRTUAL MACHINE" below for instructions
52       getting and using the VM.
53
54       Should you wish to download the code directly, you get pull it via the
55       following command (note: will probably be switching to git soon):
56
57           svn co http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/Tutorial/ CatalystTutorial
58
59       This will download the most recent code for each chapter of the
60       tutorial into the CatalystTutorial directory on your machine.
61
62       These reference implementations are provided so that when you follow
63       the tutorial, you can use the code to ensure that your system is set up
64       correctly (which shouldn't be an issue if you use the Tutorial Virtual
65       Machine), :-) and that you have not inadvertently made any typographic
66       errors, or accidentally skipped part of the tutorial.
67
68       NOTE: You can use any Perl-supported OS and environment to run
69       Catalyst. It should make little or no difference to Catalyst's
70       operation, but this tutorial has been written using the Debian-based
71       Tutorial Virtual Machine that you can download and use to work through
72       the full tutorial step by step.  WE STRONGLY RECOMMEND THAT YOU USE THE
73       VIRTUAL MACHINE IMAGE TO WORK THROUGH THE TUTORIAL to avoid issues that
74       may crop up if you are working with a different configuration.  We have
75       tested the Tutorial Virtual Machine to make sure all of the examples
76       work correctly, but it is hard to guarantee this on other platforms and
77       versions.
78
79       If you would prefer to install directly from CPAN and not use the
80       Tutorial Virtual machine, you can download the example program and all
81       the necessary dependencies to your local machine by installing the
82       Task::Catalyst::Tutorial distribution:
83
84            cpan Task::Catalyst::Tutorial
85
86       This will also test to make sure the dependencies are working.  If you
87       have trouble installing these, please ask for help on the #catalyst IRC
88       channel, or the Catalyst mailing list.
89
90       Subjects covered by the tutorial include:
91
92       •   A simple application that lists and adds books.
93
94       •   The use of DBIx::Class (DBIC) for the model (including some of the
95           more advanced techniques you will probably want to use in your
96           applications).
97
98       •   How to write CRUD (Create, Read, Update, and Delete) operations in
99           Catalyst.
100
101       •   Authentication ("auth").
102
103       •   Role-based authorization ("authz").
104
105       •   Attempts to provide an example showing current (5.9) Catalyst
106           practices.
107
108       •   The use of Template Toolkit (TT).
109
110       •   Useful techniques for troubleshooting and debugging Catalyst
111           applications.
112
113       •   The use of SQLite as a database (with code also provided for MySQL
114           and PostgreSQL).  (Note: Because we make use of the DBIx::Class
115           Object Relational Mapping [ORM] layer, out our application will be
116           database agnostic and can easily be used by any of the databases
117           supported by DBIx::Class.)
118
119       •   The use of HTML::FormFu or HTML::FormHandler for automated form
120           processing and validation.
121
122       This tutorial makes the learning process its main priority.  For
123       example, the level of comments in the code found here would likely be
124       considered excessive in a "normal project."  Because of their
125       contextual value, this tutorial will generally favor inline comments
126       over a separate discussion in the text.  It also deliberately tries to
127       demonstrate multiple approaches to various features (in general, you
128       should try to be as consistent as possible with your own production
129       code).
130
131       Furthermore, this tutorial tries to minimize the number of controllers,
132       models, TT templates, and database tables.  Although this does result
133       in things being a bit contrived at times, the concepts should be
134       applicable to more complex environments.  More complete and complicated
135       example applications can be found at
136       <http://wiki.catalystframework.org/wiki/resources/catalystexamples> and
137       in the "examples" area of the Catalyst Subversion repository at
138       <http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/>.
139

STARTING WITH THE TUTORIAL VIRTUAL MACHINE

141       The steps below briefly outline how you can download the Tutorial
142       Virtual Machine.  This document uses the term "host machine" to refer
143       to the physical machine where you will run the virtualization software
144       and boot up the VM.  The terms "guest machine" or just "VM" refer to
145       the virtual machine itself -- the thing where you actually do the
146       tutorial (and that you boot up on the "host machine").
147
148       Note: Throughout the tutorial, we will shows the UNIX shell prompt as
149       ""$"".  If you are using the Tutorial VM, the prompt will really be
150       ""catalyst@catalyst:~$"" (where ""~"" will change to show your current
151       directory), but we will keep it short and just use ""$"".
152
153       1.  Download a Tutorial Virtual Machine image from
154           <http://cattut.shadowcat.co.uk/>
155
156           A big thanks to Shadowcat Systems for hosting the virtual machines
157           (and everything else they do for the Perl community)!
158
159       2.  Uncompress the image on the "host machine":
160
161               MAINCOMPUTER:~$ tar zxvf CatalystTutorial.tgz
162
163       3.  Boot the virtual machine using a tool like VMWare Player
164           <https://www.vmware.com/products/workstation-player.html> or
165           VirtualBox <https://www.virtualbox.org/>.
166
167       4.  Once you get a login prompt, enter the username catalyst and a
168           password for "catalyst".  You should now be at a prompt that looks
169           like:
170
171               catalyst login: catalyst
172               Password: catalyst
173               ...
174               catalyst@catalyst:~$
175
176       5.  Type ""ifconfig"" to get the IP address assigned to the virtual
177           machine.  You should get output along the lines of:
178
179               eth0  Link encap:Ethernet  HWaddr 00:01:22:3b:45:69
180                     inet addr:192.168.0.12  Bcast:192.168.0.255  Mask:255.255.255.0
181               ...
182
183           You want the IP address on the second line below the "eth0"
184           interface.  The image is designed to automatically use a DHCP-
185           assigned address.
186
187           Try to ping this IP address from your "host machine" (main
188           desktop):
189
190               MAINCOMPUTER:~$ ping 192.168.0.12
191               PING 192.168.0.12 (192.168.0.12) 56(84) bytes of data.
192               64 bytes from 192.168.0.12: icmp_req=1 ttl=255 time=4.97 ms
193               64 bytes from 192.168.0.12: icmp_req=2 ttl=255 time=3.43 ms
194               ...
195
196           Note: The ping above is being originated from your host machine
197           (main desktop) and going to your guest virtual machine, not the
198           other way around.
199
200           If you are not seeing a valid IP address or it's not responding to
201           pings (for example, you get error messages along the lines of
202           "Request timed out", "100% packet loss", or "Destination Host
203           Unreachable"), there could be a few network-related issues you
204           might need to sort out.  See the section below "Sorting Out Virtual
205           Machine Network-Related Issues" for additional information and
206           troubleshooting advice.
207
208           Note: Remember this IP address... you will be using it throughout
209           the tutorial.
210
211       6.  From your main desktop machine, open an SSH client and connect to
212           the IP address found in the previous step.  You should get a login
213           prompt (accept the SSH key if you get a warning message about
214           that).  Login with the same username and password as we used in
215           Step 4: catalyst / catalyst
216
217               catalyst login: catalyst
218               Password: catalyst
219               ...
220               catalyst@catalyst:~$
221
222       7.  Using the SSH session, change to the sample code directory for
223           Chapter 3 included with the Tutorial Virtual Machine and start the
224           Catalyst Development Server:
225
226               $ cd Final/Chapter03/MyApp
227               $ perl script/myapp_server.pl
228
229       8.  From your main desktop machine (the "host machine"), open a web
230           browser and go to http://A.B.C.D:3000/, where "A.B.C.D" is the IP
231           address to your virtual machine that you looked up in Step 5.  For
232           example, if your virtual machine is using the IP address
233           192.168.0.12, you would put the following URL into your web
234           browser:
235
236               http://192.168.0.12:3000/
237
238           Make sure you don't forget the :3000 to use port 3000 instead of
239           the usual port 80 that is used by HTTP by default.
240
241           You should get a Catalyst Welcome Screen.  If you do, feel free to
242           jump right in to Chapter 2 of the tutorial.  If you don't go get
243           the Catalyst Welcome Screen, go back and carefully check each of
244           the steps above.
245
246       9.  Optional: Also, to reduce download size, the Tutorial VM just
247           includes a minimal command-line environment.  You are free to use
248           Debian's very capable "apt" package manager to install other
249           packages.  You will first want to pull the apt cache files with
250           "aptitude update" (or "apt-get update" if you prefer apt-get).
251
252           The VI/VIM editor is already installed on the Tutorial Virtual
253           Machine.  In order to reduce the size of the download, Emacs is not
254           pre-installed.  Since people obviously have very strong opinions
255           about which editor is best, :-) fortunately it's very easy to
256           install Emacs:
257
258               $ sudo aptitude update
259               $ sudo aptitude install emacs
260
261           In general, it is expected that people will boot up the Tutorial VM
262           on their main desktop (the "host machine" using the terminology
263           above) and then use that main desktop machine to SSH and web browse
264           into the "guest VM" as they work through the tutorial.  If you wish
265           to install X Windows (or any other packages), just use the
266           "aptitude" (or "apt-get") Debian commands.
267
268           For example, to install X Windows with Fluxbox (a lightweight
269           WindowManager -- it is great for things like this tutorial since
270           it's about 1/10th the size of other common X Windows environments),
271           you can do:
272
273               $ sudo aptitude update
274               $ sudo aptitude install xorg fluxbox iceweasel
275
276           And then start X Windows from the VM Console with this command:
277
278               $ startx
279
280           Note that if you want to start Fluxbox from an SSH session, you can
281           use the "sudo dpkg-reconfigure x11-common" and select "anybody"
282           from the menu.  Otherwise, you will need to be on the actual "VM
283           console" to start it.
284
285           If you have a preference for the Gnome desktop environment, you can
286           do:
287
288               $ sudo aptitude update
289               $ sudo aptitude install gnome iceweasel
290               $
291               $ # You can reboot or start with 'startx', we will just reboot here
292               $ reboot
293
294           For KDE, just substitute the package name ""kde"" for ""gnome""
295           above.
296
297               $ sudo aptitude install kde iceweasel
298
299           Note that "iceweasel" is basically used to install Firefox on
300           Debian boxes.  You can start it under X Windows with either the
301           "firefox" command or the "iceweasel" command (or use the menus).
302           You can get more information on Iceweasel at
303           <https://wiki.debian.org/Iceweasel>.
304
305           Also, you might need to add more memory to your virtual machine if
306           you want to run X Windows (or other tools that might require
307           additional memory).  Consult the documentation of your
308           virtualization software for instructions on how to do this (it's
309           usually pretty simple).
310
311       You may note that the Tutorial Virtual Machine uses local::lib so that
312       the Perl modules are run from ~/perl5 (in this case,
313       /home/catalyst/perl5) vs. the usual location of your "system Perl".  We
314       recommend that you also consider using this very handy module.  It can
315       greatly ease the process of maintaining and testing different
316       combinations or Perl modules across development, staging, and
317       production servers.  (The "relocatable Perl" feature can also be used
318       to run both the modules and Perl itself from your home directory [or
319       any other directory you chose]).
320
321       Note: Please provide feedback on how the Virtual Machine approach for
322       the tutorial works for you.  If you have suggestions or comments, you
323       can reach the author through the email address at the bottom of this
324       page or via an RT ticket at
325       <https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
326
327   Sorting Out Virtual Machine Network-Related Issues
328       In general, using a virtual machine to work through the tutorial is
329       *much* easier than trying to do it in other environments, especially if
330       you are new to Catalyst (or Perl or CPAN or ...).  However, it's
331       possible that you could run into a few network-related issues.  The
332       good news is that there is lots of information about the issue
333       available via search engines on the Internet.  Here is some background
334       information to get you started.
335
336       In Step 5 of the prior section above, we assumed that a "Bridged Mode"
337       configuration and DHCP will work (it should for most people).  If DHCP
338       is not working or is not available in your location, most virtual
339       machine "host" environments let you select between one of several
340       different types of networking between the "guest" and the "host"
341       machine.
342
343           1) Bridged
344           2) NAT
345           3) Local host only
346
347       The Tutorial Virtual Machine defaults to "Bridged" -- this should
348       result in the VM acting like another device on your network that will
349       get a different DHCP IP address than the host machine.  The advantage
350       of this approach, is that you can easily SSH and web browse to the
351       guest virtual machine.  In general, this is the best option if you want
352       to be able to boot up the VM and then use your SSH client and web
353       browser from your main machine to connect into the virtual machine.
354
355       In some environments, you might have better luck with "NAT" (Network
356       Address Translation) mode.  With this configuration, the guest VM
357       shares the same IP address as the host machine.  The downside of this
358       approach is that special configuration is required if you want to be
359       able to SSH or web browse to the guest VM.  The NAT option should
360       automatically allow the VM "outbound connection" (e.g., to the Internet
361       if you want to install additional Debian packages), but it requires
362       special configuration if you want to get "inbound connections" that go
363       from some other machine (including the "host machine") into the VM.
364       Some virtual machine host environments let you configure a "static NAT"
365       or "port forwarding" to reach the guest OS, but others omit this
366       functionality.
367
368       Note: NAT mode can work fine if you install X Windows and do the whole
369       tutorial locally on the actual VM vs. using SSH and a web browser from
370       your host machine.
371
372       "Local host only" mode let's the guest VM and the host machine talk on
373       a "private subnet" that other devices in your network cannot reach.
374       This can work as long as you don't need to go from the VM to the
375       Internet (for example, to install other Debian packages).
376
377       Consult the documentation on your virtual machine host environment for
378       help configuring the options above.  Here are some links that might
379       help:
380
381       •   <https://web.archive.org/web/20160623183717/http://vmfaq.com/index.php?View=entry&EntryID=34>
382
383       •   <https://www.vmware.com/support/pubs/player_pubs.html>
384
385       •   <https://www.virtualbox.org/manual/ch06.html>
386

VERSIONS AND CONVENTIONS USED IN THIS TUTORIAL

388       This tutorial was built using the following resources. Please note that
389       you may need to make adjustments for different environments and
390       versions (note that trailing zeros in version numbers are not
391       significant and may get dropped with some techniques for viewing them;
392       for example, Catalyst v5.80020 might show up as 5.8002):
393
394       •   Debian 6 (Squeeze)
395
396       •   Catalyst v5.90002
397
398       •   Catalyst::Devel v1.34
399
400       •   DBIx::Class v0.08195
401
402       •   Catalyst::Model::DBIC::Schema v0.54
403
404       •   Template Toolkit v2.22
405
406       •   HTML::FormFu -- v0.09004
407
408NOTE: You can check the versions you have installed with the
409           following command (note the slash before the space):
410
411               perl -M<_mod_name_>\ 999
412
413           or:
414
415               perl -M<_mod_name_> -e 'print "$<_mod_name_>::VERSION\n"'
416
417           For example:
418
419               perl -MCatalyst::Devel\ 999
420
421           or:
422
423               perl -MCatalyst::Devel -e 'print "$Catalyst::Devel::VERSION\n";'
424
425       •   This tutorial will show URLs in the format of
426           "http://localhost:3000", but if you are running your web browser
427           from outside the Tutorial Virtual Machine, you will want to
428           substitute the IP address of your VM for the "localhost" in the
429           URLs (again, you can get the IP address for eth0 from the
430           "ifconfig" command).  For example, if your VM has an IP address of
431           192.168.0.12, you will want to use a base URL of
432           "http://192.168.0.12:3000".  Note that the development server
433           defaults to port 3000 (you can change with the "-p" option on the
434           command line).
435
436           Please Note: Depending on the web browser you are using, you might
437           need to hit "Shift+Reload" or "Ctrl+Reload" to pull a fresh page
438           when testing your application at various points (see
439           <https://en.wikipedia.org/wiki/Wikipedia:Bypass_your_cache> for a
440           comprehensive list of options for each browser).
441
442           Also, the "-k" keepalive option to the development server can be
443           necessary with some browsers (especially Internet Explorer).
444

DATABASES

446       This tutorial will primarily focus on SQLite because of its simplicity
447       of installation and use; however, modifications in the script required
448       to support MySQL and PostgreSQL will be presented in the Appendix.
449
450       Note: One of the advantages of using tools like Catalyst and DBIC is
451       that applications become much more database independent.  As such, you
452       will notice that only the ".sql" files used to initialize the database
453       change between database systems: most of the code generally remains the
454       same.
455
456       You can jump to the next chapter of the tutorial here: Catalyst Basics
457

AUTHOR

459       Kennedy Clark, "hkclark@gmail.com"
460
461       Feel free to contact the author for any errors or suggestions, but the
462       best way to report issues is via the CPAN RT Bug system at
463       <https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
464
465       Copyright 2006-2011, Kennedy Clark, under the Creative Commons
466       Attribution Share-Alike License Version 3.0
467       (<https://creativecommons.org/licenses/by-sa/3.0/us/>).
468
469
470
471perl v5.34.0                      2021-0C7a-t2a2lyst::Manual::Tutorial::01_Intro(3)
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