How to create a simple Web application with Web::App Template::Toolkit and Class::DBI

1. How to create a simple Web application with Web::App Template::Toolkit and Class::DBI Leonard Miller June 17, 2008

2. Who is this talk for?

3. Who is this talk for? • Need to write web applications

4. Who is this talk for? • Need to write web applications • Don’t want/cannot have a heavy framework

5. Who is this talk for? • Need to write web applications • Don’t want/cannot have a heavy framework • Experienced Programmers.

6. Who is this talk for? • Need to write web applications • Don’t want/cannot have a heavy framework • Experienced Programmers. • Know about CPAN, how to learn from CPAN’s documentation.

7. Who is this talk for? • Need to write web applications • Don’t want/cannot have a heavy framework • Experienced Programmers. • Know about CPAN, how to learn from CPAN’s documentation. • Newer programmers that could use a new/better way to organize their code.

8. Why these three Modules? • Separate out the code to MVC Pieces • Each can be used/tested alone • The modules themselves are easy to use and understand

9. Why not Catalyst? • mod_perl/fastcgi: You don’t always have the access on the machine to get Catalyst to work. • CGI::Application is a ‘lite’ framework, and as such is much smaller. • Not as big and scary. • Trivial to install in a local ~/lib dir

10. What is MVC • MVC stands for Model-View-Controller

11. What is MVC • MVC breaks the work into three parts

12. What is MVC • MVC breaks the work into three parts • Model - Short for database model. Class::DBI does all the database work: inserts/queries.

13. What is MVC • MVC breaks the work into three parts • Model - Short for database model. Class::DBI does all the database work: inserts/queries. • View - Template::Toolkit does all the view/html work.

14. What is MVC • MVC breaks the work into three parts • Model - Short for database model. Class::DBI does all the database work: inserts/queries. • View - Template::Toolkit does all the view/html work. • Controller - CGI::Application holds all the logic to glue the Model and the View together.

15. What is MVC • Who has seen code like this: use DBI; my $sql = "select * from users"; my $dbh = DBI->connect( $ds, $un, $pw ); my $sth = $dbh->prepare($sql); $sth->execute(); print "Content-type: text/html\r\n\r\n"; while (my $h = $sth->fetchrow_hashref()) { print ”Name is:".$h->{'first_name'}."<br>\n"; }

16. What is MVC • Who has seen code like this: my $q = new CGI; if ($q-> param('first_name' eq ''){ print input_form(); } else{ my $sql = "insert into users ..."; my $sth = $dbh->prepare($sql); $sth->execute(); print submission_form(); }

17. What is MVC • Any questions regarding what MVC is?

18. CGI::Application • A sample program • Helloworld.cgi <- config info • HelloWorldCgiApp.pm <- controller • Html files: <- View • header.html • body.html • footer.html • MyDatabase.pm <- Model

19. CGI::Application helloworld.cgi: use HelloWorldCgiApp; my $helloworld = HelloWorldCgiApp->new(); $helloworld->run();

20. CGI::Application helloworld.cgi (with config info): use HelloWorldCgiApp; my $helloworld = HelloWorldCgiApp->new ( PARAMS => { tt_config => { INCLUDE_PATH => ".", PRE_PROCESS => 'header.html', POST_PROCESS => 'footer.html', }, hw_string => "hi there big earth!", }, ); $helloworld->run();

21. CGI::Application HelloWorldCgiApp (continued): package HelloWorldCgiApp; use base 'CGI::Application'; use Template; sub setup { my $self = shift; $self->run_modes( 'mode1' => 'start’, 'mode2' => 'sec_page' ); $self->start_mode('mode1'); }

22. CGI::Application $q -> param (‘rm’); HelloWorldCgiApp (continued): package HelloWorldCgiApp; use base 'CGI::Application'; use Template; sub setup { my $self = shift; $self->run_modes( 'mode1' => 'start’, 'mode2' => 'sec_page' ); $self->start_mode('mode1'); }

23. CGI::Application HelloWorldCgiApp (continued): sub start { my $self = shift; my $tt_config = $self->param(‘tt_config’) my $tt = Template->new( $tt_config ); $tt->process('body.html', { hwstr => 'hi big planet!!!', }, \$html); return $html; }

24. CGI::Application HelloWorldCgiApp (continued): sub cgiapp_prerun { my ($self, $runmode) = @_; my $q = $self->query; }

25. Class::DBI • The mysql table: CREATE TABLE users ( user_id INT NOT NULL PRIMARY KEY AUTO_INCREMENT, first_name varchar(75) NOT NULL, last_name varchar(75) NOT NULL, country_code CHAR(2) NULL );

26. Class::DBI MyDatabase.pm: package MyDatabase; use base 'Class::DBI'; MyDatabase->connection('dbi:mysql:db',‘user’,’pw'); MyDatabase -> table('users'); MyDatabase -> columns( All => qw/user_id first_name last_name country_code / ); MyDatabase -> columns( Primary => user_id );

27. Class::DBI • Using the Class::DBI Module HelloWorldCgiApp.pm: use MyDatabase; my @users = MyDatabase -> retrieve_all; $tt->process('body.html', { users => [ @users ], }, \$html);

28. Class::DBI • Using the Module use MyDatabase; my @users = MyDatabase -> retrieve_all; my $user = MyDatabase -> retrieve( 1 ); $tt->process('body.html', { users => [ @users ], user => $user, }, \$html);

29. Class::DBI • Using the Module – inserts: use MyDatabase; my $user = MyDatabase -> insert( { first_name => ‘Randall’, last_name => ‘Schwartz’, country_code => ‘US’, } );

30. Template::Toolkit • Why use Template::Toolkit? • Common ‘look and feel’ templates. • Easy to change for those people who are better at design than we are. • What type of data is It good for? • arrays • hashes • scalars

31. Template::Toolkit • Any html file is a TT file! • Simplest usage for a scalar: <html> <body> [% var_name %] </body> </html>

32. Template::Toolkit • Usage for an Array where users is an array: <body> [% FOREACH item IN users %] [% item %]<br /> [% END %] </body>

33. Template::Toolkit • Usage for an Array where users is a hash: <body> [%item.user_id%] [%item.first_name%] [%item.last_name%] [%item.country_code%] <br /> </body>

34. Template::Toolkit • Usage for an Array where users is an array of hashes (like an array of rows from a database): <body> [% FOREACH item IN users %] [%item.user_id%] [%item.first_name%] [%item.last_name%] [%item.country_code%]<br /> [% END %] </body>

35. Template::Toolkit • Usage for an Array where users is an array of hashes (like an array of rows from a database): <body> <form> <input type=“hidden” name=“rm” value=“page_2” [% FOREACH item IN users %] ... [% END %] <input type=“submit”> </form> </body>

36. Questions?

37. Thank you Leonard Miller June 17, 2008