how to create a simple web application with web::app template::toolkit and class::dbi

How to create a simple Web application with Web::App

Template::Toolkit and Class::DBI

Leonard MillerJune 17, 2008

Who is this talk for?


• Need to write web applications



• Don’t want/cannot have a heavy framework




• Experienced Programmers.




• Experienced Programmers.

• Know about CPAN, how to learn from CPAN’s documentation.


• 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.

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

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

What is MVC

• MVC stands for Model-View-Controller

What is MVC

• MVC breaks the work into three parts

What is MVC

• MVC breaks the work into three parts1. Model - Short for database model.

Class::DBI does all the database work: inserts/queries.

What is MVC



2. View - Template::Toolkit does all the view/html work.

What is MVC



2. View - Template::Toolkit does all the view/html work.

3. Controller - CGI::Application holds all the logic to glue the Model and the View together.

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";}

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();}

What is MVC

• Any questions regarding what MVC is?

CGI::Application• A sample program• Helloworld.cgi <- config info• HelloWorldCgiApp.pm <- controller• Html files: <- View

– header.html– body.html– footer.html

• MyDatabase.pm <- Model

CGI::Applicationhelloworld.cgi:

use HelloWorldCgiApp;

my $helloworld = HelloWorldCgiApp->new();

$helloworld->run();

CGI::Applicationhelloworld.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();

CGI::ApplicationHelloWorldCgiApp (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');

}


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');

}

$q -> param (‘rm’);


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;

}


sub cgiapp_prerun

{

my ($self, $runmode) = @_;

my $q = $self->query;

}

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

);

Class::DBIMyDatabase.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 );

Class::DBI• Using the Class::DBI ModuleHelloWorldCgiApp.pm:

use MyDatabase;

my @users = MyDatabase -> retrieve_all;

$tt->process('body.html',

{

users => [ @users ],

},

\$html);

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);

Class::DBI

• Using the Module – inserts:

use MyDatabase;

my $user = MyDatabase -> insert(

{

first_name => ‘Randall’,

last_name => ‘Schwartz’,

country_code => ‘US’,

}

);

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

Template::Toolkit

• Any html file is a TT file!

• Simplest usage for a scalar:<html>

<body>

[% var_name %]

</body>

</html>

Template::Toolkit

• Usage for an Array where users is an array:

<body>

[% FOREACH item IN users %]

[% item %]<br />

[% END %]

</body>

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>

Template::Toolkit

• Usage for an Array where users is an array of hashes (like an array of rows from a database):

<body>


[%item.user_id%] [%item.first_name%]

[%item.last_name%] [%item.country_code%]<br />

[% END %]

</body>

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”


...

[% END %]

<input type=“submit”>

</form>

</body>

Questions?

Thank you

Leonard MillerJune 17, 2008

how to create a simple web application with web::app template::toolkit and class::dbi

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