+
+=head1 NAME
+
+Apache::MVC - Web front end to a data source
+
+=head1 SYNOPSIS
+
+ package BeerDB;
+ use base 'Apache::MVC';
+ sub handler { Apache::MVC::handler("BeerDB", @_) }
+ BeerDB->set_database("dbi:mysql:beerdb");
+ BeerDB->config->{uri_base} = "http://your.site/";
+ BeerDB->config->{display_tables} = [qw[beer brewery pub style]];
+ # Now set up your database:
+ # has-a relationships
+ # untaint columns
+
+ 1;
+
+=head1 DESCRIPTION
+
+A large number of web programming tasks follow the same sort of pattern:
+we have some data in a datasource, typically a relational database. We
+have a bunch of templates provided by web designers. We have a number of
+things we want to be able to do with the database - create, add, edit,
+delete records, view records, run searches, and so on. We have a web
+server which provides input from the user about what to do. Something in
+the middle takes the input, grabs the relevant rows from the database,
+performs the action, constructs a page, and spits it out.
+
+This module aims to be the most generic and extensible "something in the
+middle".
+
+An example would help explain this best. You need to add a product
+catalogue to a company's web site. Users need to list the products in
+various categories, view a page on each product with its photo and
+pricing information and so on, and there needs to be a back-end where
+sales staff can add new lines, change prices, and delete out of date
+records. So, you set up the database, provide some default templates
+for the designers to customize, and then write an Apache handler like
+this:
+
+ package ProductDatabase;
+ use base 'Apache::MVC';
+ __PACKAGE__->set_database("dbi:mysql:products");
+ BeerDB->config->{uri_base} = "http://your.site/catalogue/";
+ ProductDatabase::Product->has_a("category" => ProductDatabase::Category);
+ # ...
+
+ sub authenticate {
+ my ($self, $request) = @_;
+ return OK if $request->{ar}->get_remote_host() eq "sales.yourcorp.com";
+ return OK if $request->{action} =~ /^(view|list)$/;
+ return DECLINED;
+ }
+ 1;
+
+You then put the following in your Apache config:
+
+ <Location /catalogue>
+ SetHandler perl-script
+ PerlHandler ProductDatabase
+ </Location>
+
+And copy the templates found in F<templates/factory> into the
+F<catalogue/factory> directory off the web root. When the designers get
+back to you with custom templates, they are to go in
+F<catalogue/custom>. If you need to do override templates on a
+database-table-by-table basis, put the new template in
+F<catalogue/I<table>>.
+
+This will automatically give you C<add>, C<edit>, C<list>, C<view> and
+C<delete> commands; for instance, a product list, go to
+
+ http://your.site/catalogue/product/list
+
+For a full example, see the included "beer database" application.
+
+=head1 HOW IT WORKS
+
+There's some documentation for the workflow in L<Apache::MVC::Workflow>,
+but the basic idea is that a URL part like C<product/list> gets
+translated into a call to C<ProductDatabase::Product-E<gt>list>. This
+propagates the request with a set of objects from the database, and then
+calls the C<list> template; first, a C<product/list> template if it
+exists, then the C<custom/list> and finally C<factory/list>.
+
+If there's another action you want the system to do, you need to either
+subclass the model class, and configure your class slightly differently:
+
+ package ProductDatabase::Model;
+ use base 'Apache::MVC::Model::CDBI';
+
+ sub supersearch :Exported {
+ my ($self, $request) = @_;
+ # Do stuff, get a bunch of objects back
+ $r->objects(\@objects);
+ $r->template("template_name");
+ }
+
+ ProductDatabase->config->{model_class} = "ProductDatabase::Model";
+
+(The C<:Exported> attribute means that the method can be called via the
+URL C</I<table>/supersearch/...>.)
+
+Alternatively, you can put the method directly into the specific model
+class for the table:
+
+ sub ProductDatabase::Product::supersearch :Exported { ... }
+
+By default, the view class uses Template Toolkit as the template
+processor, and the model class uses C<Class::DBI>; it may help you to be
+familiar with these modules before going much further with this,
+although I expect there to be other subclasses for other templating
+systems and database abstraction layers as time goes on. The article at
+C<http://www.perl.com/pub/a/2003/07/15/nocode.html> is a great
+introduction to the process we're trying to automate.
+
+=head1 AUTHOR
+
+Simon Cozens, C<simon@cpan.org>
+
+=head1 LICENSE
+
+You may distribute this code under the same terms as Perl itself.