On Tue, 2005-01-04 at 00:14 +0000, Tony Bowden wrote:
> On Mon, Jan 03, 2005 at 06:21:14PM -0500, Perrin Harkins wrote:
> > I structure my web applications so that common code can be added to all
> > requests in a central place (some kind of common "setup" hook). I
> > usually put my $tt->process inside of some wrapper function as well,
> > since I want it to be a singleton.
>
> Care to share an example?
Using something like CGI::Application does provide an easy place to put
common code. When I use it, I make a base class that contains my common
setup code.
I've also rolled my own controller many times, and in those I typically
have a base class with a run() method that wraps the request handler in
an eval block and deals with logging errors. That's a place to put
common code, or I might divide it further with subclasses
(My::Controller subclassed by My::Controller::Protected or some such).
At the end of a request, I will call a template wrapper method something
like this (the "P3" namespace is for Plus Three, my employer):
sub process_template {
# this is a class method, not an object method!
my $class = shift;
my %args = @_;
# add in the config object
my $config = P3::Model::Config->new();
$args{'DATA'}->{'config'} = $config->view();
# put in the escaping functions
$args{'DATA'}->{'html'} = \&Apache::Util::escape_html;
$args{'DATA'}->{'url'} = \&Apache::Util::escape_uri;
my $output;
my $template_path = $class->template_path();
# Add document root to include path
push @{$template_path}, P3::Util->get_request()->document_root();
my $te = P3::Util->get_template({
INCLUDE_PATH => $template_path,
});
my $rc = $te->process($args{'TEMPLATE'},
$args{'DATA'},
\$output);
unless ($rc) {
# Handle TT error. This is supposed to be a Template::Error
# object, but is actually a string in some cases.
my $error = $te->error();
my $error_text = (ref($error) ? $error->as_string() : $error);
throw P3::Error::System::Template(-text => $error_text);
}
$class->send_page(\$output);
}
The send_page() method deals with setting Content-Length, Last-Modified,
etc. get_template() just grabs a cached TT object (or creates a new one
if there isn't one cached) and sets INCLUDE_PATH on it. Note that
P3::Model::Config is always added to provide access to some common
values, and this is the sort of thing I was suggesting to do with the
data that started this thread. I also use the mod_perl escaping
functions because they're very fast.
Here's an example of how this all fits together, from the synopsis:
In httpd.conf:
<Location /foo>
SetHandler perl-script
PerlHandler P3::Control::Foo->run
</Location>
In P3::Control::Foo:
package P3::Control::Foo;
use strict;
use base qw(P3::Control);
sub handler {
my $class = shift;
# do some work
$class->process_template(
TEMPLATE => 'foo.html',
DATA => \%view_data,
);
}
sub last_modified {
# override parent class
return time;
}
These days, I am using CGI::Application to do this kind of thing, just
because it has convenient hooks for Data::FormValidator and
HTML::FillInForm. I'm keeping a close eye on OpenInteract2 though.
Just need to test out how well it deals with using Class::DBI instead of
SPOPS.
- Perrin
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