Models and Views don't usually have access to the request object, since
they probably don't really need it. Sometimes, however, having the request
context available outside of Controllers makes your application cleaner.
If that's the case, just use this module as a base class:

package MyApp::Model::Foobar;
use base qw|Catalyst::Component::ACCEPT_CONTEXT Catalyst::Model|;

Then, you'll be able to get the current request object from within your
model:

sub do_something {
my $self = shift;
print "The current URL is ". $self->context->req->uri->as_string;
}