Where to place a dispatch table in MVC? - perl

Question

A dispatch table (or dispatch method) is both a table (model) and a router/controller.
Imagine a tabbed navigation where there may be 30 tabs for various end users. Each tab is essentially a page that has its own controller and views. In my case, a dispatch table contains keys for the tabs and then data for each tab (path, displayName, visibility, etc).
my $tabs = {
Home => {
action => \&HomeController::dashboard,
displayName => ‘Home’,
...
},
About => {
action => \&AboutController::info,
displayName => ‘About Us’,
...
},
...
};
Initially I had a TabController and TabView. Inside the controller was a dispatch table; however it didn’t seem to fall in accordance with MVC. It seemed fine when there was only 3 tabs, but different when it grew, especially as it required security trimming or filtering the views.
It made sense to move it to the model since it was being treated more as a data table. However, because it’s Perl (and a dispatch table) all the corresponding packages must also be loaded. So this TabModel is loading many controllers (and in some cases views). I don’t particularly like to load/reference any controllers in the model, so loading multi feels even worse.
Is there a best practice or example for this scenario?
Addendum
In an attempt to provide something a little more tangible. I'm going to attempt to frame this around a makeshift web application. This is only a conceptual example, not fully-working and missing a lot; but hopefully should add a little more description and context. It has the following, directory structure:
index.pl -- entrance
Controllers/
-- Dashboard.pm
-- Home.pm
-- About.pm
Models/
-- Tabs.pm
-- Users.pm
Views/
-- Dashboard.pm
-- Home.pm
-- About.pm
-- Error.pm
I won't break out index.pl, but it essentially parses parameters and directs to the DashboardController::dashboard.
DashboardController
package Controllers::Dashboard;
sub dashboard{
my $users = Models::Users::get_all(); # Users Model
my $tabs = Models::Tabs::get_permitted( # Tabs Model
$users->{CURRENT_USER}{permissions}
);
print Views::Page::render($users,$tabs); # Page View
}
AboutController
package Controllers::About;
sub info {
# No models necessary
print Views::About::render();
}
TabsModel
package Models::Tabs;
use Controllers::Home;
use Controllers::About;
sub get_all {
my $tabs = {
Home => {
action => \&Controllers::Dashboard::dashboard,
displayName => ‘Home’,
...
},
About => {
action => \&Controllers::About::info,
displayName => ‘About Us’,
...
},
...
};
return $tabs;
}
sub get_permitted {
my $user_permissions = shift;
my $tabs = get_all();
if (defined $user_permissions){
foreach my $tab (keys %$tabs){
delete $tabs->{$tab} unless $user_permissions->{"can_access_$tab"};
}
}
}
DashboardView
package Views::Dashboard;
sub render {
my ($users,$tabs) = #_;
my $html_tabs = '<ul>';
foreach my $tab (values %$tabs){
$html_tabs .= "$tab->{displayName}";
}
$html_tabs .= '</ul>;
my $html = <<"END";
$html_tabs
<!-- dashboard content -->
END
return $html;
}

Answer 1

ancient question, but it popped up in the feed today
I think there's something wonky in the way you've categorized things. Models are typically sources of data and don't really care what you do with them or how you display them. However, you've pushed some of the view (presentation) into the model. To me, that Tabs.pm looks like it should be part of some view.
And, because a dispatch table is a table doesn't mean it's a source of data. It's a particular technique to solve a problem that's not related to the particular data or the particular view. If you did the same task without the dispatch table, you wouldn't suddenly move that responsibility into another part of MVC.