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Passing data around within CGI::Prototype

by lhoward (Vicar)
on Mar 16, 2006 at 16:21 UTC ( #537190=perlquestion: print w/ replies, xml ) Need Help??
lhoward has asked for the wisdom of the Perl Monks concerning the following question:

I am writing my first application with CGI::Prototype. I am trying to use the "call yourself until the form in right, and once its ok send you over to the you_did_it_right page" approach shown in Merlyn's Introduction to CGI::Prototype (part 2) article. I am getting hung up about how to pass data between slots (either within one package or between different packages).

I am doing most of my heavy lifting in the respond slot (is this where I am going wrong?). If there are errors in the form submission, I want to include some helpful text about what the problems were and display it in the template when I redisplay the form. Similarly, I want to do some computations on the submitted data in the respond slot and then use the results of that computation (which may be as simple as a scalar, or could be a more complicated datastructure) in the current (or another) package's template.

The best method that I have found so far is to add slots in app_enter to hold the values I want to pass around. However, I can't help but think there is a better way to approach this issue. I have a simplified example (written from my head, so it my be a little off) that shows this approach.

Package Foo; use base CGI::Prototype; sub app_enter { my $self = shift; $self->reflect->addSlots([qw(result FIELD)] => ''); } sub respond { my $self = shift; if(($self->param('num')) && ($self->param('num')=~/^\d+$/){ $self->result = $param('num')%2 ? 'odd' : 'even'; } return $self; } sub template { my $self = shift; return \ << "END_OF_TEMPLATE" ; [% self.CGI.header %]<html><head></head><body> [% IF self.result %] [% self.param('num') %] is [% self.result %] <br> [% END %] Please enter an integer: [% self.CGI.start_form; self.CGI.textfield('num'); self.CGI.submit; self.CGI.end_form %] </body></html> END_OF_TEMPLATE } 1;
Am I trying to force CGI::Prototype to work the way I want to work when instead I should be freeing my mind and working with it the way it wants to be used? How should I be going about passing my data around within the application?


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Re: Passing data around within CGI::Prototype
by cbrandtbuffalo (Deacon) on Mar 16, 2006 at 17:40 UTC
    We do something similar, with a little more structure. We have a parent class that all apps inherit from, and in that class we do something like this:
    __PACKAGE__->reflect->addSlot( tt_data => {}, perl_data => {}, );
    This creates empty data slots that you can use as a sort of data store. In our code, we can then do things like this:
    $self->perl_data->{pass_around} = 'some calculated data'; $self->tt_data->{some_stuff} = $self->get_some_stuff(); if ( $self->perl_data->{pass_around} ){ blah
    This is basically a simple way to create object data that can be accessed from anywhere without having to pass it. We use separate structures for perl_data and tt_data as an internal standard. Data for the template goes in tt_data and internal data is in perl_data.

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