CGI::Path - module to aid in traversing one or more paths
CGI::Path allows for easy navigation through a set of steps, a path. It uses a session extensively (managed by default via Apache::Session) to hopefully simplify path based cgis.
A path is a package, like CGI::Path::Skel. The path needs to be @ISA CGI::Path. The package can contain the step methods as described below. You can also make a directory for the path, like CGI/Path/Skel, where the direectory will contain a package for each step. This could be done from your $ENV{PERL5LIB}.
The path_hash is what helps generate the path_array, which is just an array of steps. It is a hash to allow for easy overrides, since it is sort of hard to override the third element of an array through a series of news.
The path_hash needs a key named 'initial_step', and then steps that point down the line, like so
path_hash => {
initial_step => 'page_one',
page_one => 'page_two',
page_two => 'page_three',
},
since page_three doesn't point anywhere, the path_array ends. You can just override $self->path_hash, and have it return a hash ref as above.
It is quite easy to look at $ENV{PATH_INFO} and control multiple paths through a single cgi. I offer the following as a simple example
sub path_hash { my $self = shift; my $sub_path = ''; if($ENV{PATH_INFO} && $ENV{PATH_INFO} =~ m@/(\w+)@) { $sub_path = $1; } my $sub_path_hash = { '' => { initial_step => 'main', main => '', }, };
### this is the generic path for adding something
if($sub_path =~ /^add_(\w+)$/ && !exists $sub_path_hash->{$sub_path}) {
$sub_path_hash->{$sub_path} = {
initial_step => $sub_path,
$sub_path => "${sub_path}_confirm",
"${sub_path}_confirm" => "${sub_path}_receipt",
};
}
$sub_path = '' unless(exists $sub_path_hash->{$sub_path});
return $sub_path_hash->{$sub_path};
}
The above path_hash method was used to manage a series of distinct add paths. Distinct paths added users, categories, blogs and entries. Each path was to handled differently, but they each had a path similar to the add_user path, which looked like this
add_user => add_user_confirm => add_user_receipt
my_module by default is something like CGI::Path::Skel. You can override $self->my_module and have it return a scalar containing your my_module. Module overrides are done based on my_module.
my_module by default is something like path/skel. It defaults to a variant of my_module. You can override $self->my_content and have it return a scalar your my_content. html content gets printed based on my_content.
The path_array is formed from path_hash. It is an array ref of the steps in the path.
$self->navigate walks through a path of steps, where each step corresponds to a .htm content file and a .val validation hash.
A step corresponds to a .htm content file. The .htm and .val need to share the base same name.
$self->{this_step} is hash ref containing the following previous_step => the last step this_step => the current step validate_ref => the validation ref for the current step
Generally, navigate generates the form (see below), and for each step does the following
-- Get the validate ref (val_ref) for the given page -- Comparing the val_ref to the form see if info exists for the step -- Validate according to the val_ref -- If validation fails, or if info doesn't exist, process the page and stop
More specifically, the following methods can be called for a step, in the given order.
step details/possible uses --------------------------------------------- ${step}_hook_pre initializations, must return 0 or step gets skipped info_exists checks to see if you have info for this step ${step}_info_complete can be used to make sure you have all the info you need
validate contains the following
${step}_pre_validate stuff to check before validate proper
validate_proper runs the .val file validation
${step}_post_validate stuff to run after validate proper
${step}_hash_fill return a hash ref of things to add to $self->fill
fill is a hash ref of what fills the forms
${step}_hash_form perhaps set stuff for $self->{my_form}
my_form is a hash ref that gets passed to the process method
${step}_hash_errors set errors
${step}_step do actual stuff for the step
${step}_hook_post last chance
The goal is that the programmer just look at $self->form for form or session information. To help facilitate this goal, I use the following
$self->this_form - form from the current hit
$self->{session_only} = [] - things that get deleted from this_form and get inserted from the session
$self->{session_wins} = [] - this_form wins by default, set this if you want something just from the session
The code then sets the form with the following line
$self->{form} = {%{$self->session}, %{$this_form}, %{$form}};
magic_fill is written to help aid in rapid development. It is a simple, space-delimited file of key/value pairs, like so
address 123 Fake Street email,email_address,from cpan@spack.net
I split on the first white space, then split on commas for the key names. In the above example, I would end up with a ref like this
{
address => '123 Fake Street',
email => 'cpan@spack.net',
email_address => 'cpan@spack.net',
from => 'cpan@spack.net',
}
Once I have a ref, those values will get filled into forms as pages are displayed. Makes it nice to fill forms with dummy data and test the flow of your script.
magic_fill is turned off by default. The method allow_magic_fill determines if magic_fill is on. By default allow_magic_fill just looks at $self->{allow_magic_fill} and returns true or false accordingly. magic_fill_filename points to the location of your file.
When you new up your CGI::Path object you just need to do something like the following
my $self = CGI::Path->new({ allow_magic_fill => 1, magic_fill_filename => "/path/to/magic_fill_file", });
You can use variable values using the magic_fill_interpolation_hash. By default you can use Template::Toolkit tags, like so
currenttime [% localtime %]
Currently, the following are included by default in the magic_fill_interpolation_hash
script - a good guess at the name of your script _script - the stuff after the last _ in the above script localtime - scalar (localtime), time - time,
I also include %ENV
Two other keys are not available by default, based on micro seconds namely
micro - join(".", &Time::HiRes::gettimeofday()), which really tries to get you a unique value
micro_part - (&Time::HiRes::gettimeofday())[1];, which is just the micro seconds
To make these swaps available you need to set $self->{allow_magic_micro} to a true value.
CGI::Path uses Apache::Session::File by default for session management. If you use this default you will need to write the following methods
session_dir - returns the directory where the session files will go session_lock_dir - returns the directory where the session lock files will go
Copyright 2003-2004, Earl J. Cahill. All rights reserved.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
Address bug reports and comments to: cpan@spack.net.
When sending bug reports, please provide the version of CGI::Path, the version of Perl, and the name and version of the operating system you are using.
