Chris Winters > Workflow-0.17 > Workflow::Condition

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Module Version: 1.04   Source   Latest Release: Workflow-1.41

NAME ^

Workflow::Condition - Evaluate a condition depending on the workflow state and environment

SYNOPSIS ^

 # First declare the condition in a 'workflow_condition.xml'...
 
 <conditions>
   <condition
      name="IsAdminUser"
      class="MyApp::Condition::IsAdminUser">
         <param name="admin_group_id" value="5" />
         <param name="admin_group_id" value="6" />
   </condition>
 ...
 
 # Reference the condition in an action...
 <actions>
    <action name="MyAction" class="My::Action">
      ... 
      <condition name="IsAdminUser" />
    </action>
 ...
  
 # Then implement the condition
 
 package MyApp::Condition::IsAdminUser;
 
 use strict;
 use base qw( Workflow::Condition );
 use Workflow::Exception qw( condition_error configuration_error );
 
 __PACKAGE__->mk_accessors( 'admin_group_id' );
 
 sub _init {
     my ( $self, $params ) = @_;
     unless ( $params->{admin_group_id} ) {
         configuration_error
             "You must define one or more values for 'admin_group_id' in ",
             "declaration of condition ", $self->name;
     }
     my @admin_ids = $self->_normalize_array( $params->{admin_group_id} );
     $self->admin_group_id( { map { $_ => 1 } @admin_ids } );
 }
 
 sub evaluate {
     my ( $self, $wf ) = @_;
     my $admin_ids = $self->admin_group_id;
     my $current_user = $wf->context->param( 'current_user' );
     unless ( $current_user ) {
         condition_error "No user defined, cannot check groups";
     }
     foreach my $group ( @{ $current_user->get_groups } ) {
         return if ( $admin_ids->{ $group->id } );
     }
     condition_error "Not member of any Admin groups";
 }

DESCRIPTION ^

Conditions are used by the workflow to see whether actions are available in a particular context. So if user A asks the workflow for the available actions she might get a different answer than user B since they determine separate contexts.

SUBCLASSING ^

Strategy

The idea behind conditions is that they can be stateless. So when the Workflow::Factory object reads in the condition configuration it creates the condition objects and initializes them with whatever information is passed in.

Then when the condition is evaluated we just call evaluate() on the condition. Hopefully the operation can be done very quickly since the condition may be called many, many times during a workflow lifecycle -- they are typically used to show users what options they have given the current state of the workflow for things like menu options. So keep it short!

Methods

To create your own condition you should implement the following:

_init( \%params )

This is optional, but called when the condition is first initialized. It may contain information you will want to initialize your condition with in \%params, which are all the declared parameters in the condition declartion except for 'class' and 'name'.

You may also do any initialization here -- you can fetch data from the database and store it in the class or object, whatever you need.

If you do not have sufficient information in \%params you should throw an exception (preferably 'configuration_error' imported from Workflow::Exception).

evaluate( $workflow )

Determine whether your condition fails by throwing an exception. You can get the application context information necessary to process your condition from the $workflow object.

COPYRIGHT ^

Copyright (c) 2003-2004 Chris Winters. All rights reserved.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

AUTHORS ^

Chris Winters <chris@cwinters.com>

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