NAME

Workflow::Validator - Ensure data are valid

SYNOPSIS

# First declare the validator...
<validator name="DateValidator"
           class="MyApp::Validator::Date">
  <param name="date_format" value="%Y-%m-%d %h:%m"/>
</validator>

# Then associate the validator with runtime data from the context...
<action name="MyAction">
   <validator name="DateValidator">
      <arg>$due_date</arg>
   </validator>
</action>

# TODO: You can also inintialize and instantiate in one step if you
# don't need to centralize or reuse (does this work?)

<action name="MyAction">
   <validator class="MyApp::Validator::Date">
      <param name="date_format" value="%Y-%m-%d %h:%m"/>
      <arg>$due_date</arg>
   </validator>
</action>

# Then implement the logic

package MyApp::Validator::Date;

use strict;
use base qw( Workflow::Validator );
use DateTime::Format::Strptime;
use Workflow::Exception qw( configuration_error );

__PACKAGE__->mk_accessors( 'formatter' );

sub _init {
    my ( $self, $params ) = @_;
    unless ( $params->{date_format} ) {
        configuration_error
            "You must define a value for 'date_format' in ",
            "declaration of validator ", $self->name;
    }
    if ( ref $params->{date_format} ) {
        configuration_error
            "The value for 'date_format' must be a simple scalar in ",
            "declaration of validator ", $self->name;
    }
    my $formatter = DateTime::Format::Strptime->new(
                             pattern => $params->{date_format},
                             on_error => 'undef' );
    $self->formatter( $formatter );
}

sub validate {
    my ( $self, $wf, $date_string ) = @_;
    my $fmt = $self->formatter;
    my $date_object = $fmt->parse_datetime( $date_string );
    unless ( $date_object ) {
        validation_error
            "Date '$date_string' does not match pattern '", $fmt->pattern, "' ",
            "due to error '", $fmt->errstr, "'";
    }
}

DESCRIPTION

Validators specified by 'validator_name' are looked up in the Workflow::Factory which reads a separate configuration and generates validators. (Generally all validators should be declared, but it is not required.)

Validators are objects with a single public method, 'validate()' that take as arguments a workflow object and a list of parameters. The parameters are filled in by the workflow engine according to the instantiation declaration in the Action.

The idea behind a validator is that it validates data but does not care where it comes from.

SUBCLASSING

Strategy

Methods

_init( \%params )

Called when the validator is first initialized. If you do not have sufficient information in \%params you should throw an exception.

validate( $workflow, $data )

Determine whether your $data is true or false. If necessary you can get the application context information 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>