Provided by: libcgi-validop-perl_0.56-2_all bug

NAME

       CGI::ValidOp::Check - base class for CGI::ValidOp checks

SYNOPSIS

           package CGI::ValidOp::Check::demo;
           use base qw/ CGI::ValidOp::Check /;

           sub default {
               (
                   qr/^demo$/,                  # validator
                   '$label must equal "demo."', # error message
               )
           }

           sub color {
               my $self = shift;
               (
                   sub {
                       my( $value, $color ) = @_;
                       $self->pass( $1 ) if $value =~ /^($color)$/i;
                       $self->fail( "\$label must be the color: $color." );
                   },
               )
           }

DESCRIPTION

       CGI::ValidOp::Check contains all the code to validate data from CGI::ValidOp::Param
       objects, and enables simple creation your own checks.  Unless you're creating or testing
       your own checks, you should use and read the documentation for CGI::ValidOp instead.

   How checks are used
       Each check module must contain at least one check, and can contain as many as you care to
       create.  This document walks through the creation of one module containing mutliple
       checks.  Some of ValidOp's default checks are organized by types of data (e.g. 'text',
       'number'), but there's nothing to say you must also do this.  You may find it convenient
       to package all the checks for one project in a single module.

       Your check can be used in three ways.  The first is with a simple scalar corresponding to
       the module name:

           $validop->param( 'price', [ 'mychecks' ]);

       The second is by calling a particular check within the package:

           $validop->param( 'price', [ 'mychecks::robot' ]);

       The third is by passing parameters to either the module or a check:

           $validop->param( 'price', [ 'mychecks(3,6)' ]);
           $validop->param( 'price', [ 'mychecks::robot("Robbie")' ]);

METHODS

       Unless you're creating or testing your own checks, this reference is not likely to help
       you.  You can use ValidOp's public API without knowing a thing about ValidOp::Check's
       internals.

   params()
       The 'params' method returns a list passed to the check by the user:

           $validop->param( 'price', [ 'mychecks(3,6)' ]);

       These parameters are captured by splitting the contents of the parenthesis on commas.  The
       resulting list is made available with the 'params' method.

   validator( $regexp_or_coderef )
       Sets or returns the validator.

   errmsg( $error_message )
       Sets or returns the error message.  When CGI::ValidOp::Param parses these error messages,
       it replaces every isntance of $label with the parameter's 'label' property or, if that
       does not exist, with the parameter's 'name'.

   check( $tainted_value )
       check() runs its calling object's validator against the incoming tainted value.  It
       returns the resulting value on success, or "undef" on failure.  check() itself does very
       little work; it finds what type of validator it has (regex and coderef are the only types
       currently allowed) and farms out the work to the appropriate method.

   check_regexp( $tainted, $validator )
       check_regexp() captures the result of matching $tainted against $validator, using code
       similar to this:

           $tainted =~ /($validator)/;
           return $1;

       Note that the return value is untainted.  Also note that the code does not anchor the
       regular expression with ^ (at the beginning) or $ (at the end).  In other words, if you
       used this quoted regex as a check:

           qr/demo/

       any string containing "demo" (e.g. "demographics," "modemophobia") would pass.  This may
       or may not be what you intend.

   check_code( $tainted, $validator )
       check_code() passes $tainted to the anonymous subroutine referenced by $validator and
       returns the result.  The two most notable differences from regex checks are that the value
       of params() is passed into the validator subroutine and that the entire thing croaks if
       the return value is tainted.

       ValidOp's default behavior is to die like a dog if your coderef returns a tainted value.
       This safe default can be changed by returning a third list item from your check
       subroutine, a hashref of additional properties:

           sub should_allow_tainted {(
               sub { $_[ 0 ] },
               'This should be an error message',
               { allow_tainted => 1, }
           )}

   is_tainted

CREATING A CHECK MODULE

   Starting a check module
       For the moment, your check module must be in the CGI::ValidOp::Check namespace; future
       versions will allow more flexibility.  The module must be in Perl's search path.

           package CGI::ValidOp::Check::demo;

       You must subclass CGI::ValidOp::Check for your module.  It contains methods that the rest
       of the code uses to perform the validation.

           use base qw/ CGI::ValidOp::Check /;

   Creating checks
       Each check is completely defined by a single subroutine.  If you define only one check in
       your module, it should be called 'default'.  Using only the module name as a check, the
       'default' subroutine is called.  There's nothing to stop you calling your single check
       something else, but it does mean less intuitive use.

       Checks return one to three scalar values.  The first value is the check itself, and is
       required.  The second value is an optional error message.  The third is an optional list
       of additional properties, defined for the check and made available as methods.

           sub check_name {
               ( $check, $errmsg, \%options )
           }

   Types of checks
       Quoted regular expression

       The simplest checks are quoted regular expressions.  These are perfect for relatively
       static data.  This one checks that the incoming value is "demo" and sets a custom error
       message.  Any instance of '$label' in an error message is substituted with the parameter's
       'label' property, if you define one, or the parameter's 'name' property (which is required
       and thus guaranteed to exist).

           sub default {
               (
                   qr/^demo$/,                  # validator
                   '$label must equal "demo."', # error message
               )
           }

       Parameters are validated against Regex checks with the check_regexp method.

       You cannot pass parameters to a regex check (more to the point you can, but they'll be
       ignored).

       Subroutine reference

       These checks can be much more powerful and flexible, but require a little extra work.

           sub color {
               my $self = shift;
               (
                   sub {
                       my( $value, $color ) = @_;
                       return $1 if $value =~ /^($color)$/i;
                       $self->errmsg( "\$label must be the color: $color." );
                       return;
                   },
               )
           }

       You'll note that the check only returns one item, an anonymous subroutine.  This coderef
       sets the check's error message with the 'errmsg' method, allowing it to pass incoming
       parameters into the error message.  (You could supply an error message here as the second
       array element, but it would be overridden.)

       Parameters are validated against coderef checks with the check_code method:

       Right now the only additional property available ValidOp checks is 'allow_tainted.'
       ValidOp's stock 'length' check uses this, reasoning that just knowing the length of an
       incoming value isn't reason enough to trust it.

           package Main;

           my $demo = CGI::ValidOp::Check::demo->new;
           is( $demo->check( 'failure' ), undef );
           is( $demo->check( 'demo' ), 'demo' );
               my $value = $demo->check( 'demo' );
           ok( ! $demo->is_tainted( $value ));

           my $demo_color = CGI::ValidOp::Check::demo->new( 'color', 'red' );
           is( $demo_color->check( 'green' ), undef );
           is( $demo_color->errmsg, '$label must be the color: red.' );
           is( $demo_color->check( 'red' ), 'red' );

AUTHOR

       Randall Hansen <legless@cpan.org>

COPYRIGHT

       Copyright (c) 2003-2005 Randall Hansen. All rights reserved.

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

       See http://www.perl.com/perl/misc/Artistic.html