NAME Validation::Class - Centralized Data Validation Framework VERSION version 3.3.3 SYNOPSIS use MyApp::Validation; my $input = MyApp::Validation->new(params => $params); unless ($input->validate()){ return $input->errors_to_string; } DESCRIPTION Validation::Class is a different approach to data validation, it attempts to simplify and centralize data validation rules to ensure DRY (don't repeat yourself) code. The primary intent of this module is to provide a simplistic validation framework. Your validation class is your data input firewall and can be used anywhere and is flexible enough in an MVC environment to be used in both the Controller and Model. A validation class is defined as follows: package MyApp::Validation; use Validation::Class; # a validation rule fld 'login' => { label => 'User Login', error => 'Login invalid.', required => 1, validation => sub { my ($self, $this_field, $all_params) = @_; return $this_field->{value} eq 'admin' ? 1 : 0; } }; # a validation rule fld 'password' => { label => 'User Password', error => 'Password invalid.', required => 1, validation => sub { my ($self, $this_field, $all_params) = @_; return $this_field->{value} eq 'pass' ? 1 : 0; } }; 1; The fields defined will be used to validate the specified input parameters. You specify the input parameters at instantiation, parameters should take the form of a hashref of key/value pairs. Multi-level (nested) hashrefs are allowed and are inflated/deflated in accordance with the rules of Hash::Flatten or your hash inflator configuration. The following is an example on using your validate class to validate input in various scenarios: # web app package MyApp; use MyApp::Validation; use Misc::WebAppFramework; get '/auth' => sub { # get user input parameters my $params = shift; # initialize validation class and set input parameters my $rules = MyApp::Validation->new(params => $params); unless ($rules->validate('login', 'password')) { # print errors to browser unless validation is successful return $rules->errors_to_string; } return 'you have authenticated'; }; BUILDING A VALIDATION CLASS package MyApp::Validation; use Validation::Class; # a validation rule template mixin 'basic' => { required => 1, min_length => 1, max_length => 255, filters => ['lowercase', 'alphanumeric'] }; # a validation rule field 'user.login' => { mixin => 'basic', label => 'user login', error => 'login invalid', validation => sub { my ($self, $this, $fields) = @_; return $this->{value} eq 'admin' ? 1 : 0; } }; # a validation rule field 'user.password' => { mixin => 'basic', label => 'user login', error => 'login invalid', validation => sub { my ($self, $this, $fields) = @_; return $this->{value} eq 'pass' ? 1 : 0; } }; 1; THE MIXIN KEYWORD The mixin keyword (or mxn) creates a validation rules template that can be applied to any field using the mixin directive. package MyApp::Validation; use Validation::Class; mixin 'constrain' => { required => 1, min_length => 1, max_length => 255, ... }; # e.g. field 'login' => { mixin => 'constrain', ... }; THE FILTER KEYWORD The filter keyword (or flt) creates custom filters to be used in your field definitions. package MyApp::Validation; use Validation::Class; filter 'usa_telephone_number_converter' => sub { $_[0] =~ s/\D//g; my ($ac, $pre, $num) = $_[0] =~ /(\d{3})(\d{3})(\d{4})/; $_[0] = "($ac) $pre-$num"; }; # e.g. field 'my_telephone' => { filter => ['trim', 'usa_telephone_number_converter'], ... }; THE DIRECTIVE KEYWORD The directive keyword (or dir) creates custom validator directives to be used in your field definitions. The routine is passed two parameters, the value of directive and the value of the field the validator is being processed against. The validator should return true or false. package MyApp::Validation; use Validation::Class; directive 'between' => sub { my ($directive, $value, $field, $class) = @_; my ($min, $max) = split /\-/, $directive; unless ($value > $min && $value < $max) { my $handle = $field->{label} || $field->{name}; $class->error($field, "$handle must be between $directive"); return 0; } return 1; }; # e.g. field 'hours' => { between => '00-24', ... }; THE FIELD KEYWORD The field keyword (or fld) creates a validation block and defines validation rules for reuse in code. The field keyword should correspond with the parameter name expected to be passed to your validation class. package MyApp::Validation; use Validation::Class; field 'login' => { required => 1, min_length => 1, max_length => 255, ... }; The field keyword takes two arguments, the field name and a hashref of key/values pairs. FILTERING INCOMING DATA Validation::Class supports pre/post filtering but is configured to pre-filter incoming data. This means that based upon the filtering options supplied within the individual fields, filtering will happen before validation (technically at instantiation and again just before validation). As expected, this is configurable via the filtering attribute. A WORD OF CAUTION: Validation::Class is configured to pre-filter incoming data which boosts application security and is best used with passive filtering (e.g. converting character case - filtering which only alters the input in predictable ways), versus aggressive filtering (e.g. formatting a telephone number) which completely and permanently changes the incoming data ... so much so that if the validation still fails ... errors that are reported may not match the data that was submitted. If you're sure you'd rather employ aggressive filtering, I suggest setting the filtering attribute to 'post' for post-filtering or setting it to '' non and applying the filters manually via apply_filters(). AUTO-SERIALIZATION/DESERIALIZATION Validation::Class supports hash automatic serialization/deserialization which means that you can set the parameters using a hashref of nested hashrefs and validate against them, or set the parameters using a hashref of key/value pairs and validate against that. This function is provided in Validation::Class via Hash::Flatten. The following is an example of that: my $params = { user => { login => 'admin', password => 'pass' } }; my $rules = MyApp::Validation->new(params => $params); # or my $params = { 'user.login' => 'admin', 'user.password' => 'pass' }; my $rules = MyApp::Validation->new(params => $params); # field definition using field('user.login', ...) # and field('user.password', ...) will match against the parameters above # after filtering, validation, etc ... return your params as a hashref if # needed my $params = $rules->get_params_hash; SEPARATION OF CONCERNS For larger applications where a single validation class might become cluttered and inefficient, Validation::Class comes equipped to help you separate your validation rules into separate classes. The idea is that you'll end up with a main validation class (most likely empty) that will simply serve as your point of entry into your relative (child) classes. The following is an example of this: package MyVal::User; use Validation::Class; field name => { ... }; field email => { ... }; field login => { ... }; field password => { ... }; package MyVal::Profile; use Validation::Class; field age => { ... }; field sex => { ... }; field birthday => { ... }; package MyVal; use Validation::Class; __PACKAGE__->load_classes; package main; my $rules = MyVal->new(params => $params); my $user = $rules->class('user'); my $profile = $rules->class('profile'); ... 1; DEFAULT FIELD/MIXIN DIRECTIVES package MyApp::Validation; use Validation::Class; # a validation template mixin '...' => { # mixin directives here ... }; # a validation rule field '...' => { # field directives here ... }; 1; When building a validation class, the first encountered and arguably two most important keyword functions are field() and mixin(), which are used to declare their respective properties. A mixin() declares a validation template where its properties are intended to be copied within field() declarations which declares validation rules, filters and other properties. Both the field() and mixin() declarations/functions require two parameters, the first being a name, used to identify the declaration and to be matched against incoming input parameters and the second being a hashref of key/value pairs. The key(s) within a declaration are commonly referred to as directives. The following is a list of default directives which can be used in field/mixin declarations: alias The alias directive is useful when many different parameters with different names can be validated using a single rule. E.g. The paging parameters in a webapp may take on different names but require the same validation. # the alias directive field 'pager' => { alias => ['page_user_list', 'page_other_list'] ... }; default The default directive is used as a default value for a field to be used when a matching parameter is not present. # the default directive field 'quantity' => { default => 1, ... }; error/errors The error/errors directive is used to replace the system generated error messages when a particular field doesn't validate. If a field fails multiple directives, multiple errors will be generated for the same field. This may not be desirable, the error directive overrides this behavior and only the specified error is registered and displayed. # the error(s) directive field 'foobar' => { errors => 'Foobar failed processing, Wtf?', ... }; filtering The filtering directive is used to control when field filters are applied. The default recognized values are pre/post. A value of 'pre' instructs the validation class to apply the field's filters at instantiation and before validation whereas a value of 'post' instructs the validation class to apply the field's filters after validation. Alternatively, a value of undef or '' will bypass filtering altogether. # the filtering directive field 'foobar' => { filtering => 'post', ... }; label The label directive is used as a user-friendly reference when the field name is a serialized hash key or just plain ugly. # the label directive field 'hashref.foo.bar' => { label => 'Foo Bar', ... }; mixin The mixin directive is used to create a template of directives to be applied to other fields. mixin 'ID' => { required => 1, min_length => 1, max_length => 11 }; # the mixin directive field 'user.id' => { mixin => 'ID', ... }; mixin_field The mixin directive is used to copy all directives from an existing field except for the name, label, and validation directives. # the mixin_field directive field 'foobar' => { label => 'Foo Bar', required => 1 }; field 'barbaz' => { mixin_field => 'foobar', label => 'Bar Baz', ... }; name The name directive is used *internally* and cannot be changed. # the name directive field 'thename' => { ... }; required The required directive is an important directive but can be misunderstood. The required directive is used to ensure the submitted parameter exists and has a value. If the parameter is never submitted, the directive is effectively skipped. This directive can be thought of as the "must-have-a-value-if-exists" directive. # the required directive field 'foobar' => { required => 1, ... }; # fail my $rules = MyApp::Validation->new(params => { }); $rules->validate('foobar'); # fail my $rules = MyApp::Validation->new(params => { foobar => '' }); $rules->validate('foobar'); # pass my $rules = MyApp::Validation->new(params => { foobar => 'Nice' }); $rules->validate('foobar'); See the toggle functionality within the validate() method. This method allows you to temporarily alter whether a field is required or not. validation The validation directive is a coderef used add additional custom validation to the field. The coderef must return true (to pass) or false (to fail). Custom error messages can be set from within the coderef so make sure they are set based on appropriate logic as the registration of error message are not contingent on the success or failure of the routine. # the validation directive field 'login' => { validation => sub { my ($self, $this_field, $all_params) = @_; return 0 unless $this_field->{value}; return $this_field->{value} eq 'admin' ? 1 : 0; }, ... }; value The value directive is used internally to store the field's matching parameter's value. This value can be set in the definition but SHOULD NOT be used as a default value unless you're sure no parameter will overwrite it during run-time. If you need to set a default value, see the default directive. # the value directive field 'quantity' => { value => 1, ... }; DEFAULT FIELD/MIXIN FILTER DIRECTIVES filters The filters directive is used to correct, alter and/or format the values of the matching input parameter. Note: Filtering is applied before validation. The filter directive can have multiple filters (even a coderef) in the form of an arrayref of values. # the filter(s) directive field 'text' => { filters => [qw/trim strip/ => sub { $_[0] =~ s/\D//g; }], ... }; The following is a list of default filters that may be used with the filter directive: alpha The alpha filter removes all non-Alphabetic characters from the field's value. field 'foobar' => { filter => 'alpha', }; alphanumeric The alpha filter removes all non-Alphabetic and non-Numeric characters from the field's value. field 'foobar' => { filter => 'alphanumeric', }; capitalize The capitalize filter attempts to capitalize the first word in each sentence, where sentences are separated by a period and space, within the field's value. field 'foobar' => { filter => 'capitalize', }; decimal The decimal filter removes all non-decimal-based characters from the field's value. Allows only: decimal, comma, and numbers. field 'foobar' => { filter => 'decimal', }; numeric The numeric filter removes all non-numeric characters from the field's value. field 'foobar' => { filter => 'numeric', }; strip As with the trim filter the strip filter removes leading and trailing whitespaces from the field's value and additionally removes multiple whitespaces from between the values characters. field 'foobar' => { filter => 'strip', }; titlecase The titlecase filter converts the field's value to titlecase by capitalizing the first letter of each word. field 'foobar' => { filter => 'titlecase', }; trim The trim filter removes leading and trailing whitespace from the field's value. field 'foobar' => { filter => 'trim', }; uppercase The uppercase filter converts the field's value to uppercase. field 'foobar' => { filter => 'uppercase', }; DEFAULT FIELD/MIXIN VALIDATOR DIRECTIVES package MyApp::Validation; use Validation::Class; # a validation rule with validator directives field 'telephone_number' => { length => 14, pattern => '(###) ###-####', ... }; 1; Validator directives are special directives with associated validation code that is used to validate common use cases such as "checking the length of a parameter", etc. The following is a list of the default validators which can be used in field/mixin declarations: between # the between directive field 'foobar' => { between => '1-5', ... }; depends_on # the depends_on directive field 'change_password' => { depends_on => ['password', 'password_confirm'], ... }; length # the length directive field 'foobar' => { length => 20, ... }; matches # the matches directive field 'this_field' => { matches => 'another_field', ... }; max_alpha # the max_alpha directive field 'password' => { max_alpha => 30, ... }; max_digits # the max_digits directive field 'password' => { max_digits => 5, ... }; max_length # the max_length directive field 'foobar' => { max_length => '...', ... }; max_sum # the max_sum directive field 'vacation_days' => { max_sum => 5, ... }; max_symbols # the max_symbols directive field 'password' => { max_symbols => 1, ... }; min_alpha # the min_alpha directive field 'password' => { min_alpha => 2, ... }; min_digits # the min_digits directive field 'password' => { min_digits => 1, ... }; min_length # the min_length directive field 'foobar' => { min_length => '...', ... }; min_sum # the min_sum directive field 'vacation_days' => { min_sum => 0, ... }; min_symbols # the min_symbols directive field 'password' => { min_symbols => 0, ... }; options # the options directive field 'status' => { options => 'Active, Inactive', ... }; pattern # the pattern directive field 'telephone' => { # simple pattern pattern => '### ###-####', ... }; field 'country_code' => { # simple pattern pattern => 'XX', filter => 'uppercase' ... }; field 'complex' => { # regex pattern pattern => qr/[0-9]+\,\s\.\.\./, ... }; THE VALIDATION CLASS The following is an example of how to use your constructed validation class in other code, .e.g. Web App Controller, etc. use MyApp::Validation; my $input = MyApp::Validation->new(params => $params); unless ($input->validate('field1','field2')){ return $input->errors_to_string; } Feeling lazy? Have your validation class automatically find the appropriate fields to validate against (params must match field names). use MyApp::Validation; my $input = MyApp::Validation->new(params => $params); unless ($input->validate){ return $input->errors_to_string; } You can define an alias to automatically map a parameter to a validation field whereby a field definition will have an alias attribute containing an arrayref of alternate parameters that can be matched against passed-in parameters. package MyApp::Validation; field 'foo.bar' => { ..., alias => [ 'foo', 'bar', 'baz', 'bax' ] }; use MyApp::Validation; my $input = MyApp::Validation->new(params => { foo => 1 }); unless ($input->validate(){ return $input->errors_to_string; } new The new method instantiates and returns an instance of your validation class. use MyApp::Validation; my $input = MyApp::Validation->new; $input->params($params); ... my $input = MyApp::Validation->new(params => $params); ... VALIDATION CLASS ATTRIBUTES ignore_unknown The ignore_unknown boolean determines whether your application will live or die upon encountering unregistered field directives during validation. my $self = MyApp::Validation->new(params => $params, ignore_unknown => 1); $self->ignore_unknown(1); ... fields The fields attribute returns a hashref of defined fields, filtered and merged with their parameter counterparts. my $self = MyApp::Validation->new(fields => $fields); my $fields = $self->fields(); ... filtering The filtering attribute (by default set to 'pre') controls when incoming data is filtered. Setting this attribute to 'post' will defer filtering until after validation which allows any errors messages to report errors based on the unaltered data. Alternatively, setting the filtering attribute to '' or undef will bypass all filtering unless explicitly defined at the field-level. my $self = MyApp::Validation->new(filtering => 'post'); $self->validate(); ... filters The filters attribute returns a hashref of pre-defined filter definitions. my $filters = $self->filters(); ... hash_inflator The hash_inflator value determines how the hash serializer (inflation/deflation) behaves. The value must be a hashref of "OPTIONS" in Hash::Flatten options. Purely for the sake of consistency, you can use lowercase keys (with underscores) which will be converted to camel-cased keys before passed to the serializer. my $self = MyApp::Validation->new( hash_inflator => { hash_delimiter => '/', array_delimiter => '//' } ); ... mixins The mixins attribute returns a hashref of defined validation templates. my $mixins = $self->mixins(); ... params The params attribute gets/sets the parameters to be validated. my $input = { ... }; my $self = MyApp::Validation->new(params => $input); $self->params($input); my $params = $self->params(); ... report_unknown The report_unknown boolean determines whether your application will report unregistered fields as class-level errors upon encountering unregistered field directives during validation. my $self = MyApp::Validation->new(params => $params, ignore_unknown => 1, report_unknown => 1); $self->report_unknown(1); ... stashed The stashed attribute represents a list of field names stored to be used in validation later. If the stashed attribute contains a list you can omit arguments to the validate method. $self->stashed([qw/this that .../]); VALIDATION CLASS METHODS apply_filters The apply_filters method (usually called automatically based on the filtering attribute) can be used to run the currently defined parameters through the filters defined in the fields. my $rules = MyVal->new(filtering => '', params => $params); if ($rules->validate) { $rules->apply_filters; } else { print $rules->errors_to_string; # print errors on unaltered parameters } class The class method returns a new initialize child validation class under the namespace of the calling class that issued the load_classes() method call. Existing parameters and configuration options are passed to the child class's constructor. All attributes can be easily overwritten using the attribute's accessors on the child class. package MyVal; use Validation::Class; __PACKAGE__->load_classes; package main; my $rules = MyVal->new(params => $params); my $kid1 = $rules->class('Child'); # loads MyVal::Child; my $kid2 = $rules->class('StepChild'); # loads MyVal::StepChild; my $kid3 = $rules->class('child'); # loads MyVal::Child; my $kid4 = $rules->class('step_child'); # loads MyVal::StepChild; 1; clear_queue The clear_queue method resets the queue container, see the queue method for more information on queuing fields to be validated. The clear_queue method has yet another useful behavior in that it can assign the values of the queued parameters to the list it is passed, where the values are assigned in the same order queued. my $rules = MyVal->new(params => $params); $rules->queue(qw(name +email +login +password)); unless ($rules->validate) { return $rules->errors_to_string; } $rules->clear_queue(my($name, $email)); 1; clone The clone method is used to create new fields (rules) from existing fields on-the-fly. This is useful when you have a variable number of parameters being validated that can share existing validation rules. E.g., a web-form on a user's profile page may have dynamically created input boxes for the person's phone numbers allowing the user to add additional parameters to the web-form as needed, in that case as opposed to having multiple validation rules hardcoded for each parameter, you could hardcode one single rule and clone the rule at run-time. package MyVal; use Validation::Class; field phone => { required => 1 }; package main; my $rules = MyVal->new(params => $params); # clone phone rule at run-time to validate dynamically created parameters $rules->clone('phone', 'phone2', { label => 'Other Phone', required => 0 }); $rules->clone('phone', 'phone3', { label => 'Third Phone', required => 0 }); $rules->clone('phone', 'phone4', { label => 'Forth Phone', required => 0 }); $rules->validate(qw/phone phone2 phone3 phone4/); 1; error The error function is used to set and/or retrieve errors encountered during validation. The error function with no parameters returns the error message object which is an arrayref of error messages stored at class-level. # return all errors encountered/set as an arrayref return $self->error(); # return all errors specific to the specified field (at the field-level) # as an arrayref return $self->error('some_param'); # set an error specific to the specified field (at the field-level) # using the field object (hashref not field name) $self->error($field_object, "i am your error message"); unless ($self->validate) { my $fields = $self->error(); } error_count The error_count function returns the total number of error encountered from the last validation call. return $self->error_count(); unless ($self->validate) { print "Found ". $self->error_count ." Errors"; } error_fields The error_fields method returns a hashref of fields whose value is an arrayref of error messages. unless ($self->validate) { my $bad_fields = $self->error_fields(); } errors_to_string The errors_to_string function stringifies the error arrayref object using the specified delimiter or ', ' by default. return $self->errors_to_string(); return $self->errors_to_string("<br/>\n"); unless ($self->validate) { return $self->errors_to_string; } get_params The get_params method returns the values (in list form) of the parameters specified. if ($self->validate) { my $name_a = $self->get_params('name'); my ($name_b, $email, $login, $password) = $self->get_params(qw/name email login password/); # you should note that if the params dont exist they will return undef # ... meaning you should check that it exists before checking its value # e.g. if (defined $name) { if ($name eq '') { print 'name parameter was passed but was empty'; } } else { print 'name parameter was never submitted'; } } get_params_hash If your fields and parameters are designed with complex hash structures, the get_params_hash method returns the deserialized hashref of specified parameters based on the the default or custom configuration of the hash serializer Hash::Flatten. my $params = { 'user.login' => 'member', 'user.password' => 'abc123456' }; if ($self->validate(keys %$params)) { my $params = $self->get_params_hash; print $params->{user}->{login}; } load_classes The load_classes method is used Module::Find to load child classes for convenient access through the class() method. Existing parameters and configuration options are passed to the child class's constructor. All attributes can be easily overwritten using the attribute's accessors on the child class. package MyVal; use Validation::Class; __PACKAGE__->load_classes; 1; load_plugins The load_plugins method is used to load plugins that support Validation::Class. A Validation::Class plugin is little more than a Role (Moose::Role) that extends the Validation::Class core. As usual, an official Validation::Class plugin can be referred to using shorthand while custom plugins are called by prefixing a plus symbol to the fully-qualified plugin name. Learn more about plugins at Validation::Class::Plugins. package MyVal; use Validation::Class; __PACKAGE__->load_plugins('SuperX'); # loads Validation::Class::Plugin::SuperX __PACKAGE__->load_plugins('+MyApp::Validation::Plugin::SuperY'); 1; param The param method returns a single parameter by name. if ($self->param('chng_pass')) { $self->validate('password_confirmation'); } queue The queue method is a convenience method used specifically to append the stashed attribute allowing you to *queue* field to be validated. This method also allows you to set fields that must always be validated. # conditional validation flow WITHOUT the queue method # imagine a user profile update action my $rules = MyApp::Validation->new(params => $params); my @fields = qw/name login/; push @fields, 'email_confirm' if $rules->param('chg_email'); push @fields, 'password_confirm' if $rules->param('chg_pass'); ... if $rules->validate(@fields); # conditional validation WITH the queue method my $rules = MyApp::Validation->new(params => $params); $rules->queue(qw/name login/); $rules->queue(qw/email_confirm/) if $rules->param('chg_email'); $rules->queue(qw/password_confirm/) if $rules->param('chg_pass'); ... if $rules->validate(); # set fields that must ALWAYS be validated # imagine a simple REST server my $rules = MyApp::Validation->new(params => $params); $rules->queue(qw/login password/); if ($request eq '/resource/:id') { if ($rules->validate('id')) { # validated login, password and id ... } } reset The reset method clears all errors, fields and stashed field names, both at the class and individual field levels. $self->reset(); reset_errors The reset_errors method clears all errors, both at the class and individual field levels. This method is called automatically every time the validate() method is triggered. $self->reset_errors(); reset_fields The reset_fields method clears all errors and field values, both at the class and individual field levels. This method is executed automatically at instantiation. $self->reset_fields(); sanitize The sanitize method executes a set of routines that reset the parameter environment filtering any parameters present. This method is executed automatically at instantiation and validation. $self->sanitize(); set_params_hash Depending on how parameters are being input into your application, if your input parameters are already complex hash structures, The set_params_hash method will set and return the serialized version of your hashref based on the the default or custom configuration of the hash serializer Hash::Flatten. my $params = { user => { login => 'member', password => 'abc123456' } }; my $serialized_params = $self->set_params_hash($params); stash The stash method provides a container for context/instance specific information. The stash is particularly useful when custom validation routines require insight into context/instance specific operations. package MyApp::Validation; use Validation::Class; fld 'email' => { validation => sub { my $db = shift->stash->{database}; my $this = shift; return $db->find('email' => $this->{value}) ? 0 : 1 ; # email exists } }; package main; $self->stash( { database => $dbix_object } ); $self->stash( ftp => $net_ftp, database => $dbix_object ); ... validate The validate method returns true/false depending on whether all specified fields passed validation checks. use MyApp::Validation; my $input = MyApp::Validation->new(params => $params); # validate specific fields unless ($input->validate('field1','field2')){ return $input->errors_to_string; } # validate fields based on a regex pattern unless ($input->validate(qr/^field(\d+)?/)){ return $input->errors_to_string; } # validate existing parameters, if no parameters exist, # validate all fields ... which will return true unless field(s) exist # with a required directive unless ($input->validate()){ return $input->errors_to_string; } # validate all fields period, obviously unless ($input->validate(keys %{$input->fields})){ return $input->errors_to_string; } # validate specific parameters (by name) after mapping them to other fields my $parameter_map = { user => 'hey_im_not_named_login', pass => 'password_is_that_really_you' }; unless ($input->validate($parameter_map)){ return $input->errors_to_string; } Another cool trick the validate() method can perform is the ability to temporarily alter whether a field is required or not during run-time. This functionality is often referred to as the *toggle* function. This function is important when you define a field (or two or three) as required or non and want to change that per validation. This is done by calling the validate() method with a list of fields to be validated and prefixing the target fields with a plus or minus as follows: use MyApp::Validation; my $input = MyApp::Validation->new(params => $params); # validate specific fields, force name, email and phone to be required # regardless of the field definitions directives ... and force the age, sex # and birthday to be optional my @spec = qw(+name +email +phone -age -sex -birthday); unless ($input->validate(@spec)){ return $input->errors_to_string; } AUTHOR Al Newkirk <awncorp@cpan.org> COPYRIGHT AND LICENSE This software is copyright (c) 2011 by awncorp. This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.