Moosified Centralized Input Validation For Any Application
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NAME

Validation::Class - Centralized Input Validation for Any Application

VERSION

version 2.4.3

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
field '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
field '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 instantiaton, 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';
};

CHANGE NOTICE

Important Note! Validation::Class is subject to change, though not dramatically, you've been warned. Users of this library pre-v2 should not that the error accessors were changed. Validation::Class has been re-written using Moose. Sorry if you feel this bloats your application but using Moose was the better approach.

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 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 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 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 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 keword takes two arguments, the field name and a hashref of key/values pairs.

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;

SEPERATION OF CONCERNS

For larger applications were a single validation class might become cluttered and inefficient Validation::Class come equipped to help you seperate your validation rules into seperate 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 generate 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?',
    ...
};

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 used to ensure the submitted parameter exists and has a value. If the parameter is never submitted, the required directive has no effect and in-fact all filtering, validation, etc is then skipped.

# the required directive
field 'foobar'  => {
    required => 1,
    ...
};


# fail
my $rules = MyApp::Validation->new(params => {  });
$rules->validate('foobar');


# pass
my $rules = MyApp::Validation->new(params => {  foobar => 'Nii=cce });
$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 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 runtime. If you need to set a default value, see the default directive.

# the value directive
field 'quantity'  => {
    value => 1,
    ...
};

DEFAULT FIELD/MIXIN FILTER DIRECTIVES

filter/filters

The filter/filters directive is used to correct, altering 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'  => {
    filter => [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 seperated 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 whitespaces 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'  => {
    pattern => '### ###-####',
    ...
};


field 'country_code'  => {
    pattern => 'XX',
    filter  => 'uppercase'
    ...
};

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 thier parameter counterparts.

my $self = MyApp::Validation->new(fields => $fields);
my $fields = $self->fields();
...

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 LHash::Flatten/OPTIONS options. Purely for the sake of consistency, you can use lowercase keys (with underscores) which will be converted to camelcased 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);
...

reset_fields

The reset_fields attribute effectively resets any altered field objects at the class level. This method is called automatically everytime the new() method is triggered.

$self->reset_fields();

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

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('step_child'); # loads MyVal::StepChild;


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
        ...
    }
}

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);

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 everytime 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 called automatically everytime the validate() method is triggered.

$self->reset_fields();

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 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 runtime. 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.