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Powerful Data Validation Framework

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README.mkdn

NAME

Validation::Class - Powerful Data Validation Framework

VERSION

version 7.900020

SYNOPSIS

use Validation::Class::Simple::Streamer;

my $input = Validation::Class::Simple::Streamer->new($parameters);

# data validation rules for the username parameter
$input->check('username')->required->between('5-255');
$input->filters([qw/trim strip/]);

# data validation rule for the password parameter
$input->check('password')->required->between('5-255')->min_symbols(1);
$input->filters([qw/trim strip/]);

# perform validation
unless ($input) {
    # handle the failures
}

DESCRIPTION

Validation::Class is a scalable data validation library with interfaces for applications of all sizes. Validation::Class::Simple::Streamer is a great way to leverage this library for ad-hoc use-cases, Validation::Class::Simple is very well suited for applications of moderate sophistication where it makes sense to pre-declared validation rules, and Validation::Class is designed to transform class namespaces into data validation domains where consistency and reuse are primary concerns.

Validation::Class provides an extensible framework for defining reusable data validation rules. It ships with a complete set of pre-defined validations and filters referred to as "directives". The core feature-set consist of self-validating methods, validation profiles, reusable validation rules and templates, pre and post input filtering, class inheritance, automatic array handling, and extensibility (e.g. overriding default error messages, creating custom validators, creating custom input filters and much more). Validation::Class promotes DRY (don't repeat yourself) code. The main benefit in using Validation::Class is that the architecture is designed to increase the consistency of data input handling. The following is a more traditional usage of Validation::Class:

package MyApp::Person;

use Validation::Class;

# data validation template
mixin basic     => {
    required    => 1,
    max_length  => 255,
    filters     => [qw/trim strip/]
};

# data validation rules for the username parameter
field username  => {
    mixin       => 'basic',
    min_length  => 5
};

# data validation rules for the password parameter
field password  => {
    mixin       => 'basic',
    min_length  => 5,
    min_symbols => 1
};

# elsewhere in your application
my $person = MyApp::Person->new(username => 'admin', password => 'secr3t');

# validate rules on the person object
unless ($person->validates) {
    # handle the failures
}

1;

QUICKSTART

If you are looking for a simple in-line data validation module built using the same tenets and principles as Validation::Class, please review Validation::Class::Simple.

RATIONALE

If you are new to Validation::Class, or would like more information on the underpinnings of this library and how it views and approaches data validation, please review Validation::Class::Whitepaper.

KEYWORDS

attribute

The attribute keyword (or has) registers a class attribute. This is only a minimalistic variant of what you may have encountered in other object systems.

package MyApp::Person;

use Validate::Class;

attribute 'first_name' => 'Peter';
attribute 'last_name'  => 'Venkman';
attribute 'full_name'  => sub {

    my ($self) = @_;

    return join ', ', $self->last_name, $self->first_name;

};

1;

The attribute keyword takes two arguments, the attribute name and a constant or coderef that will be used as its default value.

build

The build keyword (or bld) registers a coderef to be run at instantiation much in the same way the common BUILD routine is used in modern OO frameworks.

package MyApp::Person;

use Validation::Class;

build sub {

    my ($self, $args) = @_;

    # run after instantiation in the order declared

};

The build keyword takes one argument, a coderef which is passed the instantiated class object.

directive

The directive keyword (or dir) registers custom validator directives to be used in your field definitions. This is a means of extending the list of directives per instance. See the list of core directives, Validation::Class::Directives, or review Validation::Class::Directive for insight into creating your own CPAN installable directives.

package MyApp::Directives;

use Validation::Class 'directive';

use Data::Validate::Email;

directive 'isa_email_address' => sub {

    my ($self, $proto, $field, $param) = @_;

    my $validator = Data::Validate::Email->new;

    unless ($validator->is_email($param)) {

        my $handle = $field->label || $field->name;

        $field->errors->add("$handle must be a valid email address");

        return 0;

    }

    return 1;

};

package MyApp::Person;

use Validate::Class;

use MyApp::Directives;

field 'email_address' => {
    isa_email_address => 1
};

1;

The directive keyword takes two arguments, the name of the directive and a coderef which will be used to validate the associated field. The coderef is passed four ordered parameters; a directive object, the class prototype object, the current field object, and the matching parameter's value. The validator (coderef) is evaluated by its return value as well as whether it altered any error containers.

field

The field keyword (or fld) registers a data validation rule for reuse and validation in code. The field name should correspond with the parameter name expected to be passed to your validation class or validated against.

package MyApp::Person;

use Validation::Class;

field 'username' => {
    required   => 1,
    min_length => 1,
    max_length => 255
};

The field keyword takes two arguments, the field name and a hashref of key/values pairs known as directives. For more information on pre-defined directives, please review the "list of core directives".

The field keyword also creates accessors which provide easy access to the field's corresponding parameter value(s). Accessors will be created using the field's name as a label having any special characters replaced with an underscore.

field 'send-reminders' => { # accessor will be created as send_reminders
    length   => 1
};

Protip: Field directives are used to validate scalar and array data. Don't use fields to store and validate objects. Please see the *has* keyword instead or use an object system with type constraints like Moose.

filter

The filter keyword (or flt) registers custom filters to be used in your field definitions. It is a means of extending the pre-existing filters declared by the "filters directive" before instantiation.

package MyApp::Directives;

use Validation::Class;

filter 'flatten' => sub {

    $_[0] =~ s/[\t\r\n]+/ /g;
    return $_[0];

};

package MyApp::Person;

use Validate::Class;

use MyApp::Directives;

field 'biography' => {
    filters => ['trim', 'flatten']
};

1;

The filter keyword takes two arguments, the name of the filter and a coderef which will be used to filter the value the associated field. The coderef is passed the value of the field and that value MUST be operated on directly. The coderef should also return the transformed value.

load

The load keyword (or set), which can also be used as a class method, provides options for extending the current class by declaring roles, plugins, etc.

The process of applying roles to the current class mainly involves copying the subject's methods and prototype configuration.

package MyApp::Person;

use Validation::Class;

load role => 'MyApp::User';

1;

The `roles` (or role) option is used to load and inherit functionality from other validation classes. These classes should be used and thought-of as roles although they can also be fully-functioning validation classes. This option accepts an arrayref or single argument.

package MyApp::Person;

use Validation::Class;

load roles => ['MyApp::User', 'MyApp::Visitor'];

1;

message

The message keyword (or msg) registers a class-level error message template that will be used in place of the error message defined in the corresponding directive class if defined. Error messages can also be overridden at the individual field-level as well. See the Validation::Class::Directive::Messages for instructions on how to override error messages at the field-level.

package MyApp::Person;

use Validation::Class;

field email_address => {
    required   => 1,
    min_length => 3,
    messages   => {
        # field-level error message override
        min_length => '%s is not even close to being a valid email address'
    }
};

# class-level error message overrides
message required   => '%s is needed to proceed';
message min_length => '%s needs more characters';

1;

The message keyword takes two arguments, the name of the directive whose error message you wish to override and a string which will be used to as a template which is feed to sprintf to format the message.

method

The method keyword (or mth) is used to register an auto-validating method. Similar to method signatures, an auto-validating method can leverage pre-existing validation rules and profiles to ensure a method has the required data necessary for execution.

package MyApp::Person;

use Validation::Class;

method 'register' => {

    input  => ['name', '+email', 'username', '+password', '+password2'],
    output => ['+id'], # optional output validation, dies on failure
    using  => sub {

        my ($self, @args) = @_;

        # do something registrationy

        $self->id(...); # set the ID field for output validation

        return $self;

    }

};

package main;

my $person = MyApp::Person->new(params => $params);

if ($person->register) {

    # handle the successful registration

}

1;

The method keyword takes two arguments, the name of the method to be created and a hashref of required key/value pairs. The hashref must have an `input` key whose value is either an arrayref of fields to be validated, or a scalar value which matches (a validation profile or auto-validating method name). The hashref must also have a `using` key whose value is a coderef which will be executed upon successfully validating the input. The `using` key/coderef can be omitted when a sub-routine of the same name prefixed with an underscore is present. Whether and what the method returns is yours to decide. The method will return 0 if validation fails.

Optionally the required hashref can have an `output` key whose value is either an arrayref of fields to be validated, or a scalar value which matches (a validation profile or auto-validating method name) which will be used to perform data validation after the aforementioned coderef has been executed.

Please note that output validation failure will cause the program to die, the premise behind this decision is based on the assumption that given successfully validated input a routine's output should be predictable and if an error occurs it is most-likely a program error as opposed to a user error.

See the ignore_failure and report_failure attributes on the prototype to control how method input validation failures are handled.

mixin

The mixin keyword (or mxn) registers a validation rule template that can be applied (or "mixed-in") to any field by specifying the mixin directive. Mixin directives are processed first so existing field directives will override any directives created by the mixin directive.

package MyApp::Person;

use Validation::Class;

mixin 'boilerplate' => {
    required   => 1,
    min_length => 1,
    max_length => 255
};

field 'username' => {
    # min_length, max_length, .. required will be overridden
    mixin    => 'boilerplate',
    required => 0
};

Since version 7.900015, all classes are automatically configured with the following default mixins for the sake of convenience:

mixin ':flg' => {
    required   => 1,
    min_length => 1,
    filters    => [qw/trim strip numeric/],
    between    => [0, 1]
};

mixin ':num' => {
    required   => 1,
    min_length => 1,
    filters    => [qw/trim strip numeric/]
};

mixin ':str' => {
    required   => 1,
    min_length => 1,
    filters    => [qw/trim strip/]
};

The mixin keyword takes two arguments, the mixin name and a hashref of key/values pairs known as directives.

profile

The profile keyword (or pro) registers a validation profile (coderef) which as in the traditional use of the term is a sequence of validation routines that validates data relevant to a specific action.

package MyApp::Person;

use Validation::Class;

profile 'check_email' => sub {

    my ($self, @args) = @_;

    if ($self->email_exists) {
        my $email = $self->fields->get('email');
        $email->errors->add('Email already exists');
        return 0;
    }

    return 1;

};

package main;

my $user = MyApp::Person->new(params => $params);

unless ($user->validate_profile('check_email')) {
    # handle failures
}

The profile keyword takes two arguments, a profile name and coderef which will be used to execute a sequence of actions for validation purposes.

METHODS

new

The new method instantiates a new class object, it performs a series of actions (magic) required for the class function properly, and for that reason, this method should never be overridden. Use the build keyword for hooking into the instantiation process.

In the event a foreign `new` method is detected, an `initialize_validator` method will be injected into the class containing the code (magic) necessary to normalize your environment.

package MyApp::Person;

use Validation::Class;

# hook
build sub {

    my ($self, @args) = @_; # on instantiation

};

sub new {

    # rolled my own
    my $self = bless {}, shift;

    # execute magic
    $self->initialize_validator;

}

prototype

The prototype method (or proto) returns an instance of the associated class prototype. The class prototype is responsible for manipulating and validating the data model (the class). It is not likely that you'll need to access this method directly, see Validation::Class::Prototype.

package MyApp::Person;

use Validation::Class;

package main;

my $person = MyApp::Person->new;

my $prototype = $person->prototype;

PROXY METHODS

Validation::Class mostly provides sugar functions for modeling your data validation requirements. Each class you create is associated with a *prototype* class which provides the data validation engine and keeps your class namespace free from pollution, please see Validation::Class::Prototype for more information on specific methods and attributes.

Validation::Class injects a few proxy methods into your class which are basically aliases to the corresponding prototype class methods, however it is possible to access the prototype directly using the proto/prototype methods.

class

$self->class;

See "class" in Validation::Class::Prototype for full documentation.

clear_queue

$self->clear_queue;

See "clear_queue" in Validation::Class::Prototype for full documentation.

error_count

$self->error_count;

See "error_count" in Validation::Class::Prototype for full documentation.

error_fields

$self->error_fields;

See "error_fields" in Validation::Class::Prototype for full documentation.

errors

$self->errors;

See "errors" in Validation::Class::Prototype for full documentation.

head2 errors_to_string

$self->errors_to_string;

See "errors_to_string" in Validation::Class::Prototype for full documentation.

get_errors

$self->get_errors;

See "get_errors" in Validation::Class::Prototype for full documentation.

get_fields

$self->get_fields;

See "get_fields" in Validation::Class::Prototype for full documentation.

get_hash

$self->get_hash;

See "get_hash" in Validation::Class::Prototype for full documentation.

get_params

$self->get_params;

See "get_params" in Validation::Class::Prototype for full documentation.

get_values

$self->get_values;

See "get_values" in Validation::Class::Prototype for full documentation.

fields

$self->fields;

See "fields" in Validation::Class::Prototype for full documentation.

filtering

$self->filtering;

See "filtering" in Validation::Class::Prototype for full documentation.

ignore_failure

$self->ignore_failure;

See "ignore_failure" in Validation::Class::Prototype for full documentation.

ignore_unknown

$self->ignore_unknown;

See "ignore_unknown" in Validation::Class::Prototype for full documentation.

param

$self->param;

See "param" in Validation::Class::Prototype for full documentation.

params

$self->params;

See "params" in Validation::Class::Prototype for full documentation.

queue

$self->queue;

See "queue" in Validation::Class::Prototype for full documentation.

report_failure

$self->report_failure;

See "report_failure" in Validation::Class::Prototype for full documentation.

report_unknown

$self->report_unknown;

See "report_unknown" in Validation::Class::Prototype for full documentation.

reset_errors

$self->reset_errors;

See "reset_errors" in Validation::Class::Prototype for full documentation.

reset_fields

$self->reset_fields;

See "reset_fields" in Validation::Class::Prototype for full documentation.

reset_params

$self->reset_params;

See "reset_params" in Validation::Class::Prototype for full documentation.

set_errors

$self->set_errors;

See "set_errors" in Validation::Class::Prototype for full documentation.

set_fields

$self->set_fields;

See "set_fields" in Validation::Class::Prototype for full documentation.

set_params

$self->set_params;

See "set_params" in Validation::Class::Prototype for full documentation.

set_method

$self->set_method;

See "set_method" in Validation::Class::Prototype for full documentation.

stash

$self->stash;

See "stash" in Validation::Class::Prototype for full documentation.

validate

$self->validate;

See "validate" in Validation::Class::Prototype for full documentation.

validate_method

$self->validate_method;

See "validate_method" in Validation::Class::Prototype for full documentation.

validate_profile

$self->validate_profile;

See "validate_profile" in Validation::Class::Prototype for full documentation.

EXTENSIBILITY

Validation::Class does NOT provide method modifiers but can be easily extended with Class::Method::Modifiers.

before

before foo => sub { ... };

See "before method(s) => sub { ... }" in Class::Method::Modifiers for full documentation.

around

around foo => sub { ... };

See "around method(s) => sub { ... }" in Class::Method::Modifiers for full documentation.

after

after foo => sub { ... };

See "after method(s) => sub { ... }" in Class::Method::Modifiers for full documentation.

SEE ALSO

If you have simple data validation needs, please review:

Validation::Class validates strings, not structures. If you need a means for validating object types you should be using a modern object system like Mo, Moo, Mouse, or Moose. Alternatively you could use Params::Validate.

In the event that you would like to look elsewhere for your data validation needs, the following is a list of other validation libraries/frameworks you might be interested in. If I've missed a really cool new validation library please let me know.

  • HTML::FormHandler

    This library seems to be the defacto standard for designing Moose classes with HTML-centric data validation rules.

  • Data::Verifier

    This library is a great approach towards adding robust validation logic to your existing Moose-based codebase.

  • Validate::Tiny

    This library is nice for simple use-cases, it has virtually no dependencies and solid test coverage.

AUTHOR

Al Newkirk anewkirk@ana.io

COPYRIGHT AND LICENSE

This software is copyright (c) 2011 by Al Newkirk.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

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