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package Valiant::Validator;
use Moo::Role;
requires 'validate';
1;
HideShow 198 lines of Pod
=head1 NAME
Valiant::Validator - A role to define the validator interface.
=head1 SYNOPSIS
    package MySpecialValidator;
    use Moo;
    with 'Valiant::Validator';
    sub validate {
      my ($self, $object, $options) = @_;
      # DO your custom validation here.  Remember if you want to support
      # strict and message you should pass $options to any errors:
      # $object->errors->add('_base', 'Invalid', $options);
      # This method doesn't have to return anything in particular.
    }
=head1 DESCRIPTION
This is a base role for defining a validator.  This should be a class that
defines a C<validate> method. Here's a more detailed example that shows
using a custom validator with a validatable object:
    package Local::Test::Validator::Box;
    use Moo;
    with 'Valiant::Validator';
    has max_size => (is=>'ro', required=>1);
    sub validate {
      my ($self, $record, $opts) = @_;
      my $size = $record->height + $record->width + $record->length;
      if($size > $self->max_size) {
        $record->errors->add(_base=>"Total of all size cannot exceed ${\$self->max_size}", $opts),
      }
    }
    package Local::Test::Box;
    use Moo;
    use Valiant::Validations;
    has [qw(height width length)] => (is=>'ro', required=>1);
    validates [qw(height width length)] => (numericality=>+{});
    validates_with 'Box', max_size=>25;
    validates_with 'Box', max_size=>50, on=>'big', message=>'Big for Big!!';
    validates_with 'Box', max_size=>30, on=>'big', if=>'is_very_tall';
    sub is_very_tall {
      my ($self) = @_;
      return $self->height > 30 ? 1:0;
    }
When used with C<validates_with> we filter any extra arguments outside the globals
(C<on>, C<if/unless>, C<message>, C<strict>) and pass them as init args when creating
the validator.
A Validator is created once when the class uses it and exists for the full life cycle
of the validatable object.
Generally you would write a validator class like this when the validation is very complex
and cannot be tied to a specific attribute.  If it can be tied to an attribute then you
might prefer to use   L<Valiant::Validator::Each>.
=head1 PREPACKAGED VALIDATOR CLASSES
The following attribute validator classes are shipped with L<Valiant>.  Please see the package POD for
usage details (this is only a sparse summary)
=head2 Absence
Checks that a value is absent (undefinef or empty).
See L<Valiant::Validator::Absence> for details.
=head2 Array
Validations on an array value.  Has options for nested errors when the array contains objects that
themselves are validatible.
See L<Valiant::Validator::Array> for details.
=head2 Boolean
Returns errors messages based on the boolean state of an attribute.
See L<Valiant::Validator::Boolean> for details.
=head2 Check
Use your existing L<Type::Tiny> constraints with L<Valiant>
See L<Valiant::Validator::Check> for details.
=head2 Confirmation
Add a confirmation error check.  Used for when you want to verify that a given field is correct
(such as when a user submits a new password or an email address).
See L<Valiant::Validator::Confirmation> for details.
=head2 Date
Value must conform to standard date format (default is YYYY-MM-DD or eg 2000-01-01) and be a valid date.
See L<Valiant::Validator::Date> for details.
=head2 Exclusion
Value cannot match a fixed list.
See L<Valiant::Validator::Exclusion> for details.
=head2 Format
Value must be a string tht matched a given format or regular expression.
See L<Valiant::Validator::Format> for details.
=head2 Inclusion
Value must be one of a fixed list
See L<Valiant::Validator::Inclusion> for details.
=head2 Length
Value must be a string with given minimum and maximum lengths.
See L<Valiant::Validator::Length> for details.
=head2 Numericality
Validate various types of numbers.
See L<Valiant::Validator::Numericality> for details.
=head2 Object
Value is an object.  Allows one to have nested validations when the object itself can be validated.
See L<Valiant::Validator::Object> for details.
=head2 OnlyOf
Validates that only one or more of a group of attributes is defined.  
See L<Valiant::Validator::OnlyOf> for details.
=head2 Presence
That the value is defined and not empty
See L<Valiant::Validator::Absence> for details.
=head2 Unique
That the value is unique based on some custom logic that your class must provide.
See L<Valiant::Validator::Unique> for details.
=head2 With
Use a subroutine reference or the name of a method on your class to provide validation.
See L<Valiant::Validator::With> for details.
=head2 Scalar
Verifies that the value is a string or number, basically a Perl scalar.
See L<Valiant::Validator::Scalar> for details.
=head2 Special Validators
The following validators are not considered for end users but have documentation you might
find useful in furthering your knowledge of L<Valiant>:  L<Valiant::Validator::Collection>,
L<Valiant::Validator::Each>.
=head1 SEE ALSO
  
L<Valiant>, L<Valiant::Validator::Each>.
=head1 AUTHOR
  
See L<Valiant>
=head1 COPYRIGHT & LICENSE
  
See L<Valiant>
=cut