oracular (3) HTML::FormHandler::Manual::Validation.3pm.gz
NAME
HTML::FormHandler::Manual::Validation - validating fields
VERSION
version 0.40068
SYNOPSIS
Manual Index
There are many options for validating fields in FormHandler. Some validation is from field attributes,
some from form or field methods, some from 'apply' actions on the fields.
Field attributes for validation
Each individual field may have additional attributes that relate to validation, which are not documented
here. See the individual field documentation, linked from HTML::FormHandler::Manual::Fields.
required, required_when
Setting the 'required' flag on a field initiates a check for the existence of some value. If the field
does not have a value, the 'required' error message is issued.
has_field 'section' => ( required => 1,
messages => { required => 'Please provide a section' } );
Note that a required flag on a subfield -- a field inside a compound field or repeatable field -- does
not cause the containing field to be required. You need to set 'required' all the way up, if that's the
behavior that you want.
If a field is empty and *not* required, no other field validation will be performed unless the
'validate_when_empty' flag (see below) is set. The form's 'validate' method, however, will always be
called.
There is also the 'required_when' attribute, which works the same way as the 'when' key on the apply
actions.
has_field 'fee' => ( required_when => { 'fie' => 2 } );
When a 'required' or 'required_when' check fails, a 'missing' flag is set in the result:
if ( $field->missing ) { ... }
range_start, range_end
Starting and ending range for number fields.
unique
Attribute used by the DBIC model to check for uniqueness.
validate_when_empty
If its 'validate_when_empty' flag is set to a true value, then a field will always undergo validation
when its form is processed, even when that field is empty.
Validation methods
validate_method
You can provide a validation method for a field by setting a coderef with 'validate_method'.
has_field 'fox' => ( validate_method => \&check_fox );
sub check_fox {
my $self = shift; # self is the fox field
unless( $self->value eq .... ) {
$self->add_error('....');
}
}
validate_<field_name>
If you provide a 'validate_<field_name>' method it will be automatically used.
has_field 'cat';
sub validate_cat {
my ( $self, $field ) = @_; # self is the form
unless ( $field->value eq ... ) {
$field->add_error( '...' );
}
}
If the field name has periods in it, they should be replaced with underscores.
form validate method
A form validation method can be used to do cross-validation or validation checks that need information
from more than one field.
sub validate {
my $self = shift;
$self->field('foo')->add_error('....')
if( $self->field('foo')->value eq '..' &&
$self->field('bar')->value eq '..' );
}
field validate method
You can create a custom field to contain a commonly used validation. The validation in a custom field can
be done with 'apply' or by using a 'validate' method.
package MyApp::Form::Field::Custom;
use HTML::FormHandler::Moose;
extends 'HTML::FormHandler::Field'; # or a subclass of Field
sub validate {
....
}
Apply Actions: Filters, transformations, and constraints
The actions in the 'apply' array (stored in the 'actions' attribute) will be performed in the order they
are specified, allowing fine-grained control over inflation and validation. You can check constraints
after transformations and vice versa. You can weave all three types of actions in any order you need.
The two valid 'apply' array elements are 1) Moose types and 2) hashrefs with one of three keys: 'check',
'transform', and 'type'. The hashrefs will usually also have an additional key, 'message', with a string,
array or coderef providing an error message, which is localized.
The 'check' key can point to a regex, arrayref of strings, or coderef. The value of the 'transform' key
should be a coderef. The value of the 'type' key is a Moose type.
In addition to the check and type keys, you can provide a 'when' key to only perform this validation when
a particular field is a particular value:
has_field 'fee';
has_field 'fie' => ( apply => [
{ when => { fee => 1 }, check => qr/when/, message => 'Wrong fie' },
]);
has_field 'fo';
has_field 'fum_comp' => ( type => 'Compound' );
has_field 'fum_comp.one';
has_field 'fum_comp.two' => ( apply => [
{ when => { '+fee' => [1,2,3] }, check => qr/when/, message => 'Wrong two' },
]);
The field name key in the 'when' hashref is assumed to be a field at the same "level" as this field (i.e.
a sibling field in a compound). If you want to specify a field name from the form, prepend the name with
a '+'.
The 'when' hashref can contain multiple key/value pairs. This simply extends its test across multiple
fields; all fields named in the hashref's keys must match their respective values in order for the
overall 'when' test to pass.
when => { foo => 3 } # when the foo field value is 3
when => { foo => [1,2,3]} # when foo is 1, 2, or 3
when => { foo => sub { $_[0] > 0 }} # when foo is greater than 0
when => { foo => sub { $_[0] ne ''}} # when foo is the empty string
Transformations and coercions are called in an eval to catch the errors. Warnings are trapped in a
sigwarn handler.
If the conditions get too complicated to easily fit into a when condition, you can always create a
validation method instead.
See also HTML::FormHandler::Field and HTML::FormHandler::Validate. See
HTML::FormHandler::Manual::InflationDeflation for information on inflation and deflation.
Moose types
Moose types can be used to do both constraints and transformations. If a coercion exists it will be
applied, resulting in a transformation. After coercing, the result is checked. You can use type
constraints from MooseX::Types libraries or defined using Moose::Util::TypeConstraints.
FormHandler supplies a library of Moose types in HTML::FormHandler::Types.
use HTML::FormHandler::Types ('NotAllDigits');
has_field 'foo' => ( apply => [ NotAllDigits ] );
You can create your own library of types, too. Or you can create a type constraint in the form:
use Moose::Util::TypeConstraints;
subtype 'GreaterThan10'
=> as 'Int'
=> where { $_ > 10 }
=> message { "This number ($_) is not greater than 10" };
has_field 'text_gt' => ( apply=> [ 'GreaterThan10' ] );
Moose types can also be used for their coercions to do transformations.
subtype 'MyInt'
=> as 'Int';
coerce 'MyInt'
=> from 'MyStr'
=> via { return $1 if /(\d+)/ };
You can also use the 'type' keyword with a Moose type if you want to change the message:
has_field 'text_gt' => ( apply => [
{ type => 'GreaterThan10',
message => 'Number is too small' } ] );
transform
A 'transform' changes the format of a field's value, and does not need a message. It takes a coderef.
has_field 'another_field' => (
apply => [ { transform => sub{ sprintf '<%.1g>', $_[0] } } ]
);
Note that transformed values are not displayed in the HTML form unless the 'fif_from_value' flag is set.
The transformed values are saved to the database or returned in "$form->value".
'check' regex
Checks that field value matches the regex.
has_field 'some_field' => (
apply => [ { check => qr/aaa/, message => 'Must contain aaa' } ],
);
You can use regex libraries like Regexp::Common too:
use Regexp::Common ('URI');
...
has_field 'my_url' => ( apply => [
{ check => qr/$RE{URI}{HTTP}/,
message => 'Invalid URL' } ] );
'check' arrayref (matches)
Provide an arrayref of strings to match against.
has_field 'set_error' => (
apply => [
{ check => [ 'abc', 'bbb' ],
message => 'Must be "aaa" or "bbb"' }
]
);
'check' coderef
Provide a validation function to check. A 'check' coderef will be passed the current value of the field
and should return true or false. Note that the field is passed in as the second argument, to allow simple
functions to work properly.
has_field 'callback_pass' => (
apply => [
{ check => \&check_callback_pass,
message => 'Must contain number greater than 10', }
]
);
sub check_callback_pass {
my ( $value, $field ) = @_;
if( $value =~ /(\d+)/ ) {
return $1 > 10;
}
}
message
The message for the above checks can also be an arrayref or coderef. The arrayref is useful for
localized messages. You can also provide error messages for Moose types.
has_field 'message_sub' => (
apply => [
{ check => [ 'abc' ],
message => \&err_message }
]
);
sub err_message {
my ($value, $field ) = @_;
return $field->name . ': Must be "abc"';
}
has_field 'message_arrayref' => (
apply => [ { check => qr/aaa/,
message => ['Must contain [_1]', 'aaa'] } ],
);
has_field 'my_moose_type_field' => (
apply => [ { type => SomeType,
message => 'Invalid ...' } ] );
actions in a field class
To declare actions inside a field class use HTML::FormHandler::Moose and 'apply' sugar:
package MyApp::Field::Test;
use HTML::FormHandler::Moose;
extends 'HTML::FormHandler::Field;
apply [ 'SomeConstraint', { check => ..., message => .... } ];
1;
Actions specified with apply are cumulative. Actions may be specified in field classes and additional
actions added in the 'has_field' declaration.
You can see examples of field classes with 'apply' actions in the source for
HTML::FormHandler::Field::Money and HTML::FormHandler::Field::Email, and in t/constraints.t.
Dependency
The 'dependency' attribute is an array of arrays of field names. During validation, if any field in a
given group has a value that matches the pattern /\S/ (non-blank), the 'required' flag is set for all of
the fields in the group.
has '+dependency' => ( default => sub {
[
['address', 'city', 'state', 'zip'],
['cc_no', 'cc_expires'],
],
},
);
You can also use the 'required_when' flag to do something similar.
AUTHOR
FormHandler Contributors - see HTML::FormHandler
COPYRIGHT AND LICENSE
This software is copyright (c) 2017 by Gerda Shank.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
programming language system itself.