---
name: "HTML::FormFu::Constraint::Callback"
section: "3pm"
platform: "linux"
package: "libhtml-formfu-perl"
version: "2.07000-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/HTML::FormFu::Constraint::Callback"
---

# HTML::FormFu::Constraint::Callback(3pm)

Code Callback Constraint

## NAME

HTML::FormFu::Constraint::Callback - Code Callback Constraint

## VERSION

version 2.07

## SYNOPSIS

```
    $field->constraint({
        type => 'Callback',
        callback => \&foo,
    });
    ---
    elements:
      - type: Text
        name: foo
        constraints:
          - type: Callback
            callback: "main::my_constraint"
    sub foo {
        my ( $value, $params ) = @_;
        # return true or false
    }
```

## DESCRIPTION

The first argument passed to the callback is the submitted value for the associated field. The second argument passed to the callback is a hashref of name/value pairs for all input fields.

This constraint doesn't honour the `not()` value.

## METHODS

### callback

Arguments: \\&code-reference

Arguments: "subroutine-name"

## SEE ALSO

Is a sub-class of, and inherits methods from HTML::FormFu::Constraint

HTML::FormFu

## AUTHOR

Carl Franks `"cfranks@cpan.org"`

## LICENSE

This library is free software, you can redistribute it and/or modify it under the same terms as Perl itself.

## AUTHOR

Carl Franks \<cpan@fireartist.com\>

## COPYRIGHT AND LICENSE

This software is copyright (c) 2018 by Carl Franks.

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