HTML::FormFu::Constraint(3p)

NAME
HTML::FormFu::Constraint - Constrain User Input

VERSION
version 2.07

SYNOPSIS
    ---
    elements:
      - type: Text
        name: foo
        constraints:
          - type: Length
            min: 8
            when:
              field: bar
              values: [ 1, 3, 5 ]
      - type: Text
        name: bar
        constraints:
          - Integer
          - Required
    constraints:
      - SingleValue

DESCRIPTION
User input is processed in the following order:

Filters
Constraints
Inflators
Validators
Transformers

See "FORM LOGIC AND VALIDATION" in HTML::FormFu for further details.

"constraints" in HTML::FormFu can be called on any form, block element (includes fieldsets) or field element.

If called on a field element, no "name" argument should be passed.

If called on a form or block element, if no "name" argument is provided, a new constraint is created for and added to every field on that form or block.

See "FORM LOGIC AND VALIDATION" in HTML::FormFu for further details.

METHODS

  type
Returns the "type" argument originally used to create the constraint.

  not
If true, inverts the results of the constraint - such that input that would otherwise fail will pass, and vise-versa.

This value is ignored by some constraints - see the documentation for individual constraints for details.

  only_on_reps
Argument: \@repeatable_count

For constraints added to fields within a Repeatable element, if "only_on_reps" is set, the constraint will only be run for fields whose repeatable_count matches one of these set values.

Not available for the constraints listed in "Unsupported Constraints" in HTML::FormFu::Element::Repeatable.

  message
Arguments: $string

Set the message which will be displayed if the constraint fails.

  message_xml
Arguments: $string

Variant of "message" which ensures the value won't be XML-escaped.

  message_loc
Arguments: $string

Variant of "message" which uses localize to create the message.

  localize_args
Provide arguments that should be passed to localize to replace "[_1]", "[_2]", etc. in the localized string.

  force_errors
See "force_errors" in HTML::FormFu for details.

  parent
Returns the field object that the constraint is associated with.

  form
Returns the HTML::FormFu object that the constraint's field is attached to.

  name
Shorthand for "$constraint->parent->name"

  when
Defines a condition for the constraint. Only when the condition is fulfilled the constraint will be applied.

This method expects a hashref.

The "field" or "callback" must be supplied, all other fields are optional.

If "value" or "values" is not supplied, the constraint will pass if the named field's value is true.

The following keys are supported:

field
    Nested-name of form field that shall be checked against - if "when->{value}" is set, the "when" condition passes if the named field's value matches that, otherwise the "when" condition passes if the named field's value is true.

fields
    Array-ref of nested-names that shall be checked. The "when" condition passes if all named-fields' values pass, using the same rules as "field" above.

any_field
    Array-ref of nested-names that shall be checked. The "when" condition passes if any named-fields' values pass, using the same rules as "field" above.

value
    Expected value in the form field 'field'

values
    Array of multiple values, one must match to fulfill the condition

not Inverts the when condition - value(s) must not match

callback
    A callback subroutine-reference or fully resolved subroutine name can be supplied to perform complex checks. An hashref of all parameters is passed to the callback sub. In this case all other keys are ignored, including "not". You need to return a true value for the constraint to be applied or a false value to not apply it.

    The callback subroutine receives 2 arguments:

    1.  $params (hashref of all submitted parameters)

    2.  $constraint (the Constraint object)

EXPERIMENTAL METHODS

  fetch_error_message
Return value: $string

Attempt to return the error message that would be used if this constraint generated an error.

This will generally be correct for simple constraints with a fixed message or which use a placeholder from a known value, such as "min" in HTML::FormFu::Constraint::Min. This will generally "not" return the correct message for constraints which use "others" in HTML::FormFu::Role::Constraint::Others, where the field with an error is not known without actually fully processing a form submission.

CORE CONSTRAINTS

HTML::FormFu::Constraint::AllOrNone
HTML::FormFu::Constraint::ASCII
HTML::FormFu::Constraint::AutoSet
HTML::FormFu::Constraint::Bool
HTML::FormFu::Constraint::Callback
HTML::FormFu::Constraint::CallbackOnce
HTML::FormFu::Constraint::DateTime
HTML::FormFu::Constraint::DependOn
HTML::FormFu::Constraint::Email
HTML::FormFu::Constraint::Equal
HTML::FormFu::Constraint::File
HTML::FormFu::Constraint::File::MIME
HTML::FormFu::Constraint::File::MaxSize
HTML::FormFu::Constraint::File::MinSize
HTML::FormFu::Constraint::File::Size
HTML::FormFu::Constraint::Integer
HTML::FormFu::Constraint::JSON
HTML::FormFu::Constraint::Length
HTML::FormFu::Constraint::MaxLength
HTML::FormFu::Constraint::MaxRange
HTML::FormFu::Constraint::MinLength
HTML::FormFu::Constraint::MinRange
HTML::FormFu::Constraint::MinMaxFields
HTML::FormFu::Constraint::Number
HTML::FormFu::Constraint::Printable
HTML::FormFu::Constraint::Range
HTML::FormFu::Constraint::Regex
HTML::FormFu::Constraint::Required
HTML::FormFu::Constraint::Set
HTML::FormFu::Constraint::SingleValue
HTML::FormFu::Constraint::Word

NON-CORE CONSTRAINTS AVAILABLE ON CPAN

HTML::FormFu::Constraint::reCAPTCHA

CAVEATS
See "Unsupported Constraints" in HTML::FormFu::Element::Repeatable for a list of constraints that won't work within HTML::FormFu::Element::Repeatable.

AUTHOR
Carl Franks, "cfranks@cpan.org"

Based on the original source code of HTML::Widget::Constraint, by Sebastian Riedel, "sri@oook.de".

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.