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:

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.