[html-formfu] Patch to allow to provide a callback to "when" inside a Constraint

[Andreas Marienborg]

Could you make it so a callback also could be specified via the config- 
files? Since now it seems to expect a coderef, but perhaps a string  
pointing at a sub could also be allowed, or a class-name which should  
implement some method?

- andreas

On May 27, 2008, at 12:50 AM, Michele Beltrame wrote:

> Hi all!
>
> Attached is a small patch for HTML/FormFu/Constraint.pm which allows  
> to
> use a callback for "when" checks inside a constraint. This should  
> allow
> more complex control (i.e. based on multiple fields, external data,  
> etc...)
> on when the constraint is applied:
>
> my $is_blast = sub {
>     my $params = shift;
>
>     return 0 if $params->{isblastocyst} == 1 && $params->{old} == 1;
>
>     # Closure-style
>     return 0 if $c->model('Dbs::Atoms')->find($params->{old});
>
>     return 1;
> }
>
> [...]
>
> {
>     name    => 'embryos_day5',
>     type    => 'Text',
>     constraints => [{
>         type    => 'Number',
>         when    => {
>             callback => $is_blast,
>         },
>     }],
> },
>
> I'll provide tests if patch is considered a good idea to merge. ;-)
>
> Thanks,
> Michele.
>
> -- 
> Michele Beltrame
> http://www.cattlegrid.info/
> ICQ 76660101 - MSN mb at italpro.net
>
> --- home/mb/devel/formfu/trunk/HTML-FormFu/lib/HTML/FormFu/ 
> Constraint.pm
> +++ u/www/cheiron/cryo/Cryo/lib/HTML/FormFu/Constraint.pm
> @@ -107,29 +107,38 @@
>     # check type of 'when'
>     croak "Parameter 'when' is not a hash ref" if ref $when ne 'HASH';
>
> -    # field must be defined
> +    # field or callback must be defined
>     my $when_field = $when->{field};
> -    croak "Parameter 'field' is not defined" if !defined $when_field;
> -
> -    # nothing to constrain if field doesn't exist
> -    my $when_field_value = $params->{$when_field};
> -    return 0 if !defined $when_field_value;
> -
> -    # a compare value must be defined
> -    my @values;
> -    my $compare_value = $when->{value};
> -    push @values, $compare_value if defined $compare_value;
> -    my $compare_values = $when->{values};
> -    push @values, @$compare_values if ref $compare_values eq 'ARRAY';
> -    croak "Parameter 'value' or 'values' are not defined" unless  
> @values;
> -
> -    # determine if condition is fullfilled
> -    my $fullfilled = grep { $when_field_value eq $_ } @values;
> -
> -    # invert when condition if asked for
> -    $fullfilled = $when->{not} ? !$fullfilled : $fullfilled;
> -
> -    return $fullfilled;
> +    my $when_callback = $when->{callback};
> +    croak "Parameter 'field' or 'callback' is not defined"
> +        if !defined $when_field && !defined $when_callback;
> +
> +    # Callback will be the preferred thing
> +    if ( $when_callback ) {
> +        return $when_callback->($params);
> +    }
> +
> +    else {
> +        # nothing to constrain if field doesn't exist
> +        my $when_field_value = $params->{$when_field};
> +        return 0 if !defined $when_field_value;
> +
> +        # a compare value must be defined
> +        my @values;
> +        my $compare_value = $when->{value};
> +        push @values, $compare_value if defined $compare_value;
> +        my $compare_values = $when->{values};
> +        push @values, @$compare_values if ref $compare_values eq  
> 'ARRAY';
> +        croak "Parameter 'value' or 'values' are not defined"  
> unless @values;
> +
> +        # determine if condition is fullfilled
> +        my $fullfilled = grep { $when_field_value eq $_ } @values;
> +
> +        # invert when condition if asked for
> +        $fullfilled = $when->{not} ? !$fullfilled : $fullfilled;
> +
> +        return $fullfilled;
> +    }
> }
>
> 1;
> @@ -259,6 +268,10 @@
>   value: expected value in the form field 'field'
>   values: Array of multiple values, one must match to fullfill the  
> condition
>   not: inverse the when condition - value(s) must not match
> +  callback: a callback can be supplied to perform complex checks.  
> An hashref
> +    of all parameters is passed. In this case all other keys are  
> ignored,
> +    including not. Return a true value for the constraint to be  
> valid or
> +    a false value to not apply it.
>
> =head1 CORE CONSTRAINTS
>
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