Devin Austin > Form-Sensible-Reflector-0.01 > Form::Sensible::Reflector

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Module Version: 0.01   Source  

$self->with_trigger

Add a submit button to the form. Defaults to 0.

NAME ^

Form::Sensible::Reflector - A base class for writing Form::Sensible reflectors.

VERSION ^

version 0.01

SYNOPSIS ^

    my $reflector = Form::Sensible::Reflector::SomeSubclass->new();

    my $generated_form = $reflector->reflect_from($data_source, $options);

DESCRIPTION ^

A Reflector in Form::Sensible is a class that inspects a data source and creates a form based on what it finds there. In other words it creates a form that 'reflects' the data elements found in the data source.

A good example of this would be to create forms based on a DBIx::Class result_source (or table definition.) Using the DBIC reflector, you could create form for editing a user's profile information simply by passing the User result_source into the reflector.

This module is a base class for writing reflectors, meaning you do not use this class directly. Instead you use one of the subclasses that deal with your data source type.

USAGE ^

    my $reflector = Form::Sensible::Form::Reflector::SomeSubclass->new();

    my $generated_form = $reflector->reflect_from($data_source, $options);

By default, a Reflector will create a new form using the exact fields found within the datasource. It is possible, however, to adjust this behavior using the $options hashref passed to the reflect_from call.

Adjusting the parameters of your new form

    my $generated_form = $reflector->reflect_from($data_source, 
                                                  { 
                                                    form => {
                                                        name => 'profile_form',
                                                        validation => { 
                                                            code => sub { ... }
                                                        }
                                                    }
                                                  });

If you want to adjust the parameters of the new form, you can provide a hashref in the $options->{form} that will be passed to the Form::Sensible::Form->new() call.

Providing your own form

    $reflector->reflect_from($data_source, 
                            { 
                                form => $my_existing_form_object
                            }
                            );

If you do not want to create a new form, but instead want the fields appended to an existing form, you can provide an existing form object in the options hash ( $options->{form} )

Adding additional fields

    $reflector->reflect_from($data_source, 
                            {
                                additional_fields => [
                                                {
                                                    field_class => 'Text',
                                                    name => 'process_token',
                                                    render_hints => {
                                                        field_type => 'hidden',
                                                    }
                                                },
                                                {
                                                    field_class => 'Trigger',
                                                    name => 'submit'
                                                }
                                            ]
                            }

This allows you to add fields to your form in addition to the ones provided by your data source. It also allows you to override your data source, as any additional field with the same name as a reflected field will take precedence over the reflected field. This is also a good way to automatically add triggers to your form, such as a 'submit' or 'save' button.

NOTE: The reflector base class used to add a submit button automatically. The additional_fields mechanism replaces that functionality. This means your reflector call needs to add the submit button, as shown above, or it needs to be added programmatically later.

Changing field order

    $reflector->reflect_from($data_source, 
                            { 
                                ## sort fields alphabetically
                                fieldname_filter => sub { 
                                                        return sort(@_);
                                                    },
                            }
                            );

If you are unhappy with the order that your fields are displaying in you can adjust it by providing a subroutine in $options->{'fieldname_filter'}. The subroutine takes the list of fields as returned by get_fieldnames() and should return an array (not an array ref) of the fields in the new order. Note that you can also remove fields this way. Note also that no checking is done to verify that the fieldnames you return are valid, if you return any fields that were not in the original array, you are likely to cause an exception when the field definition is created.

Changing field names

$reflector->reflect_from($data_source, { ## change 'logon' field to be 'username' in the form ## and other related adjustments. fieldname_map => { logon => 'username', pass => 'password', address => 'email', home_num => 'phone', parent_account => undef, }, } );

By default, the Form::Sensible field names are exactly the same as the data source's feild names. If you would rather not expose your internal field names or have other reason to change them, you can provide a $options->{'fieldname_map'} hashref to change them on the fly. The fieldname_map is simply an mapping between the original field name and the Form::Sensible field name you would like it to use. If you use this method you must provide a mapping for ALL fields as a missing field (or a field with an undef value) is treated as a request to remove the field from the form entirely.

CREATING YOUR OWN REFLECTOR ^

Creating a new reflector class is extraordinarily simple. All you need to do is create a subclass of Form::Sensible::Reflector and then create two subroutines: get_fieldnames and get_field_definition.

As you might expect, get_fieldnames should return an array containing the names of the fields that are to be created. get_field_definition is then called for each field to be created and should return a hashref representing that field suitable for passing to the Form::Sensible::Field create_from_flattened method.

Note that in both cases, the contents of $datasource are specific to your reflector subclass and are not inspected in any way by the base class.

Subclass Boilerplate

    package My::Reflector;
    use Moose;
    use namespace::autoclean;
    extends 'Form::Sensible::Reflector';

    sub get_fieldnames {
        my ($self, $form, $datasource) = @_;
        my @fieldnames;
        
        foreach my $field ($datasource->the_way_to_get_all_your_fields()) {
            push @fieldnames, $field->name;
        }
        return @fieldnames;
    }

    sub get_field_definition { 
        my ($self, $form, $datasource, $fieldname) = @_;
        
        my $field_definition = {
            name => $fieldname
        };
        
        ## inspect $datasource's $fieldname and add things to $field_definition
        
        return $field_definition;
    }

Note that while the $form that your field will likely be added to is available for inspection, your reflector should NOT make changes to the passed form. It is present for inspection purposes only. If your module DOES have a reason to look at $form, be aware that in some cases, such as when only the field definitions are requested, $form will be null. Your reflector should do the sensible thing in this case, namely, not crash.

Customizing the forms your reflector creates

If you need to customize the form object that your reflector will return, there are two methods that Form::Sensible::Reflector will look for. You only need to provide these in your subclass if you need to modify the form object itself. If not, the default behaviors will work fine. The first is create_form_object which Form::Sensible::Reflector calls in order to instantiate a form object. It should return an instantiated Form::Sensible::Form object. The default create_form_object method simply passes the provided arguments to the Form::Sensible::Form's new call:

 sub create_form_object {
     my ($self, $handle, $form_options) = @_;

     return Form::Sensible::Form->new($form_options);
 }

Note that this will NOT be called if the user provides a form object, so if special adjustments are absolutely required, you should consider making those changes using the finalize_form method described below.

The second method is finalize_form. This method is called after the form has been created and all the fields have been added to the form. This allows you to do any final form customization prior to the form actually being used. This is a good way to add whole-form validation, for example:

 sub finalize_form {
     my ($self, $form, $handle) = @_;

     return $form;
 }

Note that the finalize_form call must return a form object. Most of the time this will be the form object passed to the method call. The return value of finalize_form is what is returned to the user calling reflect_from.

Author's note

This is a base class to write reflectors for things like, configuration files, or my favorite, a database schema.

The idea is to give you something that creates a form from some other source that already defines form-like properties, ie a database schema that already has all the properties and fields a form would need.

I personally hate dealing with forms that are longer than a search field or login form, so this really fits into my style.

AUTHORS ^

Devin Austin <dhoss@cpan.org> Jay Kuri <jayk@cpan.org>

ACKNOWLEDGEMENTS ^

Jay Kuri <jayk@cpan.org> for his awesome Form::Sensible library and helping me get this library in tune with it.

SEE ALSO ^

Form::Sensible Form::Sensible Wiki: http://wiki.catalyzed.org/cpan-modules/form-sensible Form::Sensible Discussion: http://groups.google.com/group/formsensible

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