An overview of HTML::FormHandler, a Moose-based form rendering, processing and validation framework for Perl.

1. HTML::FormHandler Bryan Beeley Reach Systems www.reachsystems.com

2. Quick Moose Review Overview Functional Examples Real World Examples Limitations

3. Quick Moose Review Object Framework Simple Attribute/Accessor Creation Method Modifiers

4. Object Framework package MooseOb; use Moose; ... no Moose; package DerivedOb; use Moose; extends 'MooseOb'; ... no Moose; my $ob = DerivedOb->new; Moose

5. Moose Simple Attribute/Accessor Creation has 'attribute' => ( # Properties is => 'rw', # Attribute is read/write isa => 'Str', # Indicate a type ); … $obj->attribute('value'); … $val = $obj->attribute();

6. Moose Method Modifiers package Base; use Moose; sub method { print “inside”; } package Derived; use Moose; extends 'Base'; before 'method' => sub { print “before”; }; around 'method' => sub { my $orig = shift; my $self = shift; print “around”; $self->$orig(@_); # prints inside print “around”; }; after 'method' => sub { print “after”; };

7. HTML::FormHandler Overview HFH and MVC Forms Simple Example Object Creation Parameter Processing Validation Failed Validation Form Rendering Updating the Data Model Repeatable Fields

8. Model View Controller Form? HFH and MVC

10. Name

12. Input

13. Validated

15. Name – An attribute of the field object

17. Input – Separate Attribute (associted with a result object)

18. Validated – Separate Attribute

19. package Form; use HTML::FormHandler::Moose; extends 'HTML::FormHandler'; has_field 'column_name' => ( type => 'Text' ); has_field 'submit' => ( type => 'Submit' ); no HTML::FormHandler::Moose; … my $form = Form->new( item => $object ); $form->process( $params ); if ($form->validated) { # Form submitted successfully } else { $output = $form->render; }

20. package Form; use HTML::FormHandler::Moose; extends 'HTML::FormHandler::Model::DBIC'; use namespace::autoclean; has_field 'column_name' => ( type => 'Text' ); has_field 'submit' => ( type => 'Submit' ); __PACKAGE__->make_immutable; … my $form = Form->new( item => $dbic_row_ob ); $form->process( $c->req->parameters ); if ($form->validated) { # Redirect or something } else { my $output = $form->render; $c->stash->{template} = output; }

24. $form->process; $form->process( $params ); my $success = $form->process( params => $params, arg => $arg, ); Parses form data out of parameters Saves input data in field objects Validates input data Generates error messages if appropriate Parameter Processing

25. Validation Default has_field 'number' => ( type => 'Integer', required => 1, ); In your form class has_field 'no_spaces' => ( type => 'Text' ); sub validate_no_spaces { my ($self, $field) = @_; $form->add_error('Must not have spaces') if $field->value =~ //; } In your field class sub validate { my $self = shift; ... $self->add_error('My custom message') if $error; }

26. Failed Validation Check the process return value my $success = $form->process; Add an error message $field->add_error('Error message'); Check a form for errors if ($form->has_errors) { … } Check a field for errors if ($field->has_errors) { … } Get form error messages my @error_messages = $form->errors;

27. Form Rendering Render into a scalar using HFH widgets my $output = $form->render; Render in a Template Toolkit template using HFH widgets [% form.render %] Let Template Toolkit do the work [% f = form.field('my_text_field') %] Enter some text: <input type=”text” name=”[% f.html_name %]” value=”[% f.html_filter(f.fif) %]” />

28. Updating the Data Model Use the HFH Model Interface in your form extends 'HTML::FormHandler::Model::DBIC'; Roll your own form update_model method sub update_model { … } Use any object that with accessors matching field names $form->process( item => $object, params => $params );

29. Repeatable Fields has_field 'order_id' => ( type => 'PosInteger' ); has_field 'cart_items' => ( type => 'Repeatable' ); has_field 'cart_items.cost' => ( type => 'Money' ); has_field 'cart_items.name' => ( type => 'Text' ) ; … JavaScript to dynamically add items to the cart … DBIC extension will submit rows into the related table

30. Functional Examples

31. Real World Examples

32. Default rendering is very primitive HFH DBIC model has problems in some cases Repeatable fields forget initial values new and process do the same thing twice Limitations

33. Workarounds and Solutions Override render, or create your own widgets Write your own update_model Patches are welcome Cache form objects