Create an HTML::FormHandler form

   package MyApp::Form::Book;

   use utf8; # if using non-latin1 languages

   use HTML::FormHandler::Moose;
   extends 'HTML::FormHandler::Model::DBIC';

   has '+item_class' => ( default => 'Book' );
   has_field 'title' => ( type => 'Text' );
   has_field 'rating' => ( type => 'Integer' );
   has_field 'authors' => ( type => 'Multiple', label_column => 'last_name' );
   has_field 'submit' => ( type => 'Submit', value => 'Submit' );

   no HTML::FormHandler::Moose;
   1;

This is your Form class. The form initializes the 'item_class' to the source name of your DBIx::Class result class. The form's fields are defined with the 'has_field' sugar, or in a 'field_list'. The names of the fields should match a column, relationship, or other accessor in your DBIx::Class result class.

The basic fields have only a 'type', such as 'Text', or 'Integer'. These types are actually the names of HTML::FormHandler::Field classes. 'Text' and 'Integer' are types that are provided by HTML::FormHandler, in HTML::FormHandler::Field::Text and HTML::FormHandler::Field::Integer.

The 'Multiple' type will allow you to easily create a multiple select list from the 'authors' relationship. The 'label_column' attribute must be defined because the column in the 'authors' table which is used to create the select list does not have the default column name ('name').

The 'submit' field is necessary if you are going to use FormHandler to render your form. It wouldn't be necessary for hand-built templates or HTML.

Eventually you will want to create your own field classes, but for this simple form the default types are adequate.

Connect HTML::FormHandler to your controller

    use Moose;
    BEGIN { extends 'Catalyst::Controller' }
    use MyApp::Form::Book;

Create an attribute to hold your form:

   has 'form' => ( isa => 'MyApp::Form::Book', is => 'rw',
       lazy => 1, default => sub { MyApp::Form::Book->new } );

Add Action to Display and Save the Form

    sub edit : Local {
        my ( $self, $c, $book_id ) = @_;

        $c->stash( template => 'books/edit.tt2',
                   form => $self->form );

        # Validate and insert/update database
        return unless $self->form->process( item_id => $book_id,
           params => $c->req->parameters,
           schema => $c->model('DB')->schema );

        # Form validated, return to the books list
        $c->flash->{status_msg} = 'Book saved';
        $c->res->redirect($c->uri_for('list'));
    }

This will handle both creating new books, and updating old books. If $book_id is undefined, then HTML::FormHandler will create a new book from your form. If you pass in a DBIx::Class row object instead of a primary key, you don't need to specify the schema.

Render the form

   [% form.render %]

Alternative hand-built Template for the form (optional)

In some cases, you might want to use the rendering for just the field and build custom divs or tables or whatever around it:

  <div class="mycustomclass">
  [% form.render_field('book') %]
  </div>

If you don't want to play with HTML at this point, you can skip ahead to the next section.

You could also use TT macros to do pretty sophisticated template generation. But for now, we'll stick to a straightforward TT template:

Delete the single statement in "root/src/books/edit.tt2", and enter or copy the following:

   [% META title = 'Book Form' %]

   [% FOR field IN form.error_fields %]
     [% FOR error IN field.errors %]
       <p><span class="error" id="error">
          [% field.label _ ': ' _ error %] </span></p>
     [% END %]
   [% END %]

   <form name="[% form.name %]"
         action="[% c.uri_for('edit', form.item_id) %]"
         method="post">
   <p>
   [% f = form.field('title') %]
   <label class="label" for="[% f.name %]">[% f.label %]:</label>
   <input type="text" name="[% f.name %]" id="[% f.name %]" value="[% f.fif %]">
   </p>
   <p>
   [% f = form.field('rating') %]
   <label class="label" for="[% f.name %]">[% f.label %]:</label>
   <input type="text" name="[% f.name %]" id="[% f.name %]" %] value="[% f.fif %]">
   </p>
   <p>
   [% f = form.field('authors') %]
   <label class="label" for="[% f.name %]">[% f.label %]:</label>
   <select name="[% f.name %]" multiple="multiple" size="[% f.size %]">
     [% FOR option IN f.options %]
       <option value="[% option.value %]"
         [% FOREACH selval IN f.fif %]
             [% IF selval == option.value %]selected="selected"[% END %]
         [% END %]>
       [% option.label | html %]</option>
     [% END %]
   </select>
   </p>
   <input class="button" name="submit" type="submit" value="Submit" />
   </form>

   <p><a href="[% c.uri_for('list') %]">Return to book list</a></p>

Add links to access create and update actions

   <td>
      <a href="[% c.uri_for('delete', book.id) %]">Delete</a>|
      <a href="[% c.uri_for('edit', book.id) %]">Edit</a>
   </td>

Change the link to create a book at the bottom of the file:

    <p>
      <a href="[% c.uri_for('edit') %]">Create book</a>
    </p>

Test the HTML::FormHandler Create Form

    $ script/myapp_server.pl

(You'll need to login with test01/mypass if you're using the packaged tutorial.) Click the new "Create book" link at the bottom to display the form. Fill in the fields and click submit. You should be returned to the Book List page with a "Book saved" message.

Magic! A new book has been created and saved to the database with very little code in your controller.

Click on the 'edit' links, and edit the existing books. Changes should be saved and displayed properly. Try to add an alphabetic character to the rating field. You should get an error message.

Add additional attributes to your form's fields

   has_field 'title' => ( type => 'Text', label => 'Title of a Book' );
   has_field 'rating' => ( type => 'Integer', label => 'Rating (1-5)' );
   has_field 'authors' => ( type => 'Multiple', label_column => 'last_name' );

If you want a new attribute in your fields, it's very easy to add it to your custom Field classes.

   package MyApp::Form::Field::Extra;
   use Moose;
   extends 'HTML::FormHandler::Field';

   has 'my_attribute' => ( isa => Str, is => 'ro' );

   1;

Now if your Field classes inherit from this, you can have a 'my_attribute' attribute for all your fields. Or use a Moose role instead of inheritance.

You can also add attributes to the base FormHandler field class using Moose. This technique is described in HTML::FormHandler::Manual::Cookbook.

Add customized validation

This form doesn't really require any customized validation, so we'll add a silly field constraint. Add the following to the form:

   sub validate_title {
      my ( $self, $field ) = @_;
      $field->add_error("The word \'Rainbows\' is not allowed in titles")
         if ( $field->value =~ /Rainbows/ );
   }

You can also apply Moose constraints and transforms. Validation can also be performed in a form 'validate_<field_name' method, in a 'validate_model' routine, and in a custom field class. You can validate that the field is unique, or use a dependency list to make more fields required if one is updated.

Check out the validation

You should get error messages for every error.