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=head1 NAME
HTML::FormHandler::Manual::Tutorial - use FormHandler with Catalyst
=head1 DESCRIPTION
A tutorial for beginners to L<HTML::FormHandler>
=head1 Using HTML::FormHandler with Catalyst
This tutorial demonstrates how you can use L<HTML::FormHandler>
to manage forms, validate form input, and interface your forms with the database.
=head1 Installation 
Use CPAN to install L<HTML::FormHandler> 
=head1 Use the Tutorial application
We'll use the files that were created in the L<Catalyst::Manual::Tutorial>, in
order to concentrate on just the bits where HTML::FormHandler is useful.
You can download a tar file of the tutorial files from the Catalyst
code repository. (See L<Catalyst::Manual::Tutorial::Intro>.)
=head2 Create an HTML::FormHandler form
Untar the tutorial and make a lib/MyApp/Form directory. In that directory 
create the file Book.pm.
   package MyApp::Form::Book;
   use HTML::FormHandler::Moose;
   extends 'HTML::FormHandler::Model::DBIC';
   has '+item_class' => ( default =>'Books' );
   has_field 'title' => ( type => 'Text' );
   has_field 'rating' => ( type => 'Integer' );
   has_field 'authors' => ( type => 'Multiple', label_column => 'last_name' );
   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 
L<HTML::FormHandler::Field> classes. 
'Text' and 'Integer' are types that are provided by HTML::FormHandler, 
in L<HTML::FormHandler::Field::Text> and L<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').
Eventually you will want to create your own field classes, but for 
this simple form the default types are adequate.
=head2 Connect HTML::FormHandler to your controller 
Edit lib/MyApp/Controller/Books.pm.  Add use Moose:
    BEGIN {
       use Moose;
       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 } );
=head2 Add Action to Display and Save the Form
In C<lib/MyApp/Controller/Books.pm> add the following method:
    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. 
=head2 Create a Template for the form 
L<HTML::FormHandler> provides only a simple sample 'render' routine to 
automatically create the HTML for your forms that you could use as
a model for creating your own rendering routines.
You could also use TT macros to do pretty sophisticated
template generation. But for now, we'll stick to a straightforward TT
template:
Open C<root/src/books/edit.tt2> in your editor 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="commit" type="submit" value="Submit" />
   </form>
     
   <p><a href="[% c.uri_for('list') %]">Return to book list</a></p>
=head2 Add links to access create and update actions
Add a link to root/src/books/list.tt2 to allow you to edit
an existing book, by changing the last <td> cell in the book
list:
   <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>
=head2 Test the L<HTML::FormHandler> Create Form
Start up the server for MyApp:
    $ 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.
=head2 Add additional attributes to your form's fields 
We'll add a couple of 'label' attribute to the 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' );
     
L<HTML::FormHandler> doesn't have built-in attributes for a submit button, but
if you want to put one in your form to use in a template, go ahead.
   has '+submit' => ( default => sub { { name => 'submit', value => 'Submit' }});
In a template, you could then access this with:
   <input class="button" name="[% form.submit.name %]" 
        type="[% form.submit.type %]" value="Submit" />
If you want all your forms to have a submit button definition, you can put this
in a base Form class. Or create a Moose::Role and group a number of similar
functions together.
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. 
=head1 L<HTML::FormHandler> Validation 
Now we'll add more validation to ensure that users
are entering correct data. 
Update the fields form file:
   has_field 'title' => ( type => 'Text', label => 'Title of a Book',
      required => 1, size => 40, min_length => 5 );
   has_field 'rating' => ( type => 'Integer', label => 'Rating (1-5)',
      required => 1, required_message => 'You must rate the book',
      range_start => 1, range_end => 5 );
   has_field 'authors' => ( type => 'Multiple', label_column => 'last_name',
      required => 1 );
We've made all the fields required.
We added 'size' and 'min_length' attributes to the 'title' field. These 
are attributes of the 'Text' Field, which will use them to validate.
We've added 'range_start' and 'range_end' attributes to the 'rating' field.
Numbers entered in the form will be checked to make sure they fall within
the defined range. (Another option would have been to use the 'IntRange'
field type, which makes it easy to create a select list of numbers.)
=head2 Add customized validation
Usually you would create a Field class for validation that will 
be performed on more than one field, but it is easy to perform
custom validation on a per-field basis.
This form doesn't really require any customized validation, 
so we'll add a silly validation routine.  Per-field validation routines 
are named "validate_" . $field_name, so add the following to
MyApp::Form::Book:
   sub validate_title {
      my ( $self, $field ) = @_;
      # Don't allow books with 'Rainbows' in the name 
      if ( $field->value =~ /Rainbows/ )
      {
          $field->add_error('The word \'Rainbows\' is not allowed in titles');
      }
   }
You can also have a 'cross_validation' routine to check interdependencies.
The 'validate_model' routine is the place to perform database specific validation.
You can validate that the field is unique, or use a dependency list to make
more fields required if one is updated.
=head2 Check out the validation 
Restart the development server, login, and try adding books with
various errors: title length less than 5 or more than 40, rating
above 5, leaving out a particular field.  Create a book with
'Rainbows' in the title.
You should get error messages for every error.
=head2 Database accessors
Although you can do database specific actions in a form class, you
should limit this to actions that won't be required for anything
except for your HTML forms. Other actions should be done in your 
L<DBIx::Class> classes. L<HTML::FormHandler::Model::DBIC> allows
the use of custom accessors, making it easier to keep the code
in the right place.
=head1 AUTHORS
Gerda Shank, gshank@cpan.org
=head1 COPYRIGHT
This library is free software, you can redistribute it and/or modify it under
the same terms as Perl itself.
=cut