package HTML::FormHandler::Manual::Tutorial;
# ABSTRACT: how to use FormHandler with Catalyst

__END__

=pod

=encoding UTF-8

=head1 NAME

HTML::FormHandler::Manual::Tutorial - how to use FormHandler with Catalyst

=head1 VERSION

version 0.40068

=head1 SYNOPSIS

L<Manual Index|HTML::FormHandler::Manual>

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 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
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').

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.

=head2 Connect HTML::FormHandler to your controller

Edit lib/MyApp/Controller/Books.pm.  Add use Moose:

    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 } );

=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 Render the form

Save a copy of C<root/src/books/edit.tt2> and create a new file that
contains only:

   [% form.render %]

=head2 Alternative hand-built Template for the form (optional)

Although the automatic rendering works well, sometimes it's necessary
to hand build HTML. This section contains an example of a Template Toolkit
template that may be used to display a FormHandler form.

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 C<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>

=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' attributes 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' );

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 L<HTML::FormHandler::Manual::Cookbook>.

=head1 L<HTML::FormHandler> Validation

Now we'll add more validation to ensure that users
are entering correct data.

Update the fields in the form file:

   has_field 'title' => ( type => 'Text', label => 'Title of a Book',
      required => 1, size => 40, minlength => 5 );
   has_field 'rating' => ( type => 'Integer', label => 'Rating (1-5)',
      required => 1, messages => { required => '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 'minlength' 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

You can 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 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.

=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.

=head1 AUTHOR

FormHandler Contributors - see HTML::FormHandler

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2017 by Gerda Shank.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut