Provided by: libhtml-formhandler-perl_0.40068-1_all 
NAME
HTML::FormHandler::Manual::Tutorial - how to use FormHandler with Catalyst
VERSION
version 0.40068
SYNOPSIS
Manual Index
A tutorial for beginners to HTML::FormHandler
Using HTML::FormHandler with Catalyst
This tutorial demonstrates how you can use HTML::FormHandler to manage forms, validate
form input, and interface your forms with the database.
Installation
Use CPAN to install HTML::FormHandler
Use the Tutorial application
We'll use the files that were created in the 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
Catalyst::Manual::Tutorial::Intro.)
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 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
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 } );
Add Action to Display and Save the Form
In "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.
Render the form
Save a copy of "root/src/books/edit.tt2" and create a new file that contains only:
[% form.render %]
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 "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
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>
Test the 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.
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 HTML::FormHandler::Manual::Cookbook.
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.)
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.
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.
AUTHOR
FormHandler Contributors - see HTML::FormHandler
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.