Catalyst::Manual::Tutorial::09_AdvancedCRUD::09_FormHandler(3)

NAME
Catalyst::Manual::Tutorial::09_AdvancedCRUD::09_FormHandler - Catalyst Tutorial - Chapter 9: Advanced CRUD - FormHandler

OVERVIEW
This is Chapter 9 of 10 for the Catalyst tutorial.

Tutorial Overview

1.  Introduction

2.  Catalyst Basics

3.  More Catalyst Basics

4.  Basic CRUD

5.  Authentication

6.  Authorization

7.  Debugging

8.  Testing

9.  09_Advanced CRUD::09_FormHandler

10. Appendices

DESCRIPTION
This portion of the tutorial explores HTML::FormHandler and how it can be used to manage forms, perform validation of form input, and save and restore data to or from the database. This was written using HTML::FormHandler version 0.28001.

See Catalyst::Manual::Tutorial::09_AdvancedCRUD for additional form management options other than HTML::FormHandler.

Install HTML::FormHandler
Use the following command to install HTML::FormHandler::Model::DBIC directly from CPAN:

    sudo cpan HTML::FormHandler::Model::DBIC

It will install HTML::FormHandler as a prerequisite.

Also, add:

    requires 'HTML::FormHandler::Model::DBIC';

to your Makefile.PL.

HTML::FormHandler FORM CREATION
This section looks at how HTML::FormHandler can be used to add additional functionality to the manually created form from Chapter 4.

  Using FormHandler in your controllers
FormHandler doesn't have a Catalyst base controller, because interfacing to a form is only a couple of lines of code.

  Create a Book Form
Create the directory lib/MyApp/Form. Create lib/MyApp/Form/Book.pm:

    package MyApp::Form::Book;

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

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

    __PACKAGE__->meta->make_immutable;
    1;

  Add Action to Display and Save the Form
At the top of the lib/MyApp/Controller/Books.pm add:

   use MyApp::Form::Book;

Add the following methods:

    =head2 create

    Use HTML::FormHandler to create a new book

    =cut

    sub create : Chained('base') PathPart('create') Args(0) {
        my ($self, $c ) = @_;

        my $book = $c->model('DB::Book')->new_result({});
        return $self->form($c, $book);
    }

    =head2 form

    Process the FormHandler book form

    =cut

    sub form {
        my ( $self, $c, $book ) = @_;

        my $form = MyApp::Form::Book->new;
        # Set the template
        $c->stash( template => 'books/form.tt2', form => $form );
        $form->process( item => $book, params => $c->req->params );
        return unless $form->validated;
        # Set a status message for the user & return to books list
        $c->response->redirect($c->uri_for($self->action_for('list'),
            {mid => $c->set_status_msg("Book created")}));
    }

These two methods could be combined at this point, but we'll use the 'form' method later when we implement 'edit'.

  Create a Template Page To Display The Form
Open root/src/books/form.tt2 in your editor and enter the following:

    [% META title = 'Create/Update Book' %]

    [%# Render the HTML::FormHandler Form %]
    [% form.render %]

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

  Add Link for Create
Open root/src/books/list.tt2 in your editor and add the following to the bottom of the existing file:

    ...
    <p>
        HTML::FormHandler:
        <a href="[% c.uri_for(c.controller.action_for('create')) %]">Create</a>
    </p>

This adds a new link to the bottom of the book list page that we can use to easily launch our HTML::FormHandler-based form.

  Test The HTML::FormHandler Create Form
Press "Ctrl-C" to kill the previous server instance (if it's still running) and restart it:

    $ script/myapp_server.pl

Login as "test01" (password: mypass). Once at the Book List page, click the new HTML::Formhandler "Create" link at the bottom to display the form. Fill in the following values:

    Title  = "Internetworking with TCP/IP Vol. II"
    Rating = "4"
    Author = "Comer"

Click the Submit button, and you will be returned to the Book List page with a "Book created" status message displayed.

Note that because the 'Author' column is a Select list, only the authors in the database can be entered. The 'ratings' field will only accept integers.

  Add Constraints
Open lib/MyApp/Form/Book.pm in your editor.

Restrict the title size and make it required:

   has_field 'title' => ( minlength => 5, maxlength => 40, required => 1 );

Add range constraints to the 'rating' field:

   has_field 'rating' => ( type => 'Integer', range_start => 1, range_end => 5 );

The 'authors' relationship is a 'many-to-many' pseudo-relation, so this field can be set to Multiple to allow the selection of multiple authors; also, make it required:

   has_field 'authors' => ( type => 'Multiple', label_column => 'last_name',
                            required => 1 );

Note: FormHandler automatically strips whitespace at the beginning and end of fields. If you want some other kind of stripping (or none) you can specify it explicitly; see HTML::FormHandler::Manual.

  Try Out the Updated Form
Press "Ctrl-C" to kill the previous server instance (if it's still running) and restart it:

    $ script/myapp_server.pl

Make sure you are still logged in as "test01" and try adding a book with various errors: title less than 5 characters, non-numeric rating, a rating of 0 or 6, etc. Also try selecting one, two, and zero authors.

  Create the 'edit' method
Edit lib/MyApp/Controller/Books.pm and add the following method:

    =head2 edit

    Edit an existing book with  FormHandler

    =cut

    sub edit : Chained('object') PathPart('edit') Args(0) {
        my ( $self, $c ) = @_;

        return $self->form($c, $c->stash->{object});
    }

Update the root/src/books/list.tt2, adding an 'edit' link below the "Delete" link to use the FormHandler edit method:

    <td>
        [% # Add a link to delete a book %]
        <a href="[% c.uri_for(c.controller.action_for('delete'), [book.id]) %]">Delete</a>
        [% # Add a link to edit a book %]
        <a href="[% c.uri_for(c.controller.action_for('edit'), [book.id]) %]">Edit</a>
    </td>

  Try Out the Edit/Update Feature
Press "Ctrl-C" to kill the previous server instance (if it's still running) and restart it:

    $ script/myapp_server.pl

Make sure you are still logged in as "test01" and go to the <http://localhost:3000/books/list> URL in your browser. Click the "Edit" link next to "Internetworking with TCP/IP Vol. II", change the rating to a 3, the "II" at end of the title to the number "2", add Stevens as a co-author (control-click), and click Submit. You will then be returned to the book list with a "Book edited" message at the top in green. Experiment with other edits to various books.

  See additional documentation on FormHandler
HTML::FormHandler::Manual

HTML::FormHandler

   #formhandler on irc.perl.org

   mailing list: http://groups.google.com/group/formhandler

   code: http://github.com/gshank/html-formhandler/tree/master

AUTHOR
Gerda Shank, "gshank@cpan.org"

Copyright 2009, Gerda Shank, Perl Artistic License