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


This is Chapter 9 of 10 for the Catalyst tutorial.
Tutorial Overview
Catalyst Basics
More Catalyst Basics
Basic CRUD
09_Advanced CRUD::09_FormHandler


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".


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/":
    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' );

Add Action to Display and Save the Form

At the top of the "lib/MyApp/Controller/" add:
   use MyApp::Form::Book;
Add the following methods:
    =head2 create
    Use HTML::FormHandler to create a new book
    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
    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
            {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>
Open "root/src/books/list.tt2" in your editor and add the following to the bottom of the existing file:
      <a href="[% c.uri_for(c.controller.action_for('create')) %]">Create</a>
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/
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/" 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/
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/" and add the following method:
    =head2 edit
    Edit an existing book with  FormHandler
    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:
      [% # Add a link to delete a book %]
      <a href="[% c.uri_for(c.controller.action_for('delete'), []) %]">Delete</a>
      [% # Add a link to edit a book %]
      <a href="[% c.uri_for(c.controller.action_for('edit'), []) %]">Edit</a>

Try Out the Edit/Update Feature

Press "Ctrl-C" to kill the previous server instance (if it's still running) and restart it:
    $ script/
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

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Gerda Shank, ""
Copyright 2009, Gerda Shank, Perl Artistic License
2017-08-02 perl v5.26.0