Inherit From Catalyst::Controller::HTML::FormFu¶

First, change your lib/MyApp/Controller/Books.pm to inherit from Catalyst::Controller::HTML::FormFu by changing the "extends" line from the default of:

    BEGIN {extends 'Catalyst::Controller'; }

to use the FormFu base controller class:

    BEGIN {extends 'Catalyst::Controller::HTML::FormFu'; }

Don't forget to add:

    requires 'HTML::FormFu';
    requires 'Catalyst::Controller::HTML::FormFu';
    requires 'HTML::FormFu::Model::DBIC';

to your "Makefile.PL".

Add Action to Display and Save the Form¶

Open lib/MyApp/Controller/Books.pm in your editor and add the following method:

    =head2 formfu_create
    Use HTML::FormFu to create a new book
    =cut
    sub formfu_create :Chained('base') :PathPart('formfu_create') :Args(0) :FormConfig {
        my ($self, $c) = @_;
        # Get the form that the :FormConfig attribute saved in the stash
        my $form = $c->stash->{form};
        # Check if the form has been submitted (vs. displaying the initial
        # form) and if the data passed validation.  "submitted_and_valid"
        # is shorthand for "$form->submitted && !$form->has_errors"
        if ($form->submitted_and_valid) {
            # Create a new book
            my $book = $c->model('DB::Book')->new_result({});
            # Save the form data for the book
            $form->model->update($book);
            # 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")}));
            $c->detach;
        } else {
            # Get the authors from the DB
            my @author_objs = $c->model("DB::Author")->all();
            # Create an array of arrayrefs where each arrayref is an author
            my @authors;
            foreach (sort {$a->last_name cmp $b->last_name} @author_objs) {
                push(@authors, [$_->id, $_->last_name]);
            }
            # Get the select added by the config file
            my $select = $form->get_element({type => 'Select'});
            # Add the authors to it
            $select->options(\@authors);
        }
        # Set the template
        $c->stash(template => 'books/formfu_create.tt2');
    }

Create a Form Config File¶

Although HTML::FormFu supports any configuration file handled by Config::Any, most people tend to use YAML. First create a directory to hold your form configuration files:

    $ mkdir -p root/forms/books

Then create the file root/forms/books/formfu_create.yml and enter the following text:

    ---
    # indicator is the field that is used to test for form submission
    indicator: submit
    # Start listing the form elements
    elements:
        # The first element will be a text field for the title
        - type: Text
          name: title
          label: Title
          # This is an optional 'mouse over' title pop-up
          attributes:
            title: Enter a book title here
        # Another text field for the numeric rating
        - type: Text
          name: rating
          label: Rating
          attributes:
            title: Enter a rating between 1 and 5 here
        # Add a drop-down list for the author selection.  Note that we will
        # dynamically fill in all the authors from the controller but we
        # could manually set items in the drop-list by adding this YAML code:
        # options:
        #   - [ '1', 'Bastien' ]
        #   - [ '2', 'Nasseh'  ]
        - type: Select
          name: authors
          label: Author
        # The submit button
        - type: Submit
          name: submit
          value: Submit

NOTE: Copying and pasting YAML from Perl documentation is sometimes tricky. See the "Config::General Config for this tutorial" section of this document for a more foolproof config format.

Update the CSS¶

Edit root/static/css/main.css and add the following lines to the bottom of the file:

    ...
    input {
        display: block;
    }
    select {
        display: block;
    }
    .submit {
        padding-top: .5em;
        display: block;
    }

These changes will display form elements vertically.

Create a Template Page To Display The Form¶

Open root/src/books/formfu_create.tt2 in your editor and enter the following:

    [% META title = 'Create/Update Book' %]
    [%# Render the HTML::FormFu Form %]
    [% form %]
    <p><a href="[% c.uri_for(c.controller.action_for('list'))
        %]">Return to book list</a></p>

Add Links for Create and Update via "HTML::FormFu"¶

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

    ...
    <p>
      HTML::FormFu:
      <a href="[% c.uri_for(c.controller.action_for('formfu_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::FormFu-based form.

Test The HTML::FormFu Create Form¶

Make sure the server is running with the "-r" restart option:

    $ script/myapp_server.pl -r

Login as "test01" (password: mypass). Once at the Book List page, click the new HTML::FormFu "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.

Also note that this implementation allows you to create books with any bogus information. Although we have constrained the authors with the drop-down list (note that this isn't bulletproof because we still have not prevented a user from "hacking" the form to specify other values), there are no restrictions on items such as the length of the title (for example, you can create a one-letter title) and the value of the rating (you can use any number you want, and even non-numeric values with SQLite). The next section will address this concern.

Note: Depending on the database you are using and how you established the columns in your tables, the database could obviously provide various levels of "type enforcement" on your data. The key point being made in the previous paragraph is that the web application itself is not performing any validation.

Add Constraints¶

Open root/forms/books/formfu_create.yml in your editor and update it to match:

    ---
    # indicator is the field that is used to test for form submission
    indicator: submit
    # Start listing the form elements
    elements:
        # The first element will be a text field for the title
        - type: Text
          name: title
          label: Title
          # This is an optional 'mouse over' title pop-up
          attributes:
            title: Enter a book title here
          # Add constraints for the field
          constraints:
            # Force the length to be between 5 and 40 chars
            - type: Length
              min: 5
              max: 40
              # Override the default of 'Invalid input'
              message: Length must be between 5 and 40 characters
        # Another text field for the numeric rating
        - type: Text
          name: rating
          label: Rating
          attributes:
            title: Enter a rating between 1 and 5 here
          # Use Filter to clean up the input data
          # Could use 'NonNumeric' below, but since Filters apply *before*
          # constraints, it would conflict with the 'Integer' constraint below.
          # So let's skip this and just use the constraint.
          #filter:
            # Remove everything except digits
            #- NonNumeric
          # Add constraints to the field
          constraints:
            # Make sure it's a number
            - type: Integer
              message: "Required. Digits only, please."
            # Check the min & max values
            - type: Range
              min: 1
              max: 5
              message: "Must be between 1 and 5."
        # Add a select list for the author selection.  Note that we will
        # dynamically fill in all the authors from the controller but we
        # could manually set items in the select by adding this YAML code:
        # options:
        #   - [ '1', 'Bastien' ]
        #   - [ '2', 'Nasseh'  ]
        - type: Select
          name: authors
          label: Author
          # Convert the drop-down to a multi-select list
          multiple: 1
          # Display 3 entries (user can scroll to see others)
          size: 3
          # One could argue we don't need to do filters or constraints for
          # a select list, but it's smart to do validation and sanity
          # checks on this data in case a user "hacks" the input
          # Add constraints to the field
          constraints:
            # Make sure it's a number
            - Integer
        # The submit button
        - type: Submit
          name: submit
          value: Submit
    # Global filters and constraints.
    constraints:
        # The user cannot leave any fields blank
        - Required
        # If not all fields are required, move the Required constraint to the
        # fields that are
    filter:
        # Remove whitespace at both ends
        - TrimEdges
        # Escape HTML characters for safety
        - HTMLEscape

NOTE: Copying and pasting YAML from Perl documentation is sometimes tricky. See the "Config::General Config for this tutorial" section of this document for a more foolproof config format.

The main changes are:

• The "Select" element for "authors" is changed from a single-select drop-down to a multi-select list by adding configuration for the "multiple" and "size" options in formfu_create.yml.
• Constraints are added to provide validation of the user input. See HTML::FormFu::Constraint for other constraints that are available.
• A variety of filters are run on every field to remove and escape unwanted input. See HTML::FormFu::Filter for more filter options.

Try Out the Updated Form¶

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. When you click Submit, the HTML::FormFu "constraint" items will validate the logic and insert feedback as appropriate. Try adding blank spaces at the front or the back of the title and note that it will be removed.

Note that you can update your FormFu YAML forms and the development server does not need to reload -- the form definition is read from the YAML file each time a controller action uses it.

Try Out the Edit/Update Feature¶

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.

More Things to Try¶

You are now armed with enough knowledge to be dangerous. You can keep tweaking the example application; some things you might want to do:

• Add an appropriate authorization check to the new Edit function.
• Cleanup the List page so that the Login link only displays when the user isn't logged in and the Logout link only displays when a user is logged in.
• Add a more sensible policy for when and how users and admins can do things in the CRUD cycle.
• Support the CRUD cycle for authors.

Or you can proceed to write your own application, which is probably the real reason you worked through this Tutorial in the first place.

Config::General Config for this tutorial¶

If you are having difficulty with YAML config above, please save the below into the file formfu_create.conf and delete the formfu_create.yml file. The below is in Config::General format which follows the syntax of Apache config files.

    constraints   Required
    <elements>
        <constraints>
            min   5
            max   40
            type   Length
            message   Length must be between 5 and 40 characters
        </constraints>
        filter   TrimEdges
        filter   HTMLEscape
        name   title
        type   Text
        label   Title
        <attributes>
            title   Enter a book title here
        </attributes>
    </elements>
    <elements>
        constraints   Integer
        filter   TrimEdges
        filter   NonNumeric
        name   rating
        type   Text
        label   Rating
        <attributes>
            title   Enter a rating between 1 and 5 here
        </attributes>
    </elements>
    <elements>
        constraints   Integer
        filter   TrimEdges
        filter   HTMLEscape
        name   authors
        type   Select
        label   Author
        multiple   1
        size   3
    </elements>
    <elements>
        value   Submit
        name   submit
        type   Submit
    </elements>
    indicator   submit