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Catalyst::Manual::TutCatalyst::Manual::Tutorial::09_AdvancedCRUD::09_FormFu(3)

NAME
       Catalyst::Manual::Tutorial::09_AdvancedCRUD::09_FormFu - Catalyst
       Tutorial - Chapter 9: Advanced CRUD - FormFu

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_FormFu

       10. Appendices

DESCRIPTION
       This portion of the tutorial explores HTML::FormFu and how it can be
       used to manage forms, perform validation of form input, as well as save
       and restore data to/from the database.

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

       Source code for the tutorial in included in the /home/catalyst/Final
       directory of the Tutorial Virtual machine (one subdirectory per
       chapter).  There are also instructions for downloading the code in
       Catalyst::Manual::Tutorial::01_Intro.

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

   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 '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.

HTML::FormFu VALIDATION AND FILTERING
       Although the use of HTML::FormFu in the previous section did provide an
       automated mechanism to build the form, the real power of this module
       stems from functionality that can automatically validate and filter the
       user input.  Validation uses constraints to be sure that users input
       appropriate data (for example, that the email field of a form contains
       a valid email address).	Filtering can also be used to remove
       extraneous whitespace from fields or to escape meta-characters in user
       input.

   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.

CREATE AND UPDATE/EDIT ACTION
       Let's expand the work done above to add an edit action.	First, open
       "lib/MyApp/Controller/Books.pm" and add the following method to the
       bottom:

	   =head2 formfu_edit

	   Use HTML::FormFu to update an existing book

	   =cut

	   sub formfu_edit :Chained('object') :PathPart('formfu_edit') :Args(0)
		   :FormConfig('books/formfu_create.yml') {
	       my ($self, $c) = @_;

	       # Get the specified book already saved by the 'object' method
	       my $book = $c->stash->{object};

	       # Make sure we were able to get a book
	       unless ($book) {
		   # Set an error message for the user & return to books list
		   $c->response->redirect($c->uri_for($self->action_for('list'),
		       {mid => $c->set_error_msg("Invalid book -- Cannot edit")}));
		   $c->detach;
	       }

	       # 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) {
		   # Save the form data for the book
		   $form->model->update($book);
		   # Set a status message for the user
		   # 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 edited")}));
		   $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);
		   # Populate the form with existing values from DB
		   $form->model->default_values($book);
	       }

	       # Set the template
	       $c->stash(template => 'books/formfu_create.tt2');
	   }

       Most of this code should look familiar to what we used in the
       "formfu_create" method (in fact, we should probably centralize some of
       the common code in separate methods).  The main differences are:

       ·   We have to manually specify the name of the FormFu .yml file as an
	   argument to ":FormConfig" because the name can no longer be
	   automatically deduced from the name of our action/method (by
	   default, FormFu would look for a file named
	   "books/formfu_edit.yml").

       ·   We load the book object from the stash (found using the $id passed
	   to the Chained object method)

       ·   We use $id to look up the existing book from the database.

       ·   We make sure the book lookup returned a valid book.	If not, we set
	   the error message and return to the book list.

       ·   If the form has been submitted and passes validation, we skip
	   creating a new book and just use "$form->model->update" to update
	   the existing book.

       ·   If the form is being displayed for the first time (or has failed
	   validation and it being redisplayed), we use
	   "$form->model->default_values" to populate the form with data from
	   the database.

       Then, edit "root/src/books/list.tt2" and add a new link below the
       existing "Delete" link that allows us to edit/update each existing
       book.  The last <td> cell in the book list table should look like the
       following:

	   ...
	   <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('formfu_edit'), [book.id]) %]">Edit</a>
	   </td>
	   ...

       Note: Only add three lines (the "Add a link to edit a book" comment and
       the href for "formfu_edit").  Make sure you add it below the existing
       "delete" link.

   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

AUTHOR
       Kennedy Clark, "hkclark@gmail.com"

       Feel free to contact the author for any errors or suggestions, but the
       best way to report issues is via the CPAN RT Bug system at
       https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual
       <https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.

       Copyright 2006-2011, Kennedy Clark, under the Creative Commons
       Attribution Share-Alike License Version 3.0
       (http://creativecommons.org/licenses/by-sa/3.0/us/
       <http://creativecommons.org/licenses/by-sa/3.0/us/>).

perl v5.14.2	     Catalyst::Manual::Tutorial::09_AdvancedCRUD::09_FormFu(3)
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