[Catalyst] "Best Practice" for validating form input

I'm new too all this, too. Here's what I'm doing in one controller --
I'll post in hopes someone can point out what I could do better.. ;)

This is in a general CRUD controller.


sub update_record : Private {
my ( $self, $c ) = @_;

my $form = $c->form(
optional => [ qw/ optional / ],
required => [ qw/ name foo bar active / ],
constraints => {
active => qr/(?:0|1)/,
},
missing_optional_valid => 1, # see Data::FormValidator
);

if ( $form->has_missing || $form->has_invalid ) {
$c->stash->{message} = 'Fix the form, will ya!';
$c->stash->{errors} = $form->msgs;
return $c->forward('edit');
}

# "item" was loaded a previous action.

if ( $c->stash->{item} ) {
$c->stash->{item}->update_from_form( $c->form );
} else {
$c->stash->{class}->create_from_form( $c->form );
}

# redisplay the list of items
$c->forward('list');
}

I'm using Catalyst::Plugin::FormValidator and ::FillInForm which does
a bit of the magic. Namely, it calls FillInForm automatically when it
seems $form->has_missing or $form->has_invalid.

[snip]

Hi Bill,

Thanks for the example above. I am implementing this too, and was
wondering if you have any code showing how you display $form->msgs. I
see they are a hash of <span> tags, but wondering if there was another
option in displaying them other than just looping through the hash and
printing the <span>'s.

Specifically, I'd like to have the <span> placed beside the field that
had the problem. One thing I thought about is using some JS to add
the <span> after the element with the error.

The only thing is I'm dealing with a "conditional" form. By that I
mean that I have 20 questions/form elements over all and rather than
coding a multi-page form, I have some JavaScript that displays the
appropriate question, based on that question, the next, and so on.
So, I might just need to display the <span>'s at the top of the page.

Either way, I'd like to know if you (or anyone on the list) has the
<span>'s displaying next to the field with the error.

Any help is greatly appreciated,
Kevin

We turn them into keys to be used to retrieve messages from a
Class::Phrasebook file.

This is some code to change a D::FV error about an invalid first_name
field into the string first_name_invalid:

sub _errs_to_messages {
my ($self, $errs) = @_;

foreach my $field_name ( sort keys %{$errs} ) {
# decode error type from value set
my $value = $errs->{$field_name};
my $error_type;
if ($value =~ /missing/i) {
$error_type = 'missing';
} elsif ($value =~ /invalid/i) {
$error_type = 'invalid';
} else {
croak("Unknown error type for field '$field_name' value
'$value'");
}

# add a message for the error
add_message("${field_name}_$error_type", from_module => ref
($self));
}
}
For this, we use background colors to highlight the invalid or missing
fields. For example:
<input name="first_name" type="text" value="" style="width:
200px;<tmpl_if err_first_name> background-color: #ffe66b;</tmpl_if>" />

(We set err_${field_name} for each of the D::FV errors.)
You should be able to get your template to do that.

- Perrin

On 8/25/05, Perrin Harkins wrote:
[snip]
Perrin,

Thanks for the example code. Any idea if HTML::Mason has an
equivalent of HTML::Template's <tmpl_if>? I'm trying to avoid a huge
<%perl> block with an if statement in each <input>.


Thanks for your help,
Kevin

<% (condition) ? 'true value to print' : 'false value to print' %>

Or this:

% if (condition) {
background-color: #ffe66b;
% }

- Perrin

Thanks everyone!

One small example of a pattern is shown in the ServerDB example.
(see Catalyst Wiki catalyst.perl.org front page, section Examples,
which links to http://www.hybridized.org/catalyst/)

If you look in the source for its ServerDB::C::Server controller,
you will see two actions, 'view' and 'do_edit'. 'view' is used to
display the form (template at root/server/view.xhtml). The form
references the submit action 'do_edit'. 'do_edit' has the code
which _could_ do the validation of form values. If there were
errors it could just as easily do what it already does after
processing correct values, just forward (not redirect) to action
'view' to redisplay the form:
$c->forward('view', join "/", @name);

If you will notice in some of the other examples and documentation,
including the plugin FillInForm in the application class
use Catalyst qw{ -Debug FillInForm ... };
means that forms easily and automatically (and spookily) have the
prior form fields value filled in. That is, just redisplaying the
form will show the problem values!

So anyway, with the forward() capability, it is easy to have one
action that displays forms, and another that validates values
submitted. If there is an error, just forward to the display
action and return from the submit action. At least, that's _my_ theory. ;)