[Dbix-class] Filtering module

[jackal]

On Thursday 23 October 2008 20:18:49 Jess Robinson wrote:
> On Tue, 21 Oct 2008, jackal wrote:
> > This is proposal for a filtering component, similar to
> > DBIx::Class::InflateColumn
> > It can -modify- columns transparently. When you read column - it
> > inflates, when you write - deflates.
> > On creating a new column, whole cycle passed - deflating for DB and
> > inflating for usage.
> > Module can handle scalars, because of it's destination - to modify data.
>
> I think I see where you are going, but can you give some actual examples
> with data, how to use it etc?
>
> Someone did start/implement a ::Filter module, but I'm not sure where that
> went or why it disappeared.. That one was *just* for scalar to scalar
> though.

One example is in a module documentation:

package DB::Test;
use String::Util ':all';
__PACKAGE__->modify_column('html', {
    inflate => sub { htmlesc(shift) }, # escaping html entities
    deflate => sub { crunch(shift); }  # removing extra whitespaces
});

in a script:
$r = $schema->resultset('Test')->create({html => ' a  & b '}); # it will be 
deflated into DB as 'a & b'
$r->html; # inflated as 'a & b'
$r->html(' c & d '); # deflated into DB as 'c & d'
$r->update;
$r->html; # inflated as 'c & b'

Here you must send data without html entities, but if you use data in your 
html templates only and you don't want to modify data in controllers - you 
shouldn't worry about this, because browsers will decode html entities by 
themselves.


There's another example:

package DB::Test;
use String::Util ':all';
__PACKAGE__->modify_column('homepage', {
    inflate => sub { $_[0] }, # as is
    deflate => sub {
        my $value = trim(shift);
        if ($value !~ m!^([a-z]+://)?[a-z0-9\-\.]+([\/\?].*)?$!si) {
            $value = undef;
        } else {
            $value .= '/' if ($value =~ m!^([a-z]+://)?[a-z0-9\-\.]+$!si);
            $value = 'http://'.$value if ($value !~ m!^[a-z]+://!si);
        }
        return $value;
    }
});

in a script:
$r = $schema->resultset('Test')->create({homepage => ' site.ru '}); # it will 
be deflated into DB as 'http://site.ru/'
$r->homepage; # inflated as 'http://site.ru/' (as is)
$r->homepage('ftp://site.ru '); # deflated into DB as 'ftp://site.ru/'
$r->update;
$r->homepage; # inflated as 'ftp://site.ru/' (as is)

>
> > Module can works together with InflateColumn:
> > __PACKAGE__->modify_column('passw', ...);
> > __PACKAGE__->inflate_column('passw', ...);
> >
> > In that case, when you read - it inflates into object by InflateColumn,
> > then object will be modified by ModifyColumn. When wou write - there's
> > reverse process.
>
> Again, examples? ;)

There's example of using module with InflateColumn:

package DB::Test;
use URI;
__PACKAGE__->inflate_column('homepage', {
    inflate => sub { URI->new($_[0]) },
    deflate => sub { shift->as_string }
});
__PACKAGE__->modify_column('homepage', {
    inflate => sub { $_[0] }, # as is
    deflate => sub { shift->canonical } # normalize
});

in a script:

# it will be deflated into canonical version by ModifyColumn, then deflated 
into scalar by InflateColumn
$r = $schema->resultset('Test')->create({homepage => 
URI->new('HTTP://WWW.perl.com:80')}); # deflated into DB 
as 'http://www.perl.com/'

# it will be inflated into URI object by InflateColumn, then it can be 
modified by ModifyColumn (vice-versa)
$r->homepage->as_string; # inflated as 'http://www.perl.com/' (as is)

>
> Jess


-- 
Kind regards, Eugeny.