$external_structure = {
	'name' => 'Test product',
	'id' => 'ABC123',
	'data' => {
				 'enabled' => '1',
				 'internal_id' => '',
				 'urls' => {
							  'main_url' => ''
							},
				 'price' => '1000',
				 'unit' => 'ST',
				 'unit_info' => {
								   'qty' => '1',
								   'gtin' => '1234567890'
								 }
			   }
        };

##</code><code>##

my $internal_structure = {};

$internal_structure->{'product_id'} = $external_structure->{'id'};
$internal_structure->{'price_excl_vat'} = $external_structure->{'data'}->{'price'};
$internal_structure->{'qty'} = $external_structure->{'data'}->{'unit_info'}->{'qty'};
# etc...


##</code><code>##

product_id;id
price_excl_vat;data#price
qty;data#unit_info#qty