be careful

my @a = ( 'a', $c->req->param('a'), 'b', $c->req->param('b'), 'c', undef , 'd',, 'f' );$c->res->body(Dumper(\@a));

when we try "?b=1", output:

$VAR1 = [
          'a',
          'b',
          '1',
          'c',
          undef,
          'd',
          'f'
        ];

see? $c->req->param('a') is NOT undef.
so when u try something like

$rs->update( {
    column1 => $c->req->param('column1'),
    column2 => $c->req->param('column2')
} );

then if column1 param is not specified, this would raise error because $rs try to update column1, column2, $c->req->param('column2'). we want 4 but u give me 3.

so man, be careful of that. :)