On 1/9/12 2:25 PM, Jason McIntosh wrote:
Howdy Lucy-users,
My client requires the ability to search for blank fields. In other
words, they'd like to construct search queries that parse as e.g.
"Show me all results with the title 'MyTitle' but no description",
and this would return as hits all items whose "title" field contains
"MyTitle", and whose "description" field is completely blank.
These sort of null-searches don't appear to be an out-of-the-box
feature of Lucy's default query parser; a naive query like
"title:MyTitle AND description:" doesn't work as I hope. So it looks
like I will have to knit some custom magic here, or perhaps use an
extension module. I write this list in the hope for some introductory
pointers; I'm a little unsure where to start, or whether this is a
solved problem and I'm not finding it.
I use Search::Query::Dialect::Lucy[0] to do this, in conjunction with
this kind of query mangling:
my $query_str = get_user_input();
# syntactic sugar for finding empty fields
$query_str =~ s/(\w+)\s*[:=]\s*NULL/$1!=?*/g;
$query_str =~ s/(\w+)\s*\![:=]\s*NULL/$1=?*/g;
# turn string into a Lucy query
my $query = Search::Query->parser( dialect => 'Lucy' )
->parse($query_str);
my $lucy_query = $query->as_lucy_query();
my $hits = $lucy_searcher->hits( query => $lucy_query );
So you can search for:
description=NULL and title=MyTitle
and get what you're after.
[0] https://metacpan.org/module/Search::Query::Dialect::Lucy
--
Peter Karman . http://peknet.com/ . [email protected]
