Lucene.NET & Facete Search Solution

Question

Hey just started using Lucene.NET, any was wondering if anyone had a working example of Lucene.NET with a faceted search.

I know this below link http://www.devatwork.nl/articles/lucenenet/faceted-search-and-drill-down-lucenenet/

Which looked great, but all it does is tell me the number of results in the faceted search but not actually how I can retrieve the index and details of those results. ie as in a normal search in Lucene.NET.

Ie from that link he has the following snippet

    private static void FacetedSearch(string indexPath, string genre, string term){
var searcher = new IndexSearcher(indexPath);
// first get the BitArray result from the genre query
var genreQuery = new TermQuery(new Term("genre", genre));
var genreQueryFilter = new QueryFilter(genreQuery);
BitArray genreBitArray = genreQueryFilter.Bits(searcher.GetIndexReader());
Console.WriteLine("There are " + GetCardinality(genreBitArray) + " document with the genre " + genre);

// Next perform a regular search and get its BitArray result
Query searchQuery = MultiFieldQueryParser.Parse(term, new[] {"title", "description"}, new[] {BooleanClause.Occur.SHOULD, BooleanClause.Occur.SHOULD}, new StandardAnalyzer());
var searchQueryFilter = new QueryFilter(searchQuery);
BitArray searchBitArray = searchQueryFilter.Bits(searcher.GetIndexReader());
Console.WriteLine("There are " + GetCardinality(searchBitArray) + " document containing the term " + term);

// Now do the faceted search magic, combine the two bit arrays using a binary AND operation
BitArray combinedResults = searchBitArray.And(genreBitArray);
Console.WriteLine("There are " + GetCardinality(combinedResults) + " document containing the term " + term + " and which are in the genre " + genre);
}

Which will tell me ie there is 2 records for the search term "Dublin" and which are in genre "Financial" which is perfect but the article seems to skip the part where it says how I can retrieve the indexes of those results and display on screen.

He does explain this in the link below for a normal search but not facete search..

ie Normal Search

    private static void Search(string indexPath, string term)
{
// create searcher
var searcher = new IndexSearcher(indexPath);

// create a query which searches through the title and description, the term can be in the title or the description
Query searchQuery = MultiFieldQueryParser.Parse(term, new[] {"title", "description"}, new[] {BooleanClause.Occur.SHOULD, BooleanClause.Occur.SHOULD}, new StandardAnalyzer());

// perform the search
Hits hits = searcher.Search(searchQuery);

// loop through all the hits and show their title
for (int hitIndex = 0; hitIndex < hits.Length(); hitIndex++)
{
// get the corresponding document
Document hitDocument = hits.Doc(hitIndex);

// write its title to the console
Console.WriteLine(hitDocument.GetField("title").StringValue());
}
}

http://www.devatwork.nl/articles/lucenenet/search-basics-lucenenet/

Any help would be greatly appreciated

Edit :

Or should I do a search query and then do a Filter on the results ?

Answer 1

The BitArray represents hits. Each 1 has an index, that is equal to document id

So 1001001 means that documents with position 0, 3 and 6 in index match your search. You just have to retrieve them from lucene index.

var searcher = new IndexSearcher(indexPath);

// get document at position 0
var doc = searcher.Doc( 0 );