Lucene.Net: How can I add a date filter to my search results?
- by rockinthesixstring
I've got my searcher working really well, however it does tend to return results that are obsolete. My site is much like NerdDinner whereby events in the past become irrelevant.
I'm currently indexing like this
Public Function AddIndex(ByVal searchableEvent As [Event]) As Boolean Implements ILuceneService.AddIndex
Dim writer As New IndexWriter(luceneDirectory, New StandardAnalyzer(), False)
Dim doc As Document = New Document
doc.Add(New Field("id", searchableEvent.ID, Field.Store.YES, Field.Index.UN_TOKENIZED))
doc.Add(New Field("fullText", FullTextBuilder(searchableEvent), Field.Store.YES, Field.Index.TOKENIZED))
doc.Add(New Field("user", If(searchableEvent.User.UserName = Nothing,
"User" & searchableEvent.User.ID,
searchableEvent.User.UserName),
Field.Store.YES,
Field.Index.TOKENIZED))
doc.Add(New Field("title", searchableEvent.Title, Field.Store.YES, Field.Index.TOKENIZED))
doc.Add(New Field("location", searchableEvent.Location.Name, Field.Store.YES, Field.Index.TOKENIZED))
doc.Add(New Field("date", searchableEvent.EventDate, Field.Store.YES, Field.Index.UN_TOKENIZED))
writer.AddDocument(doc)
writer.Optimize()
writer.Close()
Return True
End Function
Notice how I have a "date" index that stores the event date.
My search then looks like this
''# code omitted
Dim reader As IndexReader = IndexReader.Open(luceneDirectory)
Dim searcher As IndexSearcher = New IndexSearcher(reader)
Dim parser As QueryParser = New QueryParser("fullText", New StandardAnalyzer())
Dim query As Query = parser.Parse(q.ToLower)
''# We're using 10,000 as the maximum number of results to return
''# because I have a feeling that we'll never reach that full amount
''# anyways. And if we do, who in their right mind is going to page
''# through all of the results?
Dim topDocs As TopDocs = searcher.Search(query, Nothing, 10000)
Dim doc As Document = Nothing
''# loop through the topDocs and grab the appropriate 10 results based
''# on the submitted page number
While i <= last AndAlso i < topDocs.totalHits
doc = searcher.Doc(topDocs.scoreDocs(i).doc)
IDList.Add(doc.[Get]("id"))
i += 1
End While
''# code omitted
I did try the following, but it was to no avail (threw a NullReferenceException).
While i <= last AndAlso i < topDocs.totalHits
If Date.Parse(doc.[Get]("date")) >= Date.Today Then
doc = searcher.Doc(topDocs.scoreDocs(i).doc)
IDList.Add(doc.[Get]("id"))
i += 1
End If
End While
I also found the following documentation, but I can't make heads or tails of it
http://lucene.apache.org/java/1_4_3/api/org/apache/lucene/search/DateFilter.html
