I've recently upgraded to Solr 1.3 using Lucene 2.4. One of the reasons I upgraded was because of the nicer SearchComponent architecture that let me add a needed feature to the default request handler. Simply put, I needed to filter a query based on some additional parameters. So I subclassed QueryComponent and replaced the line
rb.setQuery( parser.getQuery() ); with one that wrapped the parsed query in a FilteredQuery Query query = parser.getQuery(); String arguments = params.get("param-name"); if( arguments != null) { query = new FilteredQuery(query, new MyCustomFilter(arguments)); } rb.setQuery(query); The filter class I used can be seen here: http://privatepaste.com/021ZH27tKG. And is nearly verbatim from the Lucene in Action book, when describing a way to do security filtering. This seems to work fine, although I'm getting some strange behavior when exercising this code through some unit tests from my Rails app. Sometimes I get an NPE when doing the filtering. at top level in at org.apache.lucene.index.MultiSegmentReader$MultiTermDocs.doc(MultiSegmentReader.java at line 533 at <MyQueryComponent>$MyCustomFilter.bits(Unknown Source) at top level in at org.apache.lucene.search.Filter.getDocIdSet(Filter.java at line 49 at top level in at org.apache.lucene.search.FilteredQuery$1.scorer(FilteredQuery.java at line 105 at top level in at org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java at line 132 at top level in at org.apache.lucene.search.Searcher.search(Searcher.java at line 126 After some detective work I decided the problem had to do with an empty index, and the termDocs iterator has 0 elements to iterate over and was throwing this error. Since there is no size() method or analogous method on the TermDocs iterator, I decided to use docFreq(term) as you can see in the source code. But this didn't solve my problem either. This error is being throw even when docFreq(term) returns more then 0 documents. I can't for the life of me figure out why this iterator's doc() method throwing an NPE. (Well I can deduce that the current member is null, but I don't know why.) Is the index corrupted? I can see record in the index that should match my Term through the solr /admin/ interface, and docFreq(term) returns a number > 0. Yet this NPE keeps showing up. Any help or guidance would be appreciated. If you need to see more source I'd be happy to provide it, but I'm sure thats all the relevant stuff. (I cross posted this to both Solr and Lucene lists.) Comron