private string GetFieldFromExtractTerms(Query query)
{
ISet <Term> terms = new HashSet <Term>();
try
{
_searcher.createNormalizedWeight(query, false).extractTerms(terms);
}
catch (IOException ioe)
{
throw new System.NotSupportedException(ioe);
}
catch (System.NotSupportedException)
{
// TODO This is for "*" queries and such. Lucene doesn't seem
// to be able/willing to rewrite such queries.
// Just ignore the orphans then... OK?
}
return(terms.Count == 0 ? null : terms.GetEnumerator().next().field());
}