Lucene.NET "OR"

Question

How do I do an "OR" in Lucene.NET. Basically what I have is an array of IDs and I want to return any records where a particular field contains any of the values. I previously was doing this with just one value, but now I want to convert the following code so that MetaDataID is an array of possible values instead of one single value.

if (MetaDataID.Length > 0)
    completeQuery.Add(new QueryParser("MetaData", new StandardAnalyzer()).Parse(MetaDataID), BooleanClause.Occur.MUST);

Answer 1

When combining Lucene queries where you want any index record that contains any one of multiple possible values with additional criteria that must also be met, create multiple boolean query objects.

For the first group of "OR" conditions:

BooleanQuery booleanQueryInner = new BooleanQuery();
Query query1 = new TermQuery(new Term("id", "<id 1>"));
Query query2 = new TermQuery(new Term("id", "<id 2>"));
Query query3 = new TermQuery(new Term("id", "<id 3>"));
Query query4 = new TermQuery(new Term("id", "<id 4>"));
booleanQueryInner.add(query1, BooleanClause.Occur.SHOULD);
booleanQueryInner.add(query2, BooleanClause.Occur.SHOULD);
booleanQueryInner.add(query3, BooleanClause.Occur.SHOULD);
booleanQueryInner.add(query4, BooleanClause.Occur.SHOULD);

Now combine with other conditions in query

BooleanQuery booleanQueryOuter = new BooleanQuery();
booleanQueryOuter.add(booleanQueryInner, BooleanClause.Occur.MUST);
booleanQueryOuter.add(boolenaQueryOtherConditions, BooleanClause.Occur.MUST);

Now index records will only be returned if they meet one of the conditions in the inner "OR" group and also meet the conditions in the "other conditions" query.