How do I make the QueryParser in Lucene handle numeric ranges?

Question

new QueryParser(.... ).parse (somequery);

it works only for string indexed fields. Say i have a field called count where count is a integer field (

Answer 1

In Lucene 6, the protected method QueryParser#getRangeQuery still exists with the argument list (String fieldName, String low, String high, boolean startInclusive, boolean endInclusive), and overriding it to interpret the range as a numeric range is indeed possible, as long as that information is indexed using one of the new Point fields.

When indexing your field:

document.add(new FloatPoint("_point_count", value)); // index for efficient range based retrieval
document.add(new StoredField("count", value)); // if you need to store the value itself

At your custom query parser (extending queryparser.classic.QueryParser), override the method with something like this:

@Override
protected Query getRangeQuery(String field, String low, String high, boolean startInclusive, boolean endInclusive) throws ParseException
{
    if («isNumericField»(field)) // context dependent
    {
        final String pointField = "_point_" + field;
        return FloatPoint.newRangeQuery(pointField,
                Float.parseFloat(low),
                Float.parseFloat(high));
    }

    return super.getRangeQuery(field, low, high, startInclusive, endInclusive);
}