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

I adapted Jeremies answer for C# and Lucene.Net 3.0.3. I also needed type double instead of int. This is my code:

using System.Globalization;
using Lucene.Net.Analysis;
using Lucene.Net.Index;
using Lucene.Net.QueryParsers;
using Lucene.Net.Search;
using Lucene.Net.Util;
using Version = Lucene.Net.Util.Version;

namespace SearchServer.SearchEngine
{
    internal class SearchQueryParser : QueryParser
    {
        public SearchQueryParser(Analyzer analyzer)
            : base(Version.LUCENE_30, null, analyzer)
        {
        }

        private const NumberStyles DblNumberStyles = NumberStyles.AllowLeadingWhite | NumberStyles.AllowTrailingWhite | NumberStyles.AllowLeadingSign | NumberStyles.AllowDecimalPoint;

        protected override Query NewRangeQuery(string field, string part1, string part2, bool inclusive)
        {
            if (field == "p")
            {
                double part1Dbl;
                if (!double.TryParse(part1, DblNumberStyles, CultureInfo.InvariantCulture, out part1Dbl))
                    throw new ParseException($"Error parsing value {part1} for field {field} as double.");
                double part2Dbl;
                if (!double.TryParse(part2, DblNumberStyles, CultureInfo.InvariantCulture, out part2Dbl))
                    throw new ParseException($"Error parsing value {part2} for field {field} as double.");
                return NumericRangeQuery.NewDoubleRange(field, part1Dbl, part2Dbl, inclusive, inclusive);
            }
            return base.NewRangeQuery(field, part1, part2, inclusive);
        }

        protected override Query NewTermQuery(Term term)
        {
            if (term.Field == "p")
            {
                double dblParsed;
                if (!double.TryParse(term.Text, DblNumberStyles, CultureInfo.InvariantCulture, out dblParsed))
                    throw new ParseException($"Error parsing value {term.Text} for field {term.Field} as double.");
                return new TermQuery(new Term(term.Field, NumericUtils.DoubleToPrefixCoded(dblParsed)));
            }
            return base.NewTermQuery(term);
        }
    }
}

I improved my code to also allow queries like greater than and lower than when an asterisk is passed. E.g. p:[* TO 5]

...
    double? part1Dbl = null;
    double tmpDbl;
    if (part1 != "*")
    {
        if (!double.TryParse(part1, DblNumberStyles, CultureInfo.InvariantCulture, out tmpDbl))
            throw new ParseException($"Error parsing value {part1} for field {field} as double.");
        part1Dbl = tmpDbl;
    }
    double? part2Dbl = null;
    if (part2 != "*")
    {
        if (!double.TryParse(part2, DblNumberStyles, CultureInfo.InvariantCulture, out tmpDbl))
            throw new ParseException($"Error parsing value {part2} for field {field} as double.");
        part2Dbl = tmpDbl;
    }
    return NumericRangeQuery.NewDoubleRange(field, part1Dbl, part2Dbl, inclusive, inclusive);
...