RE: Possible Issue with DoubleField

[Shad Storhaug]

Hi Alexander,

Thanks for the report.

To answer your second question, Lucene's design has changed to accommodate a 
"LazyField" (in the Lucene.Net.Misc package) that is readonly. The return type 
of Document.GetField(string) is IIndexableField, not Field and therefore 
typically requires a cast in Java in order to use. To make this easier to work 
with in .NET, I have added a generic extension method overload so the cast is 
more obvious.

var field = doc.GetField<Field>(fieldName);

I am trying to avoid using something like public Field GetFieldAsField(), which 
would result in an exception in the rare case the underlying IIndexableField 
type could not be cast to a Field type, and it would not be so obvious that you 
have to call GetField(string) and cast to an alternative type.

You can try this approach out by copying the extension method into your 
project. 
https://github.com/apache/lucenenet/blob/master/src/Lucene.Net/Support/Document/DocumentExtensions.cs.
 


For the Single/Double field issue, thanks for putting together the code sample. 
It is a bit unclear from your question though - was this something that worked 
in 4.8.0.770-beta that quit working in 4.8.0-beta00004?


Thanks,
Shad Storhaug (NightOwl888)


-----Original Message-----
From: Roethinger, Alexander [mailto:aroethin...@affili.net] 
Sent: Friday, August 11, 2017 5:32 AM
To: dev@lucenenet.apache.org
Subject: Possible Issue with DoubleField

Dear Devs,

I just updated my search application from v4.8.0.770-beta to v4.8.0-beta00004.
It required some plausible code adjustments but otherwise worked just fine with 
all of my unit tests now passing.

I did notice something though with DoubleField (and possibly with SingleField 
as well, Int32Field and Int64Field both work fine) after extending my unit 
tests for some edge cases using  the MaxValues for those types.
Maybe I'm just missing something, but I thought I would raise it to the 
community and would appreciate your thoughts:

a) When storing a DoubleField with a value of double.MaxValue, the string 
representation of the field value is incorrect. Could it be that the Round-Trip 
Format Specifier "R" is missing?
b) When retrieving the same field, the FieldType properties of the retrieved 
field are not the same as when the field was stored.

This results in two challenges:
1) I can't use the Document.Get() method to retrieve the precise value. Instead 
I have to use GetNumericValue().
2) When examining the values of FieldType for the retrieved field, the 
properties do not match those of the stored field, ie. NumericType is set to 
NONE even though it should be DOUBLE or the value of IsTokenized is changed.
I'm not sure if this is expected behavior or not. I would have assumed that 
FieldType retrieves the values according to the way the field was originally 
created.
The problem with these two points is that I can't easily deduct how to properly 
retrieve the value based on the value of NumericType just  from reading the 
field.

Another point that confuses me:
Why do I need to explicitly cast FieldType to access the NumericType property 
instead of just  accessing the FieldType property of the Field? (see line 34: 
var fieldType = (FieldType)field.FieldType;)

The sample ConsoleApplication code below illustrates the behavior.

Any feedback is welcome!
And thanks for all the great work you have been doing!

Kind regards
Alexander

CODE:

using Lucene.Net.Analysis;
using Lucene.Net.Analysis.Standard;
using Lucene.Net.Documents;
using Lucene.Net.Index;
using Lucene.Net.Search;
using Lucene.Net.Store;
using Lucene.Net.Util;
using System;

namespace LuceneTest
{
    class Program
    {
        static void Main(string[] args)
        {
            Directory dir = new RAMDirectory();
            Analyzer analyzer = new StandardAnalyzer(LuceneVersion.LUCENE_48);
            IndexWriterConfig iwc = new 
IndexWriterConfig(LuceneVersion.LUCENE_48, analyzer);

            double value = double.MaxValue;
            string fieldName = "DoubleField";

            FieldType type = new FieldType();
            type.IsIndexed = true;
            type.IsStored = true;
            type.IsTokenized = false;
            type.NumericType = NumericType.DOUBLE;


            using (IndexWriter writer = new IndexWriter(dir, iwc))
            {
                Document doc = new Document();
                var field = new DoubleField(fieldName, value, type);
                var fieldType = (FieldType)field.FieldType;

                Console.WriteLine("DoubleField values for indexed value");
                Console.WriteLine("StringValue: {0}", field.GetStringValue());
                Console.WriteLine("NumericValue: {0:R}", 
field.GetNumericValue());
                Console.WriteLine("IsIndexed: {0}", fieldType.IsIndexed);
                Console.WriteLine("IsStored: {0}", fieldType.IsStored);
                Console.WriteLine("IsTokenized: {0}", fieldType.IsTokenized);
                Console.WriteLine("Numreric: {0}", fieldType.NumericType);

                doc.Add(field);
                writer.AddDocument(doc);
                writer.Commit();
            }

            Console.WriteLine();

            using (IndexReader reader = DirectoryReader.Open(dir))
            {
                IndexSearcher searcher = new IndexSearcher(reader);
                var hits = searcher.Search(new MatchAllDocsQuery(), 
10).ScoreDocs;

                Document doc = searcher.Doc(hits[0].Doc);
                var field = doc.GetField(fieldName);
                var fieldType = (FieldType)field.FieldType;

                Console.WriteLine("DoubleField values for searched value");
                Console.WriteLine("StringValue: {0}", field.GetStringValue());
                Console.WriteLine("NumericValue: {0:R}", 
field.GetNumericValue());
                Console.WriteLine("IsIndexed: {0}", fieldType.IsIndexed);
                Console.WriteLine("IsStored: {0}", fieldType.IsStored);
                Console.WriteLine("IsTokenized: {0}", fieldType.IsTokenized);
                Console.WriteLine("Numreric: {0}", fieldType.NumericType);

            }

            Console.ReadKey();

            dir.Dispose();
        }

    }
}