Searching for text stored with accents in Lucene.NET

ASCIIFoldingAnalyzer.cs

using System;
using System.IO;
using Lucene.Net.Analysis;
using Lucene.Net.Analysis.Standard;
using Lucene.Net.Documents;
using Lucene.Net.Index;
using Lucene.Net.QueryParsers;
using Lucene.Net.Search;
using Lucene.Net.Store;
using NUnit.Framework;
using Version = Lucene.Net.Util.Version;

public class ASCIIFoldingAnalyzer : Analyzer
{
    private readonly Analyzer subAnalyzer;

    public ASCIIFoldingAnalyzer(Analyzer subAnalyzer)
    {
        this.subAnalyzer = subAnalyzer;
    }

    public override TokenStream TokenStream(string fieldName, TextReader reader)
    {
        var result = subAnalyzer.TokenStream(fieldName, reader);
        result = new ASCIIFoldingFilter(result);
        return result;
    }
}

[TestFixture]
public class can_search_for_accent_stored_text_with_accented_and_non_accented_query
{
    private string accentQueryFieldValue;
    private string nonAccentQueryFieldValue;

    [TestFixtureSetUp]
    public void TestFixtureSetUp()
    {
        var path = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString());
        var directory = new SimpleFSDirectory(new DirectoryInfo(path));

        var analyzer = new ASCIIFoldingAnalyzer(new StandardAnalyzer(Version.LUCENE_29));

        var doc = new Document();
        doc.Add(new Field("afield", "jóhn", Field.Store.YES, Field.Index.ANALYZED));

        using (var indexWriter = new IndexWriter(directory, analyzer, true, IndexWriter.MaxFieldLength.UNLIMITED))
        {
            indexWriter.AddDocument(doc);
        }

        using (var indexReader = IndexReader.Open(directory, true))
        {
            using (var indexSearcher = new IndexSearcher(indexReader))
            {
                var queryParser = new QueryParser(Version.LUCENE_29, "afield", analyzer);

                accentQueryFieldValue = GetFieldValue("jóhn", queryParser, indexSearcher, default(Filter), indexReader);
                nonAccentQueryFieldValue = GetFieldValue("john", queryParser, indexSearcher, default(Filter), indexReader);
            }
        }
    }

    private static string GetFieldValue(string queryText, QueryParser queryParser, IndexSearcher indexSearcher, Filter filter, IndexReader indexReader)
    {
        var query = queryParser.Parse(queryText);
        var topDocs = indexSearcher.Search(query, filter, 1000);
        var fieldValue = default(string);
        if (topDocs.TotalHits == 1)
        {
            var scoreDoc = topDocs.ScoreDocs[0];
            var document = indexReader.Document(scoreDoc.doc);
            fieldValue = document.Get("afield");
        }
        return fieldValue;
    }

    [Test]
    public void accent_query_field_value_has_accent()
    {
        Assert.AreEqual("jóhn", accentQueryFieldValue);
    }

    [Test]
    public void non_accent_query_field_value_has_accent()
    {
        Assert.AreEqual("jóhn", nonAccentQueryFieldValue);
    }
}

How ASCIIFoldingAnalyzer would be in Lucene.Net 4.8?

@jesuslpm any luck? Tried to add this class but seems out dated for some methods that no longer exist in parent class.

Sorry, this is very old code - wouldn't know how to update it for modern libraries.

@diegolaz https://gist.github.com/jesuslpm/1d61e903b5efc379cbb09461e55d5e65

Yes sorry, updated with a custom analyzer and its working fine. Thanks for the answers!