How to do case insensitive sorting of Norwegian characters (Æ, Ø, and Å) using Hibernate Lucene Search?

Question

æ, ø, å are latest letters in the norwegian alphabet

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Æ Ø Å

When we try to sort it usin

Answer 1

You can use org.apache.lucene.collation.CollationKeyFilter class in Hibernate Search version 4.3.0.Final. Create your own collation filter factory:

import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.collation.CollationKeyFilter;
import org.apache.solr.analysis.BaseTokenFilterFactory;

import java.text.Collator;
import java.util.Locale;

public final class NorwegianCollationFactory extends BaseTokenFilterFactory {

    @Override
    public TokenStream create(TokenStream input) {
        Collator norwegianCollator = Collator.getInstance(new Locale("no", "NO"));
        return new CollationKeyFilter(input, norwegianCollator);
    }

}

And the use this collation factory in your AnalyzerDef:

@AnalyzerDef(name = "myOwnAnalyzer",
tokenizer = @TokenizerDef(factory = KeywordTokenizerFactory.class),
filters = {
    @TokenFilterDef(factory = ASCIIFoldingFilterFactory.class),
    @TokenFilterDef(factory = LowerCaseFilterFactory.class),
    @TokenFilterDef(factory = PatternReplaceFilterFactory.class, params = {
        @Parameter(name = "pattern", value = "('-&\\.,\\(\\))"),
        @Parameter(name = "replacement", value = " "),
        @Parameter(name = "replace", value = "all")
    }),
    @TokenFilterDef(factory = PatternReplaceFilterFactory.class, params = {
        @Parameter(name = "pattern", value = "([^0-9\\p{L} ])"),
        @Parameter(name = "replacement", value = ""),
        @Parameter(name = "replace", value = "all")
    }),
    @TokenFilterDef(factory = TrimFilterFactory.class)
,
    @TokenFilterDef(factory = NorwegianCollationFactory .class)
}
)
public class KikaPaya implements Serializable {

More information about using this Collation filter with hibernate search version 5 - https://stackoverflow.com/a/60738067/7179509