How to store java enums using spring-data-elasticsearch

Question

public enum Smoking {
    NO("No"),YES("Yes");
}

How to store java enums using spring-data-elasticsearch, I want to store Yes, No and search for the same

Answer 1

You can do so by providing custom converters for your Enum to convert it from and to a String. I suppose you want to have this property as a keyword in Elasticsearch and not analyzed.

Here is an implementation of the Smoking enum where I have added the necessary converters as nested enums (I prefer to use the enum as singleton implementation for converters):

import org.springframework.core.convert.converter.Converter;
import org.springframework.data.convert.ReadingConverter;
import org.springframework.data.convert.WritingConverter;

public enum Smoking {
    YES("yes"),
    NO("No");

    private String elasticsearchName;

    Smoking(String elasticsearchName) {
        this.elasticsearchName = elasticsearchName;
    }

    @WritingConverter
    public enum SmokingToStringConverter implements Converter<Smoking, String> {

        INSTANCE;

        @Override
        public String convert(Smoking source) {
            return source.elasticsearchName;
        }
    }

    @ReadingConverter
    public enum StringToSmokingConverter implements Converter<String, Smoking> {

        INSTANCE;

        @Override
        public Smoking convert(String source) {
            for (Smoking smoking : Smoking.values()) {
                if (smoking.elasticsearchName.equals(source)) {
                    return smoking;
                }
            }
            return null;
        }
    }
}

The converters need to be registered, this can be done in the configuration class (see the documentation about configuring the client at https://docs.spring.io/spring-data/elasticsearch/docs/4.0.4.RELEASE/reference/html/#elasticsearch.clients.rest) by adding a custom implementation of elasticsearchCustomConversions():

@Override
public ElasticsearchCustomConversions elasticsearchCustomConversions() {
    return new ElasticsearchCustomConversions(Arrays.asList(
        Smoking.SmokingToStringConverter.INSTANCE,
        Smoking.StringToSmokingConverter.INSTANCE)
    );
}

You then would use your enum class in your entity:

@Field(type = FieldType.Keyword)
private Smoking smoking;

That's all, the enum values are stored in Elasticsearch in the desired form.