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Yes, Spring Data for MongoDB can return null instead of an empty entity field by setting the useNullInsteadOfEmpty property to true in the MongoTemplate.

For example, in your MongoConfiguration class, you can add the following:

@Configuration
@EnableMongoRepositories(basePackages = "com.example.repository")
public class MongoConfiguration extends AbstractMongoConfiguration {

    @Override
    public MongoClient mongoClient() {
        return new MongoClient("localhost",27017);
    }

    @Override
    protected String getDatabaseName() {
        return "myDatabase";
    }

    @Bean
    public MongoTemplate mongoTemplate() {
        MappingMongoConverter converter = new MappingMongoConverter(mongoDbFactory(), new MongoMappingContext());
        converter.setMapKeyDotReplacement("_");
        converter.setUseNullInsteadOfEmpty(true); // set this to true
        return new MongoTemplate(mongoDbFactory(), converter);
    }
}

With this configuration, any empty entity fields will be returned as null when querying from the database.