Spring Mongo聚合与LocalDateTime问题

Question

原因：org.bson.codecs.configuration.codecConfigurationException：找不到java.time.LocalDateTime类的编解码器。

使用下面的代码

@SpringBootApplication
public class MongojavatimeApplication implements CommandLineRunner {

    @Autowired
    private MongoTemplate template;

    public static void main(String[] args) {
        SpringApplication.run(MongojavatimeApplication.class, args);
    }

    @Override
    public void run(String... args) throws Exception {
        Criteria c = Criteria.where("createdDate").gt(LocalDateTime.now().minusDays(30));
        template.aggregate(Aggregation.newAggregation(Aggregation.match(c)), "TestJavaTime", TestJavaTime.class);
    }
}

您将在这里找到很少的测试，LocalDateTime可以很好地使用Spring存储库，这是使用MongoTemplate使用Criteria API的经典查询，但在创建聚合查询时会引发此错误。https://github.com/farael49/spring-mongo-aggrege-localdateTime

Answer 1

如果要直接使用LocalDateTime，则应提供如下所示的编解码器：

public enum LocalDateTimeCodec
        implements Codec<LocalDateTime> {

    INSTANCE;

    @Override
    public void encode(
            BsonWriter writer,
            LocalDateTime value,
            EncoderContext encoderContext) {

        writer.writeDateTime(
                value.toInstant(ZoneOffset.UTC)
                     .toEpochMilli()
        );
    }

    @Override
    public LocalDateTime decode(
            BsonReader reader,
            DecoderContext decoderContext) {

        return Instant.ofEpochMilli(reader.readDateTime())
                .atOffset(ZoneOffset.UTC)
                .toLocalDateTime();
    }

    @Override
    public Class<LocalDateTime> getEncoderClass() {
        return LocalDateTime.class;
    }
}

您可以通过以下方式注册：

@Bean
public MongoDbFactory mongoDbFactory() throws Exception {
    CodecRegistry registry = CodecRegistries.fromRegistries(
        CodecRegistries.fromCodecs(LocalDateTimeCodec.INSTANCE),
        MongoClient.getDefaultCodecRegistry()
    );
    MongoClientOptions options = MongoClientOptions
        .builder()
        .codecRegistry(registry)
        .build();
    return new SimpleMongoDbFactory(new MongoClient(host, options), dbName);
}

其中host和dbname可能是某个配置类的autowired字段。