我正在尝试为mongodb中发生的任何更改设置更新缓存机制。为此，我实现了一个侦听器：

@Bean
    public MessageListenerContainer messageListenerContainer(MongoTemplate template){
        MessageListenerContainer messageListenerContainer = new DefaultMessageListenerContainer(template);
        messageListenerContainer.start();
        ChangeStreamRequest<BinDataItem> request = ChangeStreamRequest.builder()
                .collection("BIN")
                .publishTo(getBinListener())
                .build();
        messageListenerContainer.register(request, BinDataItem.class);
        return messageListenerContainer;
    }

    @Bean
    @Qualifier("BinDataUpdateListener")
    public BinDataUpdateListener<ChangeStreamDocument<Document>, BinDataItem> getBinListener(){
        return new BinDataUpdateListener<ChangeStreamDocument<Document>, BinDataItem>();
    }

方法的更新是：

public class BinDataUpdateListener<C, T> implements MessageListener<ChangeStreamDocument<Document>, BinDataItem> {

    @Autowired
    @Qualifier("binDataLoader")
    CacheManager cacheManager;

    @Override
    public void onMessage(Message<ChangeStreamDocument<Document>, BinDataItem> message) {
           BinDataItem binDataItem = (BinDataItem)message.getBody(); // this value comes as null for a delete operation
           String operationType = message.getRaw().getOperationType().getValue();
           try {
               cacheManager.updateCache(operationType, binDataItem, message.getRaw().getDocumentKey());
           }
           catch(RedisCommandTimeoutException ex){
               addToSLogger(DomainConstants.GET_BIN_DATA_STRING, DomainConstants.ERR_CODE_MS1003, ex);
               throw ex;
           }
           catch(RedisBusyException ex){
               addToSLogger(DomainConstants.GET_BIN_DATA_STRING, DomainConstants.ERR_CODE_MS1002, ex);
               throw ex;
           }
           catch(RedisConnectionFailureException ex){
               addToSLogger(DomainConstants.GET_BIN_DATA_STRING, DomainConstants.ERR_CODE_MS1002, ex);
               throw ex;
           }
           catch(Exception ex){
               addToSLogger(DomainConstants.GET_BIN_DATA_STRING, DomainConstants.ERR_CODE_MS1001, ex);
               throw ex;
           }
    }

    private void addToSLogger(String messageName, String errorCode, Exception e){
        Slogger.get()
                .withTag(DomainConstants.MSG_ERROR)
                .withField(DomainConstants.MSG_NAME, messageName)
                .withField(DomainConstants.ERR_CODE, errorCode)
                .withThrowable(e)
                .info(e.getMessage());
    }

}

bindataitem pojo是：

@Document(collection = "BIN")
@JsonIgnoreProperties(ignoreUnknown=true)
public class BinDataItem implements Serializable {
    @BsonProperty(value = "_id")
    private String id;
    private String bin;
}

问题是，每当发生delete类型的事件时，被删除的对象在程序中都是null。我需要mongo中已删除对象的字段bin来在redis缓存中删除它。我知道如何获取objectid，但其他所有字段我都不知道。