Dynamodb get 查询返回输入字段之一为 null

Question

我有这个数据类

import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBAttribute;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBHashKey;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBRangeKey;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBTable;

@DynamoDBTable(tableName = "AtcDevDocumentImages")
public class ImageDetail {

  @DynamoDBHashKey(attributeName = "DocumentId")
  private String documentId;

  @DynamoDBRangeKey(attributeName = "TrackPosition")
  private int trackPosition;

  @DynamoDBAttribute(attributeName = "ImageId")
  private String imageId;

  @DynamoDBAttribute(attributeName = "ImageUrl")
  private String imageUrl;

  @DynamoDBAttribute(attributeName = "ImageName")
  private String imageName;

  @DynamoDBAttribute(attributeName = "Width")
  private double width;

  @DynamoDBAttribute(attributeName = "Height")
  private double height;
...
...
}

这是我的 dynamodb 表中的条目

这是我的服务类，执行 documentId 查询（获取文档 id x 的所有图像）：

import com.amazonaws.client.builder.AwsClientBuilder;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperConfig;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBQueryExpression;
import com.amazonaws.services.dynamodbv2.datamodeling.PaginatedQueryList;
import java.text.SimpleDateFormat;
import java.util.List;
import java.util.TimeZone;
import org.slf4j.Logger;

public class ImageService {

  private AmazonDynamoDB amazonDynamoDB;
  private DynamoDBMapper mapper;

  private SimpleDateFormat sdf;

  private String tableName;

  public ImageService local() {
    amazonDynamoDB =
        AmazonDynamoDBClientBuilder.standard()
            .withEndpointConfiguration(
                new AwsClientBuilder.EndpointConfiguration("http://localhost:8000", "local"))
            .build();
    mapper = new DynamoDBMapper(amazonDynamoDB);
    return this;
  }

  public ImageService cloud() {
    amazonDynamoDB = AmazonDynamoDBClientBuilder.standard().build();
    mapper = new DynamoDBMapper(amazonDynamoDB);
    this.tableName = System.getenv("IMAGES_TABLE");
    return this;
  }

  public ImageService init() {
    sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
    sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
    return this;
  }

  public List<ImageDetail> getImagesByDocumentId(String documentId, Logger logger) {
    DynamoDBMapperConfig mapperConfig =
        DynamoDBMapperConfig.builder()
            .withTableNameOverride(
                DynamoDBMapperConfig.TableNameOverride.withTableNameReplacement(tableName))
            .build();

    ImageDetail imageDetailKey = new ImageDetail();
    imageDetailKey.setDocumentId(documentId); // Ensure this sets the documentId field

    DynamoDBQueryExpression<ImageDetail> queryExpression =
        new DynamoDBQueryExpression<ImageDetail>()
            .withHashKeyValues(imageDetailKey)
            .withConsistentRead(false);

    PaginatedQueryList<ImageDetail> query =
        mapper.query(ImageDetail.class, queryExpression, mapperConfig);
    logger.info("results: ");
    logger.info(query.toString());
    return query;
  }
}

我得到的结果是这样的： 1703153761850，“2023-12-21 10:16:01 da71511d-f14e-48d2-8f33-ae623818745d 信息 XyzService-ImageDetail{documentId='a0d266bc-85ce-4595-a85d-fe1142c81fdf', id='null' , 轨道位置=6 , imageUrl='null', name='image1.png', width=1920.0, height=938.0}

我有点不明白为什么 imageId 和 imageUrl 为空。 欢迎任何建议或推荐。

Answer 1

可能是注解不够，除了注解数据类中的字段外，对应字段的getter方法还应该与dynamodb表项属性同名，即对于imageUrl，将url与ImageUrl注解还不够，属性本身需要被称为 imageUrl，或者至少它的 getter 应该被称为 getImageUrl()