java - 无法从 DynamoDB 加载数据，因为 List<Object> 类型的属性无法未转换并使用@DynamoDBDocument 保存

Question

我正在尝试使用@DynamoDBDocument 保存 List<CustomObject>，但它给了我一个 DynamoDBMappingException:无法取消转换属性。

这是我的实体类的样子 -

@lombok.Data
@DynamoDBTable(tableName = "carTable")
public class Car {
   @DynamoDBHashKey(attributeName = "name")
   private carName;

   @DynamoDBRangeKey(attributeName = "model")
   private carModel;

   @DynamoDBAttribute(attributeName = "manufacturers")
   private List<Manufacturer> manufacturers;
}

制造商类看起来像 -

@lombok.Data
@DynamoDBDocument
public class Manufacturer {
    @DynamoDBAttribute
    private String manufacturerName;
}

当使用此实体并将值保存到表中时，它会正确保存为 JSON，但在检索它时会抛出异常 -

com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMappingException: Car[manufacturers]; could not unconvert attribute
at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperTableModel.unconvert(DynamoDBMapperTableModel.java:271)
[junit]     at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.privateMarshallIntoObject(DynamoDBMapper.java:456)
[junit]     at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.load(DynamoDBMapper.java:422)
[junit]     at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.load(DynamoDBMapper.java:433)
[junit]     at com.amazonaws.services.dynamodbv2.datamodeling.AbstractDynamoDBMapper.load(AbstractDynamoDBMapper.java:85)

我在这里缺少什么，我需要在这里添加某种 TypeConverter 或 Marshaller 吗？

Answer 1

需要无参数构造函数来取消转换属性，将 @lombok.NoArgsConstructor 添加到 Manufacturer 类解决了我的问题。