DynamoDb查询枚举
[英]DynamoDb querying Enum
问题描述
I am new to dynamoDB and this question might be juvenile. 
我是dynamoDB的新手，这个问题可能是青少年问题。
I am trying to query an item from the table but dynamo api is not able to convert the query json result into the class instance because there is an enum variable member present in the class. 我正在尝试从表中查询项目，但dynamo api无法将查询json结果转换为类实例，因为类中存在枚举变量成员。
My class Structure:[note that RequestStage is a Enum member]
@DynamoDBTable(tableName = "LoadInfoProvider")
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public final class LoadInfoProvider {
/** The load request ID. */
@DynamoDBRangeKey
private String loadRequestID;
/** The load request creation id. */
@DynamoDBHashKey
private String loadRequestCreationId;
/** The carrier ID. */
private String carrierID;
/** The carrier pool. */
private String carrierPool;
/** The carrier details. */
private CarrierDetail carrierDetails;
/** The driver assignment required. */
private Boolean driverAssignmentRequired;
/** The driver pool. */
private String driverPool;
/** The trailer attachment required. */
private Boolean trailerAttachmentRequired;
/** The request type. */
private String requestType;
/** The request stage. */
private RequestStage requestStage;
/** The created time. */
private String createdTime;
/** The consumed time. */
private String consumedTime;
/** The provider status. */
private String providerStatus;
/** The is consumed. */
private Boolean isConsumed;
/** The request status. */
private RequestStatus requestStatus;
/** The trip. */
private Trip trip;
}
RequestStageEnum :
@NoArgsConstructor
@AllArgsConstructor(access = AccessLevel.PUBLIC)
@DynamoDBDocument
public enum RequestStage {
/** The initiated. */
INITIATED("initiated"),
/** The passed. */
PASSED("passed"),
/** The failed. */
FAILED("failed");
/** The value. */
@Getter
@Setter
private String value;
}
When i query something from this table, i am getting the below error. 当我从该表中查询某些内容时，出现以下错误。
Exception in thread "main" com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMappingException: Failed to instantiate new instance of class at com.amazonaws.services.dynamodbv2.datamodeling.ConversionSchemas$StandardItemConverter.createObject(ConversionSchemas.java:614) at com.amazonaws.services.dynamodbv2.datamodeling.ConversionSchemas$StandardItemConverter.unconvert(ConversionSchemas.java:414) at com.amazonaws.services.dynamodbv2.datamodeling.unmarshallers.ObjectUnmarshaller.unmarshall(ObjectUnmarshaller.java:54) at com.amazonaws.services.dynamodbv2.datamodeling.unmarshallers.NullableUnmarshaller.unmarshall(NullableUnmarshaller.java:46) at com.amazonaws.services.dynamodbv2.datamodeling.ConversionSchemas$StandardItemConverter.unmarshall(ConversionSchemas.java:593) at com.amazonaws.services.dynamodbv2.datamodeling.ConversionSchemas$StandardItemConverter.unconvert(ConversionSchemas.java:426) at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.privateMarshallIntoObject(D
It's clear from the exception, java is not able to instantiate the enum. 从异常可以明显看出，java无法实例化枚举。 How i can fix this and make this working? 我如何解决这个问题并使它正常工作？ Your help is appreciated and thanks. 非常感谢您的帮助。
1 个解决方案
解决方案1
1 已采纳 2018-04-04 11:32:28
You need to annotate your field requestStage with @DynamoDBMarshalling . 您需要使用@DynamoDBMarshalling注释字段requestStage 。
Assuming RequestStage is an enum , here's what your marshaller might look like: 假设RequestStage是一个enum ，则封送员可能是这样的：
public class RequestStageMarshaller implements DynamoDBMarshaller<RequestStage> {
@Override
public String marshall(RequestStage requestStage) {
return requestStage.toString();
}
@Override
public RequestStage unmarshall(Class<RequestStage> clazz, String
requestStage) {
return RequestStage.valueOf(requestStage);
}
}
Then you'd annotate your requestStage field like so: 然后，您可以这样注释您的requestStage字段：
@DynamoDBMarshalling(marshallerClass = RequestStageMarshaller.class)
private RequestStage requestStage
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