具有另一个对象列表的对象的 DynamoDB Mapper 注释

问题描述

我正在尝试为以下情况创建一个 dynamoDBMapper 注释.

I am trying to create a dynamoDBMapper annotation for the below case.

我有 EmployeeLevelTrail，它是一个雇员级别记录的类

I have EmployeeLevelTrail which is a class of a Employee level record

@DynamoDBTable(tableName = TABLE_NAME)
public class EmployeeData {
    public final static String TABLE_NAME = "EmployeeDataRecord";

    @DynamoDBAttribute(attributeName = "employeeID")
    public String EmployeeID;

    @DynamoDBAttribute(attributeName = "EmployeeLevelDataRecords")
    @DynamoDBTyped(DynamoDBMapperFieldModel.DynamoDBAttributeType.M)
    public EmployeeLevelTrail employeeLevelTrail

}


public class EmployeeLevelTrail {

    public final static String DDB_ATTR_EMPLOYEE_LEVEL_TRAIL = "employeeLevelTrail";

    @DynamoDBAttribute(attributeName = DDB_ATTR_EMPLOYEE_LEVEL_TRAIL)
    private List<EmployeeLevelRecord> thisEmployeeLevelRecords;

    public void appendEmployeeLevelRecord(@NonNull EmployeeLevelRecord employeeLevelRecord) {

        thisEmployeeLevelRecords.add(employeeLevelRecord);

    }
}


public class EmployeeLevelRecord {

    private String Level;

    private String Manager;

    private Instant timeOfEvent;

}

这是我的注释，但它不正确，因为我无法保存我的 DynamoDB 数据

This is my annotation but it is not correct as I am not able to save my DynamoDB data

推荐答案

我使用以下代码找到了解决方案.仅使用@DynamoDBTypeConvertedJSON，我就能够在表中创建一个条目，但在遇到映射 Dynamo DB 映射异常时无法更新它.

I reached to the solution using the below code. With only @DynamoDBTypeConvertedJSON, I was able to create an entry in the table but not update it as I was running into mapping Dynamo DB mapping exception.

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@DynamoDBTable(tableName = TABLE_NAME)
public class EmployeeData {

    public final static String TABLE_NAME = "EmployeeData";

    public final static String DDB_ATTR_ID = "Id";

    public final static String DDB_ATTR_EMPLOYEE_LEVEL_RECORD_TRAIL = "EmployeeLevelRecordTrail";

    @DynamoDBHashKey(attributeName = DDB_ATTR_ID)
    @DynamoDBAttribute(attributeName = DDB_ATTR_ID)
    private String id;

    @DynamoDBAttribute(attributeName = DDB_ATTR_EMPLOYEE_LEVEL_RECORD_TRAIL)
    @DynamoDBTypeConverted(converter = EmployeeLevelRecordTrailConverter.class)
    private  EmployeeLevelRecordTrail  employeeLevelRecordTrail;

    @DynamoDBAttribute(attributeName = DDB_ATTR_CREATED_TIME)
    @DynamoDBTypeConverted(converter = InstantConverter.class)
    private Instant joiningTime;
}



@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class EmployeeLevelRecordTrail {

    private List<EmployeeLevelRecord> thisEmployeeLevelRecords;

    public void appendEmployeeLevelRecord(@NonNull EmployeeLevelRecord employeeLevelRecord) {

        thisEmployeeLevelRecords.add(employeeLevelRecord);

    }
}


@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@DynamoDBDocument
public class EmployeeLevelRecord {

    private String Level;

    private String Manager;

    @DynamoDBTypeConverted(converter = InstantConverter.class)
    private Instant timeOfEvent;

}

public class EmployeeLevelRecordTrailConverter implements
        DynamoDBTypeConverter<List<EmployeeLevelRecord>, EmployeeLevelRecordTrail> {

    @Override
    public List<EmployeeLevelRecord> convert(EmployeeLevelRecordTrail employeeLevelRecordTrail) {
        return employeeLevelRecordTrail.getEmployeeLevelRecord();
    }

    @Override
    public EmployeeLevelRecordTrail unconvert(List<EmployeeLevelRecord> thisEmployeeLevelRecords) {
        return new EmployeeLevelRecordTrail(thisEmployeeLevelRecords);
    }
}

public class InstantConverter implements DynamoDBTypeConverter<String, Instant> {

    private static final DateTimeFormatter DATE_TIME_FORMATTER = DateTimeFormatter.ISO_INSTANT;

    @Override
    public String convert(Instant instant) {
        return instant == null ? null : DATE_TIME_FORMATTER.format(instant);
    }

    @Override
    public Instant unconvert(String str) {
        return str == null ? null : Instant.from(DATE_TIME_FORMATTER.parse(str));
    }
}

阅读有关如何进行映射的文档很有帮助.

Reading the documentation on how to do mapping helped.

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