DynamoDBMapper 不工作 - 保存批处理记录会引发 @DynamoDBTyped 或 @DynamoDBTypeConverted 错误

Question

我想做什么？ -我想使用 DynamoDBMapper 将一批记录保存到 DynamoDB。

模型类

package model;

import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBAttribute;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBAutoGeneratedKey;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBDocument;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBHashKey;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBTable;

@DynamoDBTable(tableName = "jobTable")
public final class MapperModel {
    public String jobId;
    public String jobName;
    public Stringparams stringparams[];
    public String url;
    public String source;
    public String[] target;
    public String contentType;
    public String dueDate;
    public Metadata metadata;

    /** getters start here **/
    @DynamoDBHashKey(attributeName = "jobId")
    public String getJobId() {
        return jobId;
    }

    @DynamoDBAttribute(attributeName = "jobName")
    public String getJobName() {
        return jobName;
    }

    @DynamoDBAttribute(attributeName = "url")
    public String getURL() {
        return url;
    }

    @DynamoDBAttribute(attributeName = "strings")
    public Stringparams[] getStrings() {
        return stringparams;
    }


    @DynamoDBAttribute(attributeName = "source")
    public String getSource() {
        return source;
    }

    @DynamoDBAttribute(attributeName = "target")
    public String[] getTarget() {
        return target;
    }

    @DynamoDBAttribute(attributeName = "contentType")
    public String getContentType() {
        return contentType;
    }

    @DynamoDBAttribute(attributeName = "dueDate")
    public String getDueDate() {
        return dueDate;
    }

    @DynamoDBAttribute(attributeName = "metadata")
    public Metadata getMetadata() {
        return metadata;
    }

    /** setters start here **/

    public void setJobId(String string) {
        this.jobId = string;
    }

    public void setJobName(String jobName) {
        this.jobName = jobName;
    }

    public void setStrings(Stringparams[] strings) {
        this.stringparams = strings;
    }

    public void setURL(String url) {
        this.url = url;
    }

    public void setSource(String source) {
        this.source = source;
    }

    public void setTarget(String[] target) {
        this.target = target;
    }

    public void setContentType(String contentType) {
        this.contentType = contentType;
    }

    public void setDueDate(String dueDate) {
        this.dueDate = dueDate;
    }

    public void setMetadata(Metadata metadata) {
        this.metadata = metadata;
    }

    @DynamoDBDocument
    public static final class Stringparams {
        @DynamoDBAutoGeneratedKey
        public String key;
        public String value;
        public String description;

        public String getKey() {
            return key;
        }

        public void setKey(String key) {
            this.key = key;
        }

        @DynamoDBAttribute(attributeName = "value")
        public String getValue() {
            return value;
        }

        public void setValue(String value) {
            this.value = value;
        }

        @DynamoDBAttribute(attributeName = "description")
        public String getDescription() {
            return description;
        }

        public void setDescription(String description) {
            this.description = description;
        }

    }

    @DynamoDBDocument
    public static final class Metadata {
        public String invoicingCategory;
        public String invoicingRegion;
        public String referenceURL;

        public void setInvoicingCategory(String invoicingCategory) {
            this.invoicingCategory = invoicingCategory;
        }

        public void setInvoicingRegion(String invoicingRegion) {
            this.invoicingRegion = invoicingRegion;
        }

        public void setReferenceURL(String referenceURL) {
            this.referenceURL = referenceURL;
        }

        @DynamoDBAttribute(attributeName = "invoicingCategory")
        public String getInvoicingCategory() {
            return invoicingCategory;
        }

        @DynamoDBAttribute(attributeName = "invoicingRegion")
        public String getInvoicingRegion() {
            return invoicingRegion;
        }

        @DynamoDBAttribute(attributeName = "referenceURL")
        public String getReferenceURL() {
            return referenceURL;
        }

    }
}

public class Test {

    ......
    .......

    public void persistRecordsToDataStore(List<MapperModel> 
                                          requestModelList) 
    {

                AmazonDynamoDB amazonDynamoDBClient = new 
                                       AmazonDynamoDBClient();
                DynamoDBMapper dynamoDBMapper = new  
                                     DynamoDBMapper(amazonDynamoDBClient);


     amazonDynamoDBClient.setRegion(Region.getRegion(Regions.US_WEST_2));

     boolean insertStatus = insertRecords(dynamoDBMapper, requestModelList)

   }     


   public static boolean insertRecords(DynamoDBMapper dynamoDBMapper,
                    List<MapperModel> requestModelList) 
   {
      for (MapperModel requestModel : requestModelList) 
      {
        dynamoDBMapper.save(requestModel);
      }

       return true;
   }

        ......
        ......
   }

问题：我看到一个错误不支持；需要@DynamoDBTyped 或@DynamoDBTypeConverted。任何人都可以帮助我理解和分享修复吗？

Answer 1

使用注解@DynamoDBDocument有更简单的方法

比如上面的java类，

@DynamoDBDocument
public class Metadata {
    private Stirng aa;
    private int bb;
}

那么它应该可以工作

Answer 2

我已经从亚马逊文档http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBMapper.ArbitraryDataMapping.html找到了答案

我的问题的解决方案

    @DynamoDBTable(tableName = "jobTable")

    public final class MapperModel {
    public String jobId;
    public String jobName;
    public Stringparams stringparams[];
    public String url;
    public String source;
    public String[] target;
    public String contentType;
    public String dueDate;
    public Metadata metadata;

    @DynamoDBHashKey(attributeName = "jobId")
    public String getJobId() {
        return jobId;
    }

    @DynamoDBAttribute(attributeName = "jobName")
    public String getJobName() {
        return jobName;
    }

    @DynamoDBAttribute(attributeName = "url")
    public String getURL() {
        return url;
    }

    **@DynamoDBTypeConverted(converter= StringparamsTypeConverter.class)**
    public Stringparams[] getStrings() {
        return stringparams;
    }


    @DynamoDBAttribute(attributeName = "source")
    public String getSource() {
        return source;
    }

    @DynamoDBAttribute(attributeName = "target")
    public String[] getTarget() {
        return target;
    }

    @DynamoDBAttribute(attributeName = "contentType")
    public String getContentType() {
        return contentType;
    }

    @DynamoDBAttribute(attributeName = "dueDate")
    public String getDueDate() {
        return dueDate;
    }

    **@DynamoDBTypeConverted(converter = MetadataTypeConverter.class)**
    public Metadata getMetadata() {
        return metadata;
    }

    /** setters start here **/

    public void setJobId(String string) {
        this.jobId = string;
    }

    public void setJobName(String jobName) {
        this.jobName = jobName;
    }

    public void setStrings(Stringparams[] strings) {
        this.stringparams = strings;
    }

    public void setURL(String url) {
        this.url = url;
    }

    public void setSource(String source) {
        this.source = source;
    }

    public void setTarget(String[] target) {
        this.target = target;
    }

    public void setContentType(String contentType) {
        this.contentType = contentType;
    }

    public void setDueDate(String dueDate) {
        this.dueDate = dueDate;
    }

    public void setMetadata(Metadata metadata) {
        this.metadata = metadata;
    }
}

我只提供一个 ObjectType 转换器的代码。

public class MetadataTypeConverter implements DynamoDBTypeConverter<String, Metadata> {

    @Override
    public String convert(final Metadata metadata) {
        String metadataValue = null;
        try {
            .....
            .....
            your custom code
        } catch (JsonProcessingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return metadataValue;
    }

    @Override
    public Metadata unconvert(final String jsonData) {
        Metadata metadataType = null;
        try {
            .....
            .....
            your custom code
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return metadataType;
    }

}

Answer 3

您缺少自定义类元数据的 DynamoDB 转换。 您可以编写自己的转换器，也可以使用 @DynamoDBTypeConverted 属性并将自定义类名指定为参数。

Answer 4

这里有一个使用 DynamoDBTypeConverted 的示例： http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBMapper.ArbitraryDataMapping.html

Answer 5

就我而言，问题在于我没有意识到 DynamoDB 映射器会自动尝试映射所有公共方法。我花了很长时间才发现这一点，因为错误消息没有报告它失败的属性。

可以这样解决：

@DynamoDBIgnore
public SomeNonMappableObject getThing() {
   ...
}