仅使用hashKey查询dynamoDB [英] Query dynamoDB using only hashKey

问题描述

我只想使用Hashkey查询dynamoDB。
我的表（名称= testTable）架构如下：

I want to query my dynamoDB using only the Hashkey. My table(name = testTable) schema is as follows:

• 字符串自动ID（哈希键）


• 字符串AlexandriaID（RangeKey）


• 字符串docType

我的dynamoDBQueryExpression是：

My dynamoDBQueryExpression is:

String hashKey = "dummyHashKey";

testTable hashKeyValues = new testTable();

hashKeyValues.setAutoID(hashKey);

DynamoDBQueryExpression<testTable> queryExpression = new DynamoDBQueryExpression<testTable>();
queryExpression.withHashKeyValues(hashKeyValues);

//Assuming I have a dynamoDBMapper object mapper

List<testTable> docList = mapper.query(testTable.class, queryExpression);

---

我期望有相同的testTable对象列表autoID。

---

I am expecting a list of testTable objects having same autoID. As I am new to this, please correct me if I am wrong.

当我制作 mapper.query（）调用。

请参考Vikdor在StackOverflow问题上的评论

Referring comment by Vikdor at the StackOverflow question query using hashKey in dynamoDB

进一步编辑：

我的确切查询方法：

public void queryFromRFIDocumentDetails(String hashKey){
    System.out.println((new Throwable()).getStackTrace()[0].toString() + "***Enter***");

    testTable hashKeyValues = new testTable();
    hashKeyValues.setAutoID(hashKey);

    System.out.println("AutoID for hashKeyValues " + hashKeyValues.getAutoID());
    System.out.println("DocTYpe for hashKeyValues " + hashKeyValues.getDocType());
    System.out.println("AlexandriaID for hashKeyValues " + hashKeyValues.getAlexandraiID());

    DynamoDBQueryExpression<testTable> queryExpression = new DynamoDBQueryExpression<testTable>();
    queryExpression.withHashKeyValues(hashKeyValues);
    queryExpression.withConsistentRead(false);

    System.out.println("calling mapper.query");  //nothing happens after this

    List<testTable> docList = new ArrayList<testTable>();
    docList = mapper.query(testTable.class, queryExpression);

    for(int i=0; i<docList.size(); i++){
        System.out.println("***iterating at retrieved index " + i);
        System.out.println("AutoID for retrieved document " + docList.get(i).getAutoID());
        System.out.println("DocTYpe for retrieved document " + docList.get(i).getDocType());
        System.out.println("AlexandriaID for retrieved document " + docList.get(i).getAlexandraiID());
    }
}

我的程序的堆栈跟踪：

将对象保存到表中的调用方法：

Calling method to save objects in the table:

***iterating at index 0
[java] AutoID for document to be saved abc
[java] DocTYpe for document to be saved foo
[java] AlexandriaID for document to be saved id1
[java] com.amazon.sduservice.db.dynamoDB.saveInRFIDocumentDetails(dynamoDB.java:201)***Enter***
[java] com.amazon.sduservice.db.dynamoDB.saveInRFIDocumentDetails(dynamoDB.java:203)***Exit***
[java] ***iterating at index 1
[java] AutoID for document to be saved abc
[java] DocTYpe for document to be saved foo
[java] AlexandriaID for document to be saved id2
[java] com.amazon.sduservice.db.dynamoDB.saveInRFIDocumentDetails(dynamoDB.java:201)***Enter***
[java] com.amazon.sduservice.db.dynamoDB.saveInRFIDocumentDetails(dynamoDB.java:203)***Exit***
[java] ***iterating at index 2
[java] AutoID for document to be saved abc
[java] DocTYpe for document to be saved foo
[java] AlexandriaID for document to be saved id3
[java] com.amazon.sduservice.db.dynamoDB.saveInRFIDocumentDetails(dynamoDB.java:201)***Enter***
[java] com.amazon.sduservice.db.dynamoDB.saveInRFIDocumentDetails(dynamoDB.java:203)***Exit***
[java] hashKey is abc

基于autoID的查询表的调用方法：

Calling method to query the table on the basis of autoID:

[java] com.amazon.sduservice.db.dynamoDB.queryFromRFIDocumentDetails(dynamoDB.java:207)***Enter***
[java] AutoID for hashKeyValues abc
[java] DocTYpe for hashKeyValues null
[java] AlexandriaID for hashKeyValues null
[java] calling mapper.query

扫描表上的操作输出：

Scanning Table RFIDocumentDetails
 [java] {docType={S: foo,}, autoID={S: abc,}, alexandriaID={S: id1,}}
 [java] {docType={S: foo,}, autoID={S: abc,}, alexandriaID={S: id2,}}
 [java] {docType={S: foo,}, autoID={S: abc,}, alexandriaID={S: id3,}}
 [java] {docType={S: pdf,}, autoID={S: HashKey,}, alexandriaID={S: alexandriaID1,}}
 [java] {docType={S: pdf,}, autoID={S: HashKey,}, alexandriaID={S: alexandriaID2,}}
 [java] {docType={S: foo,}, autoID={S: asdf,}, alexandriaID={S: id1,}}
 [java] {docType={S: foo,}, autoID={S: asdf,}, alexandriaID={S: id2,}}
 [java] {docType={S: foo,}, autoID={S: foo,}, alexandriaID={S: id1,}}
 [java] {docType={S: foo,}, autoID={S: foo,}, alexandriaID={S: id2,}}
 [java] Scanning Table Finishes 

testTable类：

testTable Class:

public class testTable {    
   private String autoID;   
   private String docType;  
   private String alexandriaID;     

   @DynamoDBHashKey(attributeName="autoID") 
   public String getAutoID(){   return autoID;} 
   public void setAutoID(String autoID){    this.autoID = autoID;}      

   @DynamoDBRangeKey(attributeName="alexandriaID")  
   public String getAlexandraiID(){ return alexandriaID;}   
   public void setAlexandriaID(String alexandriaID){    this.alexandriaID = alexandriaID;}      

   @DynamoDBAttribute(attributeName="docType")  
   public String getDocType(){  return docType;}    
   public void setDocType(String docType){  this.docType = docType;}    

}

推荐答案

，问题似乎出在getAlexandraiID声明中。

As discussed, the problem seems to be in getAlexandraiID declaration.

请按如下所述更改方法名称：-

Please change the method name as mentioned below:-

发件人：-

public String getAlexandraiID(){ return alexandriaID;} 

收件人：-

@DynamoDBRangeKey(attributeName = "alexandriaID")
public String getAlexandriaID() {
    return alexandriaID;
}

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