AmazonDynamoDBException in Java

Question

Hello,

I'm using the below java code to get from DynamoDB all the items for a Partition Key. Table has a Partition Key (PK) and a Sort Key (SK) that are Strings.

```
TableKeysAndAttributes tableKeysAndAttributes = new TableKeysAndAttributes(tableDetails.getTableName())
    	.withHashOnlyKeys(tableDetails.getTablePKName(), tableDetails.getTablePKValue())
    	.withProjectionExpression("document");
    	
BatchGetItemOutcome outcome = dynamoClient.batchGetItem(tableKeysAndAttributes);
```
I got the below error, as in the case when I should send also the SK to the database, while the API supports only PK:

```
com.amazonaws.services.dynamodbv2.model.AmazonDynamoDBException: The provided key element does not match the schema (Service: AmazonDynamoDBv2; Status Code: 400; Error Code: ValidationException; Request ID:  
 LGT808CBEEL6CEN8EMATK07R0JVV4KQNSO5AEMVJF66Q9ASUAAJG; Proxy: null): java.lang.RuntimeException java.lang.RuntimeException: com.amazonaws.services.dynamodbv2.model.AmazonDynamoDBException: The provided key element does not match the schema (Service: AmazonDynamoDBv2; Status Code: 400; Error Code: ValidationException; Request ID:  
 LGT808CBEEL6CEN8EMATK07R0JVV4KQNSO5AEMVJF66Q9ASUAAJG; Proxy: null) at  
 com.amazonaws.lambda.mihai.translate.handler.LambdaFunctionHandler.handleRequest(LambdaFunctionHandler.java:79) at  
 com.amazonaws.lambda.mihai.translate.handler.LambdaFunctionHandler.handleRequest(LambdaFunctionHandler.java:26) Caused by:  
 com.amazonaws.services.dynamodbv2.model.AmazonDynamoDBException: The provided key element does not match the schema (Service: AmazonDynamoDBv2; Status Code: 400; Error Code: ValidationException; Request ID:  
 LGT808CBEEL6CEN8EMATK07R0JVV4KQNSO5AEMVJF66Q9ASUAAJG; Proxy: null) at  
 com.amazonaws.http.AmazonHttpClient$RequestExecutor.handleErrorResponse(AmazonHttpClient.java:1879) at  
 com.amazonaws.http.AmazonHttpClient$RequestExecutor.handleServiceErrorResponse(AmazonHttpClient.java:1418) at  
 com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeOneRequest(AmazonHttpClient.java:1387) at  
 com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeHelper(AmazonHttpClient.java:1157) at  
 com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:814) at  
 com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:781) at  
 com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:755) at  
 com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:715) at  
 com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:697) at  
 com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:561) at  
 com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:541) at  
 com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.doInvoke(AmazonDynamoDBClient.java:6999) at  
 com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.invoke(AmazonDynamoDBClient.java:6966) at  
 com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.executeBatchGetItem(AmazonDynamoDBClient.java:607) at  
 com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.batchGetItem(AmazonDynamoDBClient.java:571) at  
 com.amazonaws.services.dynamodbv2.document.internal.BatchGetItemImpl.doBatchGetItem(BatchGetItemImpl.java:98) at  
 com.amazonaws.services.dynamodbv2.document.internal.BatchGetItemImpl.batchGetItem(BatchGetItemImpl.java:57) at  
 com.amazonaws.services.dynamodbv2.document.DynamoDB.batchGetItem(DynamoDB.java:153) at  
 com.amazonaws.lambda.mihai.servicecommons.service.DynamoAbstractService.getPartitionKeyDocuments(DynamoAbstractService.java:229) at  
```
Could you please specify why do I have the error in this case ?

Thank you,  
Mihai ADAM

Answer

The API which you need to use is [`Query`](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Query.html) which allows you to get all items related to a single partition key.

> You must provide the name of the partition key attribute and a single value for that attribute. Query returns all items with that partition key value. Optionally, you can provide a sort key attribute and use a comparison operator to refine the search results.

```
AmazonDynamoDB client = AmazonDynamoDBClientBuilder.standard()
.withRegion(Regions.US_WEST_2).build();
DynamoDB dynamoDB = new DynamoDB(client);

Table table = dynamoDB.getTable("Reply");

QuerySpec spec = new QuerySpec()
    .withKeyConditionExpression("Id = :v_id")
    .withValueMap(new ValueMap()
        .withString(":v_id", "Amazon DynamoDB#DynamoDB Thread 1"));

ItemCollection items = table.query(spec);

Iterator iterator = items.iterator();
Item item = null;
while (iterator.hasNext()) {
    item = iterator.next();
    System.out.println(item.toJSONPretty());
}
```

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/QueryingJavaDocumentAPI.html

Answer

If you have also sort key in the table, yo need to provide that as well. If so you may need to use another method: https://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/services/dynamodbv2/document/TableKeysAndAttributes.html#withHashAndRangeKeys-java.lang.String-java.lang.String-java.lang.Object...-

AmazonDynamoDBException in Java

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