java - java中的batchGetItem API错误

Question

我正在查询的实体有一个 HashKey 和一个 RangeKey(数字)。当我在其上使用 batchGetItem 时，出现以下错误:

AWS Error Code: ValidationException, AWS Error Message: One or more parameter values were invalid: Mismatching attribute types between location and schema

架构:

Table: Daily

Hash Key: CustId (String)

Range Key: Dated (Number)

数据:

CustId : VisioNerdy

Dated : 1329071400000

代码:

  List<Key> fkeys = new ArrayList<Key>(); //tableName="Daily", keys=["VisioNerdy"], ranges=[1329071400000]
    Map<String, KeysAndAttributes> requestItems = new HashMap<String, KeysAndAttributes>();
    for(int i = 0; i < keys.size(); i++)
    {
        String key = keys.get(i);
        if(ranges == null)
            fkeys.add(new Key().withHashKeyElement(new AttributeValue().withS(key)));
        else
            fkeys.add(new Key().withHashKeyElement(new AttributeValue().withS(key))
                    .withRangeKeyElement(new AttributeValue().withS(ranges.get(i).toString())));
    }
    requestItems.put(tableName, new KeysAndAttributes().withKeys(fkeys));
    BatchGetItemRequest batchGetItemRequest = new BatchGetItemRequest().withRequestItems(requestItems);
    BatchGetItemResult result = client.batchGetItem(batchGetItemRequest);

有什么线索吗？

Answer 1

您已经定义了 Hash and Range Type Primary Key 的范围属性作为Number 类型，但通过withS() 为您的请求准备其属性值作为String 类型:

fkeys.add(new Key().withHashKeyElement(new AttributeValue().withS(key))
        .withRangeKeyElement(new AttributeValue().withS(ranges.get(i).toString())));

改变 withS(String s)至 withN(String s)应该相应地解决您的问题(令人困惑的是，这两种方法都需要 String 类型的参数):

fkeys.add(new Key().withHashKeyElement(new AttributeValue().withS(key))
        .withRangeKeyElement(new AttributeValue().withN(ranges.get(i).toString())));

诚然，DynamoDB data types 的隐式弱类型仅基于 String 参数提交并不能完全简化开发 ;)