Question

The entity i am querying has a HashKey & a RangeKey (Number). When i use batchGetItem on it, i get the following error:

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

Schema:

Table: Daily

Hash Key: CustId (String)

Range Key: Dated (Number)

Data:

CustId : VisioNerdy

Dated : 1329071400000

Code:

  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);

Any clues?

Answer 1

You have defined the range attribute of your Hash and Range Type Primary Key as type Number, yet prepare its attribute value via withS() as type String for your request:

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

Changing withS(String s) to withN(String s) should remedy your problem accordingly (confusingly both methods require a parameter of type String):

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

Admittedly, the implicit weak typing of the DynamoDB data types submission based on String parameters only doesn’t exactly ease developing 😉