Dynamodb with list.append in Java

Question

Currently my dynamodb has a key is batch_id and then a list 'doc_info_list'. I would like to add to the list with below code.

But it is showing an exception

com.amazonaws.services.dynamodbv2.model.AmazonDynamoDBException: ExpressionAttributeValues contains invalid value: One or more parameter values were invalid: An AttributeValue may not contain an empty string for key :val1 (Service: AmazonDynamoDBv2; Status Code: 400; Error Code: ValidationException; Request ID: 03LRKK3J3SBVFNGMKV36NVSQBJVV4KQNSO5AEMVJF66Q9ASUAAJG)

Code:

AmazonDynamoDB amazonDynamoDBClient = AmazonDynamoDBClientBuilder.defaultClient();
        DynamoDB dynamoDB = new DynamoDB(amazonDynamoDBClient);
        Table table = dynamoDB.getTable("XXXX");

        String currentDateTime = MiscHelper.getDateTimeAsISO8601();

        Map<String, Object> map = objectMapper.convertValue(doc, Map.class);

        ValueMap valueMap = new ValueMap().withList(":val1", Arrays.asList(map));
        valueMap.withList(":empty_list", new ArrayList<>());
        valueMap.withString(":val2", currentDateTime);
        UpdateItemSpec updateItemSpec = new UpdateItemSpec().withPrimaryKey("batch_id", batchId)
                .withUpdateExpression("set doc_info_list = list_append(if_not_exists(doc_info_list, :empty_list), :val1), created_date_time = :val2, updated_date_time = :val2")
                .withValueMap(valueMap)
                .withReturnValues(ReturnValue.UPDATED_NEW);

What am I doing wrong here?

What's a doc? Is this a DynamoDb entity object?

Nestor Sokil
– Nestor Sokil

2019-03-30 09:35:08 +00:00
Commented Mar 30, 2019 at 9:35 — Nestor Sokil
– Nestor Sokil, Commented Mar 30, 2019 at 9:35
Doc is a normal pojo object.

Nghia Do
– Nghia Do

2019-03-30 09:37:24 +00:00
Commented Mar 30, 2019 at 9:37 — Nghia Do
– Nghia Do, Commented Mar 30, 2019 at 9:37

Nestor Sokil · Accepted Answer · 2019-03-30 09:40:32Z

1

So, you're trying to save doc into dynamodb through a Map representation. The only problem I might guess is that some of your doc fields are an empty String and then you're trying to save it as Dynamo's AttributeValue and this is not allowed: https://forums.aws.amazon.com/thread.jspa?threadID=90137

answered Mar 30, 2019 at 9:40

Nestor Sokil

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5 Comments

Nghia Do Over a year ago

You are totally right. I have a field which contains a blank data. My bad I did not find it out. Thank again.

Nghia Do Over a year ago

By the way, is my implementation is a good approach. Could we use DynamoDBMapper with Entity (using Annotation) for this use case?

Nestor Sokil Over a year ago

I don't see why not. With a mapper you could at least skip the map transformation.

Nghia Do Over a year ago

do you have an example I can refer which using list_append & DynamoDBMapper

Nestor Sokil Over a year ago

I mean you could leave most of your code as is, just skip the objectMapper.convertValue(doc, Map.class). As to if SDK with mapper can take care of the more complex queries like the one you have - I don't think so. But you can open another question, maybe someone will know for sure. :)

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