Unable to Upsert data in DynamoDB using WriteRequest JAVA

Question

I have a java application which is building a DynamoDB client write request as

WriteRequest.builder().putRequest(PutRequest.builder().item(attributeValueMap).build()).build();

The above request is replacing the items with same PartitionKey and SortKey instead of upserting the data into the table. Any idea what am I doing wrong or do I need a to pass any additional parameter in PutRequest ?

Answer 1

As the commenter mentions, you want to use UpdateItem if you want to "patch" an item. PutItem will replace the entire item. You can read more about the differences here: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/WorkingWithItems.html#WorkingWithItems.WritingData

This is a simplified code sample for how that works in Javav2 SDK.

HashMap<String,AttributeValue> itemKey = new HashMap<>();
itemKey.put(key, AttributeValue.builder()
    .s(keyVal)
    .build());

HashMap<String,AttributeValueUpdate> updatedValues = new HashMap<>();
// Put your attributes/values you wish to update here. 
// Attributes you don't include won't be effected by the update
updatedValues.put(name, AttributeValueUpdate.builder()
    .value(AttributeValue.builder().s(updateVal).build())
    .action(AttributeAction.PUT)
    .build());

UpdateItemRequest request = UpdateItemRequest.builder()
    .tableName(tableName)
    .key(itemKey)
    .attributeUpdates(updatedValues)
    .build();

ddb.updateItem(request);