How to query the closest item to timestamp in Dynamo DB with Scala-CodePudding

I am using the AWS Dynamo DB library for Scala - com.amazonaws.services.dynamodbv2.

Earlier I had a table with a primary key and I was using GetItem to get specific item from it like so :

val item = Try(Option(ddb.getItem(new GetItemRequest().withTableName(table).withKey(Collections.singletonMap(keyField, new AttributeValue(key)))).getItem).map(_.get(valField).getS))

But now I need to start using a new sort key (timestamp of the created date) on top.

This way I can have multiple identical primary keys with different timestamp sort keys. This is meant so I will be able to get the closest item to my current sort timestamp property.

I think I need KeyConditionExpression where my input timestamp is bigger or equal to the new sort key, and I saw a property ScanIndexForward which can be set to true in combination with limit = 1 so I will get only one item and it will be the closest(?)

And this should get me the desired item I hope, but I am not so sure how to approach this in Scala and with the AWS library.

CodePudding user response：

In case anyone interested, this is what worked out for me -

val queryRequest = new QueryRequest().withTableName(table)
          .withKeyConditions(createKeyConditionsMap(keyField, keyValue, sortField, sortValue))
          .withScanIndexForward(false)
          .withLimit(1)
val x = ddb.query(queryRequest).getItems()

  def createKeyConditionsMap(keyField: String, keyValue: String, sortField: String, sortValue: String) = {
    Map(keyField -> new Condition().withComparisonOperator("EQ").withAttributeValueList(new AttributeValue(keyValue)),
    sortField -> new Condition().withComparisonOperator("LE").withAttributeValueList(new AttributeValue().withN(sortValue))).asJava
  }