DynamoDB Update API response filter

As you saw, you can only express what ReturnValues will accept: NONE, ALL_OLD, UPDATED_OLD, ALL_NEW, UPDATED_NEW

For details: https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateItem.html#API_UpdateItem_RequestSyntax

Why are you worried about returning too much?

Many thanks for the speedy reply.

The update is looped to a query that initiates the process. Once an item is queried, the update functionality updates an attribute that then conditionally prevents future queries.

Preferably I would like to limit the client's access to attributes that are of relevance. There are also attributes that I will be using to record activities in the background, which without a ProjectionExpression functionality, I will now be sharing with the client.

It does not sound feasible to superficially update all the attributes that I would like to share with the client, by going the ReturnValue: UPDATED_NEW route. If that is the only option...