func updateStory(update string) (events.APIGatewayProxyResponse, error) {...}

pt-11.main.go

func updateStory(ctx context.Context, update string) (events.APIGatewayProxyResponse, error) {
	var raw Story // <--- this line and the following two are important here because if we didn't do this
	data := []byte(update) // we wouldn't be able to use the incoming data as is since it is of type `string`.
	if err := json.Unmarshal(data, &raw); err != nil {
		handleError(err)
	}

	filter := bson.D{{"_id", raw.ID}} // <-- this is how we access those objects
	upDate := bson.D{{"$set", bson.D{{"likes", raw.Likes}}}}
	result, err := collection.UpdateOne(ctx, filter, upDate)
	if err != nil {
		return handleError(err)
	}

	newDbResult = DbResults{result, nil}
	return handleResultSendDbResponse("UpdateResult")
}