def reserve_seat_on_flight()

in src/backend/catalog/src/reserve-flight/reserve.py [0:0]

• 19 lines of code
• 4 McCabe index (conditional complexity)

def reserve_seat_on_flight(flight_id):
    try:
        table.update_item(
            Key={"id": flight_id},
            ConditionExpression="id = :idVal AND seatCapacity > zero",
            UpdateExpression="SET seatCapacity = seatCapacity - :dec",
            ExpressionAttributeValues={
                ":idVal": flight_id,
                ":dec": 1,
                ":zero": 0
            },
        )

        return {
            'status': 'SUCCESS'
        }
    except dynamodb.meta.client.exceptions.ConditionalCheckFailedException as e:
        # Due to no specificity from the DDB error, this could also mean the flight
        # doesn't exist, but we should've caught that earlier in the flow.
        # TODO: Fix that. Could either use TransactGetItems, or Get then Update.
        raise FlightFullyBookedException(f"Flight with ID: {flight_id} is fully booked.")
    except ClientError as e:
        raise FlightReservationException(e.response['Error']['Message'])