def start_ride_txn(session, vehicle_id, user_email):
"""
Start a vehicle ride (or continue if the vehicle is already in use).
Arguments:
session {.Session} -- The active session for the database connection.
vehicle_id {String} -- The vehicle's `id` column.
"""
# find the row where we want to start the ride.
# SELECT * FROM vehicles WHERE id = <vehicle_id> AND in_use = false
# LIMIT 1;
vehicle = session.query(Vehicle).filter(Vehicle.id == vehicle_id). \
filter(Vehicle.in_use == False).first()
if vehicle is None:
return None
# SELECT * FROM location_history WHERE vehicle_id = <vehicle_id>
# ORDER BY ts DESC LIMIT 1;
last_chx = session.query(LocationHistory). \
filter(LocationHistory.vehicle_id ==
vehicle_id). \
order_by(LocationHistory.ts.desc()). \
first()
new_location_history_id = str(uuid4())
new_timestamp = func.now()
new_location_history_row = LocationHistory(id=new_location_history_id,
vehicle_id=vehicle_id,
longitude=last_chx.longitude,
latitude=last_chx.latitude,
ts=new_timestamp)
new_ride_id = str(uuid4())
new_ride_row = Ride(id=new_ride_id,
vehicle_id=vehicle_id,
user_email=user_email,
start_ts=new_timestamp,
end_ts=None)
# UPDATE vehicles SET in_use = true WHERE vehicles.id = <vehicle_id>
vehicle.in_use = True
vehicle.last_checkin = func.now()
session.add(new_location_history_row)
session.flush()
session.add(new_ride_row)
return True # Just making it explicit that this worked.
def start_ride_txn(session, city, rider_id, vehicle_id):
"""
Insert a new row into the rides table and update a row of the vehicles table.
Arguments:
session {.Session} -- The active session for the database connection.
city {String} -- The vehicle's city.
rider_id {UUID} -- The user's unique ID.
rider_city {String} -- The city in which the rider is registered.
vehicle_id {UUID} -- The vehicle's unique ID.
"""
v = session.query(Vehicle).filter(Vehicle.id == vehicle_id).first()
r = Ride(city=city,
id=str(uuid.uuid4()),
rider_id=rider_id,
vehicle_id=vehicle_id,
start_location=v.last_location,
start_time=datetime.datetime.now(datetime.timezone.utc))
session.add(r)
v.status = "unavailable"