Average speed based on time and distance - Python - python-3.x

Question

I'm tryng to figure out how I can fix my problem here, but it keeps failing.
So I currently have this code:
#staticmethod
def avg_speed():
# Speed = Distance ÷ Time
cur_time = datetime.datetime.now().replace(microsecond=0)
db_time_record = DB().start_time()
time_diff = cur_time - db_time_record
# print(str(time_diff).split(":"))
total_distance = DB().get_total_distance()
result = (total_distance / (float(time_diff.total_seconds()))) * 60
return round(result, 2)
But the thing is, the average speed is so high, it is not possible that the speed is correct.... Now, what the DB() record has a MySQL DATETIME object.
That looks like: datetime.now().strftime("%Y-%m-%d %H:%M:%S") (2017-08-22 15:28:19)
Now what I want, as stated in the code, is the average speed based on the distance traveled and the time. The distance is in meters and the time should be in seconds?
What am I doing wrong here?

Answer 1

I don't have a MySQL database available to test your code, but if you can read the start_time from the DB as a string in the format like "2017-08-22 15:28:19" then the following example shows how to do a speed calculation:
import datetime
# (simulate reading time from database as string)
time_string_from_db = "2017-08-22 15:28:19"
dbtime = datetime.datetime.strptime(time_string_from_db, "%Y-%m-%d %H:%M:%S")
cur_time = datetime.datetime.now().replace(microsecond=0)
print ("dbtime: " + repr(dbtime))
print ("cur_time: " + repr(cur_time))
elapsed = cur_time - dbtime
seconds = elapsed.total_seconds()
print ("elapsed: " + repr(elapsed))
print ("seconds: " + repr(seconds))
distance = 500
speed = distance / seconds
print ("speed: " + repr(speed))
Hope some of this may be useful.