I set up a basic python webserver using BaseHttpServer and am practicing querying data from a postgresql database. Everything is going swimmingly, but I have an error when I'm parsing the SQL results. Here is my code:
cur=con.cursor()
cur.execute(('select * from stop_times as a, stop_times as b where a.train_id=b.train_id and a.station_name = %s and b.station_name= %s and a.arrival_time < b.arrival_time'), (origin_name, dest_name))
self.wfile.write("Train Number     Starting Station     Destination Station     Departure Time     Arrival Time <br />")
while True:
row=cur.fetchone()
if row==None:
break
print row[0], row[1], row[2], row[3], row[4], row[5], row[6], row[7], row[8]
for item in row[0]:
self.wfile.write("%s"% item)
self.wfile.write("                      ")
for item in row[3]:
self.wfile.write("%s"% item)
self.wfile.write("              ")
for item in row[8]:
self.wfile.write("%s"% item)
self.wfile.write("       ")
for item in row[2]:
self.wfile.write("%s"% item)
self.wfile.write("   ")
The print statement is there for debugging to the console, and it gives the correct output:
427 10:23:00 10:23:00 San Antonio 6 427 11:08:00 11:08:00 Millbrae
429 11:23:00 11:23:00 San Antonio 6 429 12:08:00 12:08:00 Millbrae
431 12:23:00 12:23:00 San Antonio 6 431 13:08:00 13:08:00 Millbrae
I'm just trying to output certain columns to the web page, and when I get to that last for loop for row[2] I get this error:
File "./caltrainServer.py", line 129, in performQuery
for item in row[2]:
TypeError: 'datetime.timedelta' object is not iterable
I checked, and those columns in my database are of type interval. How do I iterate through them like I did with my other columns, which were of type varchar?
You are unnecessarily iterating over the contents of the row values. Lines like this:
for item in row[0]:
self.wfile.write("%s"% item)
Could likely be changed to
self.wlfile.write(row[0])
What you are doing, when row[x]
is a string is actually iterating over each letter and writing it. But row[2]
is a datetime.datetime object. And since datetime.datetime objects are not iterable, you get that error message.
Try instead something like:
self.wlfile.write((row[2]))
That places the datetime object in a tuple which can be iterated.