psycopg2 weirdness

[Neha Gupta]

Hey,

I only have little experience with web.py and psycopg2 and am running
into a weird problem, I'd appreciate any help I can get with debugging
it.

I wrote a simple program that works and I don't see any crash:
----
import psycopg2

try:
	database_conn = psycopg2.connect("dbname='dbname' user='username'
host='hostname'");
except:
	print "Unable to connect to the  database!"

database_conn.set_isolation_level(0)
cur = database_conn.cursor();

while True:
    query = "SELECT avg(dep_delay), extract(hour from crs_dep_time) as
crs_dep_hour, origin from flightdata where date = '01-05-2007' group
by origin, crs_dep_hour order by origin, crs_dep_hour";
    cur.execute(query)
    rows = cur.fetchall()
    print rows
-----

However, I have a small website built using web.py framework which has
a date picker that lets the user pick a date and it takes the user to
a new url such as: localhost:8080/departures/01-05-2007. I issue a
query to my database for the date selected by the user and retrieve
the results.  The problem now is that if I select different dates
directly by changing the url then everything works but as soon as I
pick a date from date picker the server crashes. I removed the date
picker and made it just a text box but as soon as I hit the submit
button, server crashes so I know it is not the date picker that
causing trouble.
---
class departures:
	def buildDepartureTableHtml(self, date):
        	web.debug('date', date)
		# Issue the query.
		# select avg(dep_delay), extract(hour from crs_dep_time) as
crs_dep_hour, origin from flightdata where date = '2007-02-15' group
by origin, crs_dep
		# _hour order by origin, crs_dep_hour;
		try:
                      web.debug("About to issue query")
		#	query = "SELECT avg(dep_delay), extract(hour from crs_dep_time) as
crs_dep_hour, origin from flightdata where date = '" + date + "' group
by origin, crs_dep_hour order by origin, crs_dep_hour";
			query = "SELECT avg(dep_delay), extract(hour from crs_dep_time) as
crs_dep_hour, origin from flightdata where date = '01-05-2007' group
by origin, crs_dep_hour order by origin, crs_dep_hour";
			cur.execute(query)
			web.debug('query executed!')
			rows = cur.fetchall()
			web.debug('rows fetched!')
			web.debug(rows)
		except Exception, e:
			print repr(e)
			database_conn.rollback()
			return "<div id='welcome-text'>Invalid Date</div>"
--
// JS code
function submitForm() {
      var date = ($("date").value).replace(/\//g,"-");
     window.location = "http://" + window.location.host + "/
departures/" + date;
}

You can see above that I even ignored the date passed from the form
and I have hardcoded '01-05-2007'. The message "About to issue query"
gets printed as well as the right date chosen from the date picker but
then I see the following:

Assertion failed: (str != NULL), function PyString_FromString, file
Objects/stringobject.c, line 107.
Abort trap

with a pop that says: "The application Python quit unexpectedly. The
problem may have been caused by the _psycopg.so plug-in".
--
I don't understand the error message above. The date did get passed
correctly and am now not even using it, I use the hard coded date. So
what is going on?

Any help would be great.

Thank you!
Neha