Answer to Homework 2.2 M101P

import sys
import pymongo
from pymongo import Connection
from pymongo.errors import ConnectionFailure
from datetime import datetime

def main():
    try:
        c = Connection(host="localhost",port=27017)

    except ConnectionFailure as e:
        sys.stderr.write("Could no connect to MongoDB: %s" % e)
        sys.exit(1)
    dbh = c["students"]
    assert dbh.connection == c

    users = dbh.grades.find({'type':'homework'}).sort([['student_id',pymongo.ASCENDING],['score',pymongo.ASCENDING]])

    student_id = -1

    for student in users:
        if student_id != student['student_id']:
            student_id = student['student_id']
            dbh.grades.remove({'_id': student['_id']})

if __name__=="__main__":
    main()