"NameError: name 'filename' is not defined" : # Build mongoimport command

    collection = filename[:filename.find('.')]  
    working_directory = 'C:/Users/Anshuman Misra/Downloads/'  
    json_file = filename + '.json'

    mongoimport_cmd = 'mongoimport -h 127.0.0.1:27017 ' + \
                      '--db ' + db_name + \
                      ' --collection ' + collection + \
                      ' --file ' + working_directory + json_file

# Before importing, drop collection if it exists (i.e. a re-run)

    if collection in db.collection_names():  
        print 'Dropping collection: ' + collection
        db[collection].drop()

# Execute the command

    print 'Executing: ' + mongoimport_cmd  
    subprocess.call(mongoimport_cmd.split())