Feed list

gistfile1.pytb

Unhandled Error
Traceback (most recent call last):
  File "sscce.py", line 32, in <module>
    reactor.run()
  File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1162, in run
    self.mainLoop()
  File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1171, in mainLoop
    self.runUntilCurrent()
--- <exception caught here> ---
  File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 766, in runUntilCurrent
    f(*a, **kw)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 360, in callback
    assert not isinstance(result, Deferred)
exceptions.AssertionError: 

sscce.py

# Objective: get a list of feeds from a database and print them out.

from twisted.internet import reactor, task, threads
from twisted.enterprise.adbapi import ConnectionPool
from twisted.web.client import Agent

def get_feed_urls(db):
    ''' Returns a list of each feed's url and name'''
    return db.runInteraction(select_url)

def select_url(txn):
    ''' Does db fetch work in thread for get_feed_urls '''
    txn.execute("SELECT url, source FROM feeds")
    return txn.fetchall()

def update(db, agent):
    ''' Get a list of feeds '''
    d = threads.deferToThread(get_feed_urls, db)
    d.addCallback(update_callback, agent)

def update_callback(feed_list, agent):
    ''' Add all new entries in every feed to the database. '''
    print str(feed_list)
    # ...

if __name__ == '__main__':
    db_url = 'test.sqlite'
    db = ConnectionPool('sqlite3', db_url, check_same_thread = False)

    agent = Agent(reactor)
    loopingCall = task.LoopingCall(update, db, agent)
    loopingCall.start(2, False)

    reactor.run()