Python async AttributeError aexit - python-3.x

Question

I keep getting error AttributeError: __aexit__ on the code below, but I don't really understand why this happens.
My Python version is: 3.6.4 (v3.6.4:d48eceb, Dec 19 2017, 06:04:45) [MSC v.1900 32 bit (Intel)]
import aiohttp
import asyncio
import tqdm
async def fetch_url(session_, url_, timeout_=10):
with aiohttp.Timeout(timeout_):
async with session_.get(url_) as response:
text = await response.text()
print("URL: {} - TEXT: {}".format(url_, len(text)))
return text
async def parse_url(session, url, timeout=10):
# get doc from url
async with await fetch_url(session, url, timeout) as doc:
print("DOC: {}".format(doc, len(doc)))
return doc
async def parse_urls(session, urls, loop):
tasks = [parse_url(session, url) for url in urls]
responses = [await f for f in tqdm.tqdm(asyncio.as_completed(tasks), total = len(tasks))]
return responses
if __name__ == '__main__':
tickers = ['CTXS', 'MSFT', 'AAPL', 'GPRO', 'G', 'INTC', 'SYNC', 'SYNA']
urls = ["https://finance.yahoo.com/quote/{}".format(ticker) for ticker in tickers]
loop = asyncio.get_event_loop()
with aiohttp.ClientSession(loop=loop) as session:
parsed_data = loop.run_until_complete(parse_urls(session, urls, loop))
print(parsed_data)
Error callstack:
C:\Python\Python36\python.exe C:/Users/me/.PyCharmCE2017.3/config/scratches/scratch_4.py
0%| | 0/8 [00:00<?, ?it/s]Traceback (most recent call last):
URL: https://finance.yahoo.com/quote/CTXS - TEXT: 462138
File "C:/Users/me/.PyCharmCE2017.3/config/scratches/scratch_4.py", line 34, in <module>
parsed_data = loop.run_until_complete(parse_urls(session, urls, loop))
File "C:\Python\Python36\lib\asyncio\base_events.py", line 467, in run_until_complete
return future.result()
File "C:/Users/me/.PyCharmCE2017.3/config/scratches/scratch_4.py", line 23, in parse_urls
responses = [await f for f in tqdm.tqdm(asyncio.as_completed(tasks), total = len(tasks))]
File "C:/Users/me/.PyCharmCE2017.3/config/scratches/scratch_4.py", line 23, in <listcomp>
responses = [await f for f in tqdm.tqdm(asyncio.as_completed(tasks), total = len(tasks))]
File "C:\Python\Python36\lib\asyncio\tasks.py", line 458, in _wait_for_one
return f.result() # May raise f.exception().
File "C:/Users/me/.PyCharmCE2017.3/config/scratches/scratch_4.py", line 16, in parse_url
async with await fetch_url(session, url, timeout) as doc:
AttributeError: __aexit__
Process finished with exit code 1

Answer 1

You are trying to use fetch_url as a context manager, but it isn't one. You can either make it one
class fetch_url:
def __init__(self, session, url, timeout=10):
self.session = session
self.url = url
self.timeout = timeout
async def __aenter__(self):
with aiohttp.Timeout(self.timeout):
async with self.session.get(self.url) as response:
text = await response.text()
print("URL: {} - TEXT: {}".format(self.url, len(text)))
return text
async def __aexit__(self, exc_type, exc, tb):
# clean up anything you need to clean up
or change your code to
async def parse_url(session, url, timeout=10):
# get doc from url
doc = await fetch_url(session, url, timeout)
print("DOC: {}".format(doc, len(doc)))
return doc