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pythonasync-awaitpython-asynciopython-3.6

python3 -Get result from async method


I have written a simple scraping program using asyncio. Here are my code snippets:

loop = asyncio.get_event_loop()
task = loop.create_task(conSpi.parse(arguments.url))
value = loop.run_until_complete(asyncio.wait([task]))
loop.close()

I want to print the result being returned in value. Rather than printing the variable's value, it prints something like this:

{<Task finished coro=<ConcurrentSpider.parse() done, 
 defined at /home/afraz/PycharmProjects/the-lab/concurrentspider.py:28> result=3>}

How can I get the result only and not get rest printed?


Solution

  • The simplest approach is to write

    value = loop.run_until_complete(task)
    

    That only works if you want to wait on one task. If you need more than one task, you'll need to use asyncio.wait correctly. It returns a tuple containing completed and pending futures. By default though, the pending futures will be empty because it waits for all futures to complete.

    So something like

    done, pending = loop.run_until_complete(asyncio.wait( tasks))
    for future in done:
        value = future.result() #may raise an exception if coroutine failed
        # do something with value