Why in async iterator give errror: RuntimeError: Task got bad yield: 1

Question

I am new in Asynchronous Python. I study the behavior of asynchronous iterators. I do everything as written by pep492. But get it RuntimeError: Task got bad yield: 1. Help please understand what i do wrong. On this site, I read about this error but did not understand anything

class Awaitable:
    def __await__(self):
        i = 1
        while i < 3:
            yield i
            print("yield {}".format(i))
            i +=1
        return i

class AsyncIterator:

    def __aiter__(self):
        return self

    async def __anext__(self):
        try:
            value = await Awaitable()
        except StopIteration:
            raise StopAsyncIteration
        return value

i = AsyncIterator().__aiter__()

async def coro():
    while True:
        try:
            row = await i.__anext__()
            print(row)
        except StopAsyncIteration:
            break
        else:
            print(row)

event_loop = asyncio.get_event_loop()
event_loop.run_until_complete(coro())
.............................................................
  File "C:\Users\mykola\Downloads\async_await.py", line 342, in __await__
    yield i
RuntimeError: Task got bad yield: 1

Possible duplicate of [Python asyncio task got bad yield](https://stackoverflow.com/q/30172821/213550) — VMAtm, Mar 18 '18 at 15:58
unfortunately I do not understand what is being written in these sources that you offered to read. I'm doing everything as it is written in pep-492. In __anext__ corotine after await is Awaitable() object, its method __await__ returns an iterator as it is written pep-492. Сould you fix my code? Maybe then it will become clearer to me — Mykola Fenyk, Mar 22 '18 at 15:32
Basically, you cannot return a value from async function - you need to return a promise — VMAtm, Mar 22 '18 at 15:39
It is a TypeError if __await__ returns anything but an iterator. — Mykola Fenyk, Mar 24 '18 at 21:03

Why in async iterator give errror: RuntimeError: Task got bad yield: 1

0 Answers0