CODEWITHSUNDEEP
pythonpython-asynciocoroutineiterable
Forna
Forna

Reputation: 111

'yield from' alternative for async def function

In a class that is almost 100% async I need to execute some code (that is currently a coroutine) in a synchronous (sequential) way. So I created this function:

@asyncio.coroutine
def execute_sequential(self, doo):
    for key in doo:
        yield from self.fetch_one_fin_instr_hist_data(doo[key])

That I execute it with these commands:

tasks = [self.execute_sequential(doo)]
await asyncio.gather(*tasks)

The fetch_one_fin_instr_hist_data must be a coroutine since it is called by an async function. It has the following signature:

async def fetch_one_fin_instr_hist_data(self, obj):

Everything works fine. Unfortunately the @asyncio.coroutine is deprecated, so I should replace it with the async def keywords. The yield from is not supported by async def.

I have tried the following:

async def execute_sequential(self, doo):
    for key in doo:
        for obj in self.fetch_one_fin_instr_hist_data(doo[key]):
            yield obj

but at the line

for obj in self.fetch_one_fin_instr_hist_data(doo[key]):

I get the error:

Expected type 'collections.Iterable', got 'Coroutine[Any, Any, None]' instead

Is there a way to convert a coroutine to an iterable? Or better, what could be an alternative for yield from in this case?

Upvotes: 2

Views: 1723

Answers (2)

dirn
dirn

Reputation: 20729

While yield from is still valid for creating a generator, this particular has been replaced by the await keyword.

@asyncio.coroutine
def execute_sequential(self, doo):
    for key in doo:
        yield from self.fetch_one_fin_instr_hist_data(doo[key])

should now be

async def execute_sequential(self, doo):
    for key in doo:
        await self.fetch_one_fin_instr_hist_data(doo[key])

Upvotes: 2

Cow
Cow

Reputation: 3030

As mentioned in the comments by dirn, yield was replaced with await:

async def execute_sequential(self, doo):
    for key in doo:
        for obj in self.fetch_one_fin_instr_hist_data(doo[key]):
            await obj

Upvotes: 0

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