How to await method in loop?

I have the following method that generates data for me:

async def generate_url(self, video_id):
    data = await self.s3.generate_presigned_url(...video_id...)
    return data

def convert_to_json(self, urls):
    ids = [self.generate_url(url) for url in urls]
    ...

How to correctly await generate_url in convert_to_json?

You may use a wait wrapper around the list of tasks:

async def convert_to_json(self, urls):
    tasks = [self.generate_url(url) for url in urls]
    await asyncio.wait(tasks)

Or, if you can't mark convert_to_json method as async, wait it synchronously:

import asyncio

def convert_to_json(self, urls):
    loop = asyncio.get_event_loop()
    tasks = [self.generate_url(url) for url in urls]
    loop.run_until_complete(asyncio.wait(tasks))

Also you can try to implement an async iterator and use it with async for syntax, something like this:

class Loader:
    def __init__(self, urls):
        self._urls = iter(urls)

    async def generate_url(self, video_id):
        data = await self.s3.generate_presigned_url(...video_id...)
        return data

    def __aiter__(self):
        return self

    async def __anext__(self):
        try:
            url = next(self._urls)
        except StopIteration:
            raise StopAsyncIteration
        data = await self.generate_url(url)
        return data

async for id in Loader(urls):
    print(id)