Python async generators and async iteration

Need to produce values asynchronously, like streaming API responses or paginated database results.

Async generators yield values from async operations:

import asyncio
import aiohttp

# Async generator for paginated API
async def fetch_all_pages(url):
    async with aiohttp.ClientSession() as session:
        next_url = url
        while next_url:
            async with session.get(next_url) as resp:
                data = await resp.json()
                for item in data['results']:
                    yield item
                next_url = data.get('next')

# Async generator for streaming lines
async def stream_lines(reader):
    async for line in reader:
        stripped = line.decode().strip()
        if stripped:
            yield stripped

# Consuming async generators
async def main():
    # async for loop
    async for user in fetch_all_pages('/api/users'):
        print(user['name'])

    # Collect into list
    users = [u async for u in fetch_all_pages('/api/users')]

    # First N items
    count = 0
    async for item in fetch_all_pages('/api/items'):
        process(item)
        count += 1
        if count >= 100:
            break

asyncio.run(main())

Async generators combine lazy evaluation with async I/O, enabling memory-efficient processing of large datasets from async sources.

Python async code processing streams or paginated data