Setting Cookies Early with aiohttp Requests

Feb 22, 2024 ยท 2 min read

When making requests with the Python aiohttp library, it's best practice to set any needed cookies on the session before sending your first request. This ensures the cookies are properly included in all requests made with that session.

Here is a code snippet showing how to set a cookie on an aiohttp ClientSession before making a request:

import aiohttp

async with aiohttp.ClientSession() as session:
    session.cookie_jar.update_cookies({'user': 'john'})
    async with session.get('') as resp:
        print(await resp.text())

By updating the cookie jar directly, we set the user=john cookie on the session. This cookie will then automatically be included in any requests made with session, like our GET to

Why Set Cookies Early?

Many websites require cookies to maintain user sessions. If you don't set needed session cookies upfront, your first request may be rejected or redirected to a login page. Subsequent requests would then succeed, but the first one fails.

By setting cookies first, you ensure all requests have the expected context and cookies from the start. This prevents unexpected login pages or errors.

Alternatives to Setting Cookies

If you need dynamic cookie values that change over time, setting them upfront may not work. Some options in this case:

  • Make an initial request to get any required cookies, then make your real requests
  • Extract cookie values from responses and set them before subsequent requests
  • Use an abstract cookie session class that handles cookies behind the scenes
  • The key is making sure each request has the cookies it needs, whether by setting them early or handling them dynamically.

    I hope these tips help you effectively use cookies with aiohttp!

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