Event hooks

Pass EventHooks to Client to inspect or modify requests and responses. Callbacks are synchronous and run in list order for every request/response exchange, including each followed redirect.

def __init__(
    out self, *,
    request: List[RequestHook] = List[RequestHook](),
    response: List[ResponseHook] = List[ResponseHook](),
)

RequestHook(handler: def(mut Request) raises HTTPError -> None)
ResponseHook(handler: def(mut Response) raises HTTPError -> None)

import req


def before_request(mut request: req.Request) raises req.HTTPError:
    request.headers.set("X-Application", "example")


def after_response(mut response: req.Response) raises req.HTTPError:
    response.raise_for_status()


def main() raises:
    var owner = req.Client(event_hooks=req.EventHooks(
        request=[req.RequestHook(before_request)],
        response=[req.ResponseHook(after_response)],
    ))
    with owner.context() as client:
        var response = client.get("https://example.com")
        print(response.status_code)

Request hooks receive the prepared request after defaults, authentication, and cookies are applied. Mutated requests are validated before dispatch. A request-hook error prevents sending and stops later hooks.

Response hooks receive the response before its body is automatically buffered. Call response.read() before accessing text() or json() in a hook. A response-hook error closes the response stream and stops later hooks. Transport failures do not invoke response hooks.

The hook lists are copied when configuring Client. The owning client exposes event_hooks: EventHooks; its lists can also be updated for later exchanges.