Context Variables

The middleware provides two contextvars.ContextVar instances for request-scoped storage. These variables make the correlation ID and user ID available throughout the application — including code that does not have access to Falcon's req object, such as logging filters, utility functions, and downstream service clients.

A context variable for the current request's correlation ID.

• Type: contextvars.ContextVar[str | None]
• Default: None

from falcon_correlate import correlation_id_var

# Retrieve the current correlation ID (None if not set)
cid = correlation_id_var.get()

A context variable for the current request's authenticated user ID.

• Type: contextvars.ContextVar[str | None]
• Default: None

from falcon_correlate import user_id_var

# Retrieve the current user ID (None if not set)
uid = user_id_var.get()

Note: correlation_id_var lifecycle is managed automatically by the middleware. It is set during process_request and reset during process_response, including request-failure paths. The user_id_var is intended for use by authentication middleware or application code that identifies the current user.