Middlewares¶

drf-commons includes middleware for request context management and development debugging.

CurrentUserMiddleware¶

from drf_commons.middlewares import CurrentUserMiddleware

The most important middleware in drf-commons. Sets the authenticated request user into a ContextVar for the duration of each request, enabling automatic audit field population at the model layer without serializer context threading.

Configuration:

MIDDLEWARE = [
    "django.middleware.security.SecurityMiddleware",
    "django.contrib.sessions.middleware.SessionMiddleware",
    "django.middleware.common.CommonMiddleware",
    "django.contrib.auth.middleware.AuthenticationMiddleware",
    # Must come after AuthenticationMiddleware:
    "drf_commons.middlewares.CurrentUserMiddleware",
    ...
]

Async support:

CurrentUserMiddleware detects whether the handler is a coroutine function and dispatches to the appropriate sync or async implementation:

# Sync handler path (WSGI)
def __call__(self, request):
    token = _set_current_user(request.user)
    try:
        response = self.get_response(request)
    finally:
        _reset_current_user(token)
    return response

# Async handler path (ASGI)
async def __acall__(self, request):
    token = _set_current_user(request.user)
    try:
        response = await self.get_response(request)
    finally:
        _reset_current_user(token)
    return response

The finally block guarantees the context is always reset, even if the handler raises an exception. The reset token pattern (rather than ContextVar.set(None)) ensures that nested middleware chains maintain correct context state.

Context API:

from drf_commons.current_user import get_current_user, get_current_authenticated_user

# Get user (may be anonymous)
user = get_current_user()           # Returns User or AnonymousUser or None

# Get authenticated user only
user = get_current_authenticated_user()  # Returns User, raises if not authenticated

Debug Middlewares¶

Debug middlewares are intended for development environments only. Do not enable them in production — they add significant overhead.

DebugMiddleware¶

from drf_commons.middlewares import DebugMiddleware

Base debug middleware. Tracks request context and timing metadata. Parent class for the specialized debug middlewares.

SQLDebugMiddleware¶

from drf_commons.middlewares import SQLDebugMiddleware

Captures all SQL queries executed during a request and logs:

Total query count
Individual query durations
Slow queries (above DEBUG_SLOW_QUERY_THRESHOLD)
Alerts when query count exceeds DEBUG_HIGH_QUERY_COUNT_THRESHOLD

Configuration:

COMMON = {
    "DEBUG_SLOW_QUERY_THRESHOLD": 0.1,          # seconds per query
    "DEBUG_HIGH_QUERY_COUNT_THRESHOLD": 10,     # query count alert
}

Development setup:

# settings/development.py
if DEBUG:
    MIDDLEWARE += [
        "drf_commons.middlewares.SQLDebugMiddleware",
    ]

ProfilerMiddleware¶

from drf_commons.middlewares import ProfilerMiddleware

Profiles request handler execution using Python’s cProfile. Logs function call statistics for slow requests (above DEBUG_SLOW_REQUEST_THRESHOLD).

COMMON = {
    "DEBUG_SLOW_REQUEST_THRESHOLD": 1.0,  # seconds; log profiling data above this
}

Development setup:

if DEBUG:
    MIDDLEWARE += [
        "drf_commons.middlewares.ProfilerMiddleware",
    ]

Middleware Order Reference¶

Recommended middleware order for a project using all drf-commons middleware:

MIDDLEWARE = [
    "django.middleware.security.SecurityMiddleware",
    "whitenoise.middleware.WhiteNoiseMiddleware",       # if using whitenoise
    "django.contrib.sessions.middleware.SessionMiddleware",
    "django.middleware.common.CommonMiddleware",
    "django.middleware.csrf.CsrfViewMiddleware",
    "django.contrib.auth.middleware.AuthenticationMiddleware",
    "drf_commons.middlewares.CurrentUserMiddleware",   # after auth
    "django.contrib.messages.middleware.MessageMiddleware",
    "django.middleware.clickjacking.XFrameOptionsMiddleware",
]

# Development only:
if DEBUG:
    MIDDLEWARE += [
        "drf_commons.middlewares.SQLDebugMiddleware",
        "drf_commons.middlewares.ProfilerMiddleware",
    ]