[TIPS] Python Mixins - LoggingMixin
By khoanc, at: Sept. 7, 2025, 9:22 p.m.
Estimated Reading Time: __READING_TIME__ minutes
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Logging doesn’t have to be messy. Instead of sprinkling print() or logging calls everywhere, you can drop in a LoggingToolkitMixin to give any Python class structured, JSON-ready logs with almost no effort.
The Complete Mixin
import logging, json, datetime, contextvars, time, functools
correlation_id = contextvars.ContextVar("correlation_id", default="-")
class JsonFormatter(logging.Formatter):
def format(self, record):
payload = {
"ts": datetime.datetime.utcfromtimestamp(record.created).isoformat() + "Z",
"level": record.levelname,
"logger": record.name,
"msg": record.getMessage(),
}
fields = getattr(record, "fields", None)
if isinstance(fields, dict):
payload.update(fields)
return json.dumps(payload, ensure_ascii=False)
def configure_logging_json(level="INFO"):
handler = logging.StreamHandler()
handler.setFormatter(JsonFormatter())
root = logging.getLogger()
root.handlers[:] = [handler]
root.setLevel(getattr(logging, level.upper(), logging.INFO))
class LoggingMixin:
@property
def logger(self):
return logging.getLogger(f"{self.__class__.__module__}.{self.__class__.__name__}")
class LoggingToolkitMixin(LoggingMixin):
def log(self, level: int, msg: str, **fields):
fields.setdefault("correlation_id", correlation_id.get())
self.logger.log(level, msg, extra={"fields": fields})
def debug(self, msg: str, **f): self.log(logging.DEBUG, msg, **f)
def info(self, msg: str, **f): self.log(logging.INFO, msg, **f)
def warn(self, msg: str, **f): self.log(logging.WARNING, msg, **f)
def error(self, msg: str, **f): self.log(logging.ERROR, msg, **f)
def is_debug(self) -> bool:
return self.logger.isEnabledFor(logging.DEBUG)
def timed(self, name=None):
def deco(func):
label = name or func.__name__
@functools.wraps(func)
def wrapper(*args, **kwargs):
t0 = time.perf_counter()
try:
return func(*args, **kwargs)
finally:
self.info("timed", op=label, ms=round((time.perf_counter()-t0)*1000, 2))
return wrapper
return deco
# Example usage
class PaymentService(LoggingToolkitMixin):
def charge(self, order_id: str, amount: float):
self.info("charge.start", order_id=order_id, amount=amount)
# ... business logic ...
self.info("charge.success", order_id=order_id)
How to Use It
1. Configure JSON logging once at startup
configure_logging_json("DEBUG")
correlation_id.set("Glinteco-2025")
2. Extend any class with the mixin
service = PaymentService()
service.charge("order-42", 19.99)
3. Get structured, JSON logs like this
{"ts": "2025-09-07T14:30:01Z", "level": "INFO", "logger": "__main__.PaymentService", "msg": "charge.start", "order_id": "order-42", "amount": 19.99, "correlation_id": "glinteco-2025"}
{"ts": "2025-09-07T14:30:01Z", "level": "INFO", "logger": "__main__.PaymentService", "msg": "charge.success", "order_id": "order-42", "correlation_id": "glinteco-2025"}
Why This Works
-
JSON formatter → machine-readable logs for search & monitoring tools
-
Correlation IDs → track requests across async tasks
-
Timing decorator → measure method execution times
-
Reusable Mixin → drop it into any class without boilerplate
