Set extra record cause "KeyError" issue in FastAPI

When i set some extra record in fastAPI startup event caused something error

Versions:

• python 3.8.12
• loguru 0.6.0
• fastapi 0.75

---

Code:

def logger_init():
    logger.remove()
    logger.add(
        sys.stdout,
        format="{extra[event]}",
    )
   context_logger = logger.bind(event="access")
   return context_logger

app = FastAPI()
@app.on_event("startup")
async def startup_event():
    logger = logger_init()
    logger.info("Start up")
       

---

Error message :

--- Logging error in Loguru Handler #1 ---
Record was: {'elapsed': datetime.timedelta(microseconds=270683), 'exception': None, 'extra': {}, 'file': (name='__init__.py', path='/app/./app/__init__.py'), 'function': 'startup_event', 'level': (name='INFO', no=20, icon='ℹ️'), 'line': 100, 'message': '--- Startup Event ---', 'module': '__init__', 'name': 'app', 'process': (id=229, name='SpawnProcess-102'), 'thread': (id=139944207652672, name='MainThread'), 'time': datetime(2022, 7, 6, 14, 51, 4, 487669, tzinfo=datetime.timezone(datetime.timedelta(0), 'UTC'))}
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/loguru/_handler.py", line 155, in emit
    formatted = precomputed_format.format_map(formatter_record)
KeyError: 'event'
--- End of logging error ---

[Delgan]

@GGGoingdown Thanks for the fully reproducible example.

The provider value is only present in the logger object returned by .bind(). The extra dict of default logger is empty, which causes a KeyError during formatting. You can set a default value with logger.configure(extra={"provider": None}) for example.

[Delgan]

Use the patch() function then:

logger.patch(lambda record: record.update(event="login")).debug("Example message!")