weather["temp_c"] results in KeyError: 'temp_c' #28
Description
Every couple of weeks my display goes blank which leads me to turning my pi off and on again to get it going again. I finally made the time to look into the issue when it cropped up again this morning:
The log ends with the following:
File "/home/pi/its-a-plane-python/scenes/weather.py", line 111, in grab_current_temperature
current_temp = weather["temp_c"]
KeyError: 'temp_c'
In weather.py, grab_weather() loads data in a try block, but I suspect that urllib.request.urlopen() sometimes loads a string which does not contain weather data (eg if there's a server error which returns an error string when an API call is attempted). Therefore it is possible to load invalid data without raising an exception.
My first attempt at solving the problem simply involves referencing the "temp_c" key within the try block:
@lru_cache()
def grab_weather(location, ttl_hash=None):
del ttl_hash # not used directly, just part of the cache key
content = None
retries = WEATHER_RETRIES
while retries:
try:
request = urllib.request.Request(WEATHER_API_URL + location)
raw_data = urllib.request.urlopen(request, timeout=3).read()
content = json.loads(raw_data.decode("utf-8"))
content["temp_c"] # checking if the retrieved data is valid
break
except Exception as e:
retries -= 1
else:
# We've ran out of retries without getting new weather data
raise WeatherError(
f"Failed to fetch weather data for '{location}' after {WEATHER_RETRIES} retries"
)
return content
My expectation is that this will raise an exception if weather data is not received (which will then trigger a retry). I'll see how it goes in the next few weeks and give feedback.