CODEWITHSUNDEEP
pythonlistgoogle-app-enginegoogle-mapsexception
Franz Noel
Franz Noel

Reputation: 1880

List IndexError out of range in GAE

This geocoding code works locally, but not in the server, it gets the address in the form of self.request.get('address') and returns the ndb.GeoPt() value from a get_lat_long(address) function.

So, how come I get the error: 

Traceback (most recent call last):
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1535, in __call__
    rv = self.handle_exception(request, response, e)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1529, in __call__
    rv = self.router.dispatch(request, response)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1278, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1102, in __call__
    return handler.dispatch()
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 572, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 570, in dispatch
    return method(*args, **kwargs)
  File "/base/data/home/apps/s~map-jobs/2.371278632227250958/main.py", line 453, in post
    profile.geopoint = get_lat_long(self.request.get('address'))
  File "/base/data/home/apps/s~map-jobs/2.371278632227250958/main.py", line 17, in get_lat_long
    lat = data['results'][0]['geometry']['location']['lat']
IndexError: list index out of range

With this code: 

def get_lat_long(address):
  address = cgi.escape(address.replace(" ","+"))
  sensor = "true"
  url = "http://maps.googleapis.com/maps/api/geocode/json?address=" + address + "&sensor="+ sensor
  result = urlfetch.fetch(url)
  data = json.loads(result.content)
  lat = data['results'][0]['geometry']['location']['lat']
  long = data['results'][0]['geometry']['location']['lng']
  return ndb.GeoPt(str(lat) +","+ str(long))

What is the correct way of writing this in the google-app-engine server?

Upvotes: 0

Views: 555

Answers (2)

Nilesh
Nilesh

Reputation: 2555

You can use len() to check index existence.

Upvotes: 1

Nafiul Islam
Nafiul Islam

Reputation: 82470

data['results'][0] is actually empty.

This happens when there are not results. Usually, I just put it in a try/catch block, and except an IndexError:

try:
    data['results'][0]....
except IndexError, e:
    print "No data found"  # You can use a logger here too

In your case, put a try/catch block around the following code, and find a way to deal with the error:

  lat = data['results'][0]['geometry']['location']['lat']
  long = data['results'][0]['geometry']['location']['lng']

This happened to me a lot, when I was working with google drive, since a lot of the doucments did not have text/html as an output format, I was always getting KeyError. In your case you are dealing with google maps, and if there are results there should be geometry and the other keys in the dict, however, you may also choose to add KeyError to your except clause to be extra precautious.

Upvotes: 1

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