Fix error due to incorrect access of location in callback in drone_delivery

Author: hamishwillee

docs/examples/drone_delivery.rst

@@ -63,28 +63,17 @@ On the command prompt you should see (something like):
 
 .. code-block:: bash
 
-    \dronekit-python\examples\drone_delivery>drone_delivery.py
-    local path: E:\deleteme\dronekit-python\examples\drone_delivery
     Connecting to vehicle on: 127.0.0.1:14550
-    >>> ☺APM:Copter V3.4-dev (e0810c2e)
-    >>> ☺Frame: QUAD
-    connected ...
+    >>> Frame: QUAD
+    [DEBUG]: Connected to vehicle.
     [DEBUG]: DroneDelivery Start
-    [DEBUG]: Waiting for GPS Lock
-    [DEBUG]: DroneDelivery Armed Callback
-    [DEBUG]: GPS: GPSInfo:fix=3,num_sat=10
+    [DEBUG]: Waiting for ability to arm...
     [DEBUG]: Running initial boot sequence
-    [DEBUG]: Arming
+    [DEBUG]: Changing to mode: GUIDED
+    [DEBUG]: Waiting for arming...
     [DEBUG]: Taking off
-    [DEBUG]: Mode: GUIDED
-    INFO:cherrypy.error:[21/Oct/2015:16:33:15] ENGINE Bus STARTING
-    INFO:cherrypy.error:[21/Oct/2015:16:33:15] ENGINE Started monitor thread 'Autoreloader'.
-    INFO:cherrypy.error:[21/Oct/2015:16:33:15] ENGINE Started monitor thread '_TimeoutMonitor'.
-    INFO:cherrypy.error:[21/Oct/2015:16:33:15] ENGINE Serving on http://0.0.0.0:8080
-    INFO:cherrypy.error:[21/Oct/2015:16:33:15] ENGINE Bus STARTED
-    >>> ☺ARMING MOTORS
-    >>> ☺Initialising APM...
-    ...
+    http://localhost:8080/
+    [DEBUG]: Goto: [u'-35.4', u'149.2'], 29.98
     
 
 Screenshots
@@ -110,21 +99,24 @@ For instance, `drone_delivery.py <https://github.com/dronekit/dronekit-python/bl
 
 .. code-block:: python
 
-    self.vehicle.add_attribute_observer('location', self.location_callback)
+    self.vehicle.add_attribute_listener('location', self.location_callback)
 
     ...
 
-    def location_callback(self, location):
-        location = location.global_frame
-
-        if location.alt is not None:
-            self.altitude = location.alt
+    def location_callback(self, vehicle, name, location):
+        if location.global_relative_frame.alt is not None:
+            self.altitude = location.global_relative_frame.alt
 
-        self.current_location = location
+        self.current_location = location.global_relative_frame
 
 
 This results in DroneKit calling our ``location_callback`` method any time the location attribute gets changed.
 
+.. tip:: 
+
+    It is also possible (and often more elegant) to add listeners using a decorator 
+    - see :py:func:`Vehicle.on_attribute <dronekit.Vehicle.on_attribute>`.
+
 
 
 Starting CherryPy from a DroneKit application

examples/drone_delivery/drone_delivery.py

@@ -10,7 +10,7 @@
 import simplejson
 import time
 from pymavlink import mavutil
-from dronekit import connect, VehicleMode, LocationGlobal
+from dronekit import connect, VehicleMode, LocationGlobal, LocationGlobalRelative
 import cherrypy
 from cherrypy.process import wspbus, plugins
 from jinja2 import Environment, FileSystemLoader
@@ -130,9 +130,9 @@ def get_location(self):
 
     def location_callback(self, vehicle, name, location):
         if location.global_relative_frame.alt is not None:
-            self.altitude = location.alt
+            self.altitude = location.global_relative_frame.alt
 
-        self.current_location = location
+        self.current_location = location.global_relative_frame
 
     def _log(self, message):
         print "[DEBUG]: {0}".format(message)