tutorial-maproutelistener.md

Device Map Route Listener

In this tutorial you'll create device that listens to a command to calculates an prints the instructions for a map route.

[todo] image needed

Prerequisites

[todo]

Create a map listener for IoT Hub

1. From Visual Studio Code, create a new file called c2dmaproutelistener.py.

2. Copy and paste the following import statements into your c2dmaproutelistener.py file

   import os
   import time
   import json
   import asyncio
   from azure.core.credentials import AzureKeyCredential
   from azure.maps.route import MapsRouteClient
   from maproute import createRouteList, printEVRoute, printEVRouteGuidance
   from azure.iot.device.aio import IoTHubDeviceClient

3. Copy and paste the following event handler after your import statements

   def message_handler(message):
       print("Message Received")
       mapkey = ''
       maptype = ''
       currentChargePercent = 0.0
       data = []
   
       # print data from both system and application (custom) properties
       for property in vars(message).items():
           if property[0] == 'custom_properties':
               for cprops in property[1].items():
                   if cprops[0] == 'key':
                       mapkey = cprops[1]
                       print("\tkey={0}".format(mapkey))
                   elif cprops[0] == 'currentChargePercent':
                       currentChargePercent = float(cprops[1]) * 0.01
                       print("\tcurrentChargePercent={0}".format(currentChargePercent*100))
                   elif cprops[0] == 'maxChargekWh':
                       maxChargekWh = float(cprops[1])
                       print("\tmaxChargekWh={0}".format(maxChargekWh))
                   elif cprops[0] == 'maptype':
                       maptype = cprops[1]
                       print("\tmaptype={0}".format(maptype))
           elif property[0] == "data":
               data = json.loads(property[1])
               print("\tdata={0}".format(data)) 
       
       if(maptype == 'guidance'):
           if(len(mapkey) > 1):
               if(len(data) > 1):
                   printEVRouteGuidance(mapkey,createRouteList(data),'',currentChargePercent,maxChargekWh)
       elif(maptype == 'route'):
           if(len(mapkey) > 1):
               if(len(data) > 1):
                   printEVRoute(mapkey,createRouteList(data),'',currentChargePercent,maxChargekWh)
       else:
           print('unknown map type, choose \"route\" or \"guidance\"')

4. Copy and paste the following main function after your event handler.

   async def main():
       client = IoTHubDeviceClient.create_from_connection_string(os.getenv("IOTHUB_DEVICE_CONNECTION_STRING"))
   
       print ("...waiting for C2D messages, press Ctrl-C to exit.")
       try:
           # Attach the handler to the client
           client.on_message_received = message_handler
   
           while True:
               time.sleep(1000)
       except KeyboardInterrupt:
           print("IoT Hub C2D Messaging device sample stopped")
       finally:
           # Graceful exit
           print("Shutting down IoT Hub Client")
           client.shutdown()
   
   if __name__ == "__main__":
       asyncio.run(main())