tps_vehiclepos_load_pushpinLabels_from_dynamodb.py

#read the contents ot pushpinLabelsTable and populate pushpinLabels_LabelNum and pushpinLabels_Label dict
def load_pushpinLabels_from_dynamodb(today):
  global dict_pushpinLabel_to_desc_map
  global dict_vehicleId_to_pushpinLabel_map
  global lastpushpinLabel

  rdate = today.strftime("%Y-%m-%d")
  pushpinLabelsTableContents = pushpinLabelsTable.query(
             IndexName='TripDate-GSI',
             KeyConditionExpression='TripDate = :tripdate',
             ExpressionAttributeValues={":tripdate":rdate}
           )
  
  #check to see if there were any items returned from the above query 
  if len(pushpinLabelsTableContents['Items']) > 0:
    #there were some items returned
    #the vehicle's label could be same across different vehicles however its id is unique for the day. For this reason
    #we must store the vehicle id along with the pushpinLabel and pushpinLabelDesc
    for item in pushpinLabelsTableContents['Items']:
      pushpinLabel = item['pushpinLabel']
      pushpinLabelDesc = item['pushpinLabelDesc']
      vehicleId = item['VehicleId']
      inDynamodbTable = True  #we will mark all entries that are being populated from dynamodb, so that when we update dynamodb
                              #we only write items that are missing, not everything. This saves on write capacity units
      #the following fields were added progressively to dynamodb. Ensure that missing items doesn't break the code. Just add blanks if missing
      try:
        latitude = item['latitude']
      except:
        latitude = ""
      try:
        longitude = item['longitude']
      except:
        longitude = ""
      try:
        tripId = item['tripId']
      except:
        tripId = ""

      dict_pushpinLabel_to_desc_map[str(pushpinLabel)] = {"desc": str(pushpinLabelDesc), "vehicleId": str(vehicleId), "inDynamodbTable": inDynamodbTable, "latitude": latitude, "longitude": longitude, "tripId": tripId}
      dict_vehicleId_to_pushpinLabel_map[str(vehicleId)] = {"label": str(pushpinLabel), "desc": str(pushpinLabelDesc)}      

      #if a higher pushpinLabel was found in pushpinLabels table, then set the lastPushpinLabel to this
      if int(pushpinLabel) > int(lastpushpinLabel):
        lastpushpinLabel = int(pushpinLabel)  
  #else there were no results for the above query, which means there were no entries in dynamodb table for today. Let's start fresh
  print("load_pushpinLabels_from_dynamodb: Loaded ", len(pushpinLabelsTableContents['Items']), "pushpinLabels from dynamodb table. lastpushpinLabel:", lastpushpinLabel)