def queryPossible(self):
'''Check from the database if we even have the requested number of devices to service the query.'''
#if found return True
#To Write a SELECT query when DB Schema finalized.
#assuming no future queries for now
#Untested code
if self.queryDBObject.frequency==0:
u=Sensor.select().where((str(self.queryObject['dataReqd'])== Sensor.SensorType)).distinct()
else:
u=Sensor.select().where((str(self.queryObject['dataReqd'])== Sensor.SensorType)&((Sensor.minDelay==0)|(eval(str(self.queryObject['frequency']))<1000000.0/Sensor.minDelay)) ).distinct()
z = User.select().join(SensorUserRel).where(SensorUserRel.sensor << u).distinct()
''' Possible query to get all users of such sensors in u:
z = User.select().join(SensorUserRel).where(SensorUserRel.sensor << u).distinct()
'''
lat1 = self.queryDBObject.Latitude
lon1 = self.queryDBObject.Longitude
if self.queryDBObject.Radius<0 or lat1<0 or lon1<0:
''' Radius to not be considered! '''
for i in z:
self.providerList += [i]
else:
R = self.queryDBObject.Radius
for i in z:
if self.getDistanceInKM(lon1, lat1, i.Longitude, i.Latitude) <= R:
self.providerList += [i]
print 'Found count=' + str(len(self.providerList)) + ' for query Number: ' + self.queryNo
if(len(self.providerList)>=eval(str(self.queryObject['countMin']))):
#Query is possible; initiate messages to valid subscribers to respond with an acknowledgement.
return True
else:
return False
