Weird behavior with external class in django - django

Question

I've got a weird problem here. It hurts my brain thinking about it.
I've got a Django project with multiple apps. Today I added another app.
(views.py)
from %app_name%.%class_file% import %class_name%
def api(request):
t = %class_name%()
data = {}
data['listOtherDevices'] = t.listOtherDevices
logger = logging.getLogger(__name__)
logger.error(len(t.listOtherDevices))
return JsonResponse(data)
The imported class fills the 'listOtherDevices'-array via
__init__ perfectly fine when I run it inside a console. When I do so, there are exactly 3 elements inside this array (as there are 3 devices in my LAN the class could find). So when I visit the url (development server -> manage.py runserver) linked to this method I can see a JSON with exactly 3 entries. So far so good but now comes the weird part. When I refresh the url in my browser or visit it one more time, there are more than 3 entries. The scheme is like this:
opened url 1 time: 3 entries
opened url 2 times: 9 entries (+ 6)
opened url 3 times: 18 entries (+ 9)
opened url 4 times: 30 entries (+ 12)
opened url 5 times: 45 entries (+ 15)
opened url 6 times: 63 entries (+ 18)
I can see a pattern there but I cannot understand why this happends.
sudo sysdig -c spy_users
tells me, that the class is gathering information exactly 3 times using
subprocess.check_output
The responded JSON is syntactically OK. Seems like the class would 'find' 9, or 18 devices.
Please help me, because as I said earlier: this makes my brain hurt :)
import json
import subprocess
class tradfri:
tradfriIPv4 = 'blablabla'
tradfriUser = 'blablabla'
tradfriPassword = 'blablabla'
pathToCoap = '/blablabla/coap-client'
listDevices = []
listGroups = []
listDevicesDetails = []
listGroupsDetails = []
listLightbulbs = []
listOtherDevices = []
def __init__(self):
self.getDevices()
self.getGroups()
self.getArrayLightbulbs()
self.getArrayOtherDevices()
def getDevices(self):
method = 'get'
stdoutdata = subprocess.check_output( self.pathToCoap
+ ' -m ' + method
+ ' -u "' + self.tradfriUser + '"'
+ ' -k "' + self.tradfriPassword + '"'
+ ' coaps://' + self.tradfriIPv4 + ':5684/15001'
+ " | awk 'NR==4'",
shell=True).decode("utf-8")
self.listDevices = json.loads(stdoutdata)
for ID in self.listDevices:
stdoutdata = subprocess.check_output( self.pathToCoap
+ ' -m ' + method
+ ' -u "' + self.tradfriUser + '"'
+ ' -k "' + self.tradfriPassword + '"'
+ ' coaps://' + self.tradfriIPv4 + ':5684/15001/' + str(ID)
+ " | awk 'NR==4'",
shell=True).decode("utf-8")
self.listDevicesDetails.append(json.loads(stdoutdata))
def getGroups(self):
method = 'get'
stdoutdata = subprocess.check_output( self.pathToCoap
+ ' -m ' + method
+ ' -u "' + self.tradfriUser + '"'
+ ' -k "' + self.tradfriPassword + '"'
+ ' coaps://' + self.tradfriIPv4 + ':5684/15004'
+ " | awk 'NR==4'",
shell=True).decode("utf-8")
self.listGroups = json.loads(stdoutdata)
for ID in self.listGroups:
stdoutdata = subprocess.check_output( self.pathToCoap
+ ' -m ' + method
+ ' -u "' + self.tradfriUser + '"'
+ ' -k "' + self.tradfriPassword + '"'
+ ' coaps://' + self.tradfriIPv4 + ':5684/15004/' + str(ID)
+ " | awk 'NR==4'",
shell=True).decode("utf-8")
raw = json.loads(stdoutdata)
tmpMembers = []
for id in raw['9018']['15002']['9003']:
tmpMembers.append( { 'ID': str( id ), 'name': self.getDeviceNameByID(id) } )
self.listGroupsDetails.append( { 'ID': str( raw['9003'] ),
'name': raw['9001'],
'isGroupOn': False,
'members': tmpMembers } )
def getArrayLightbulbs(self):
for item in self.listDevicesDetails:
if item['3']['6'] == 1: # is lightbulb
id = item['9003']
name = item['9001']
groupID = self.getGroupIDByID(id)
groupName = self.getGroupNameByID(id)
manufacturer = item['3']['0']
description = item['3']['1']
isReachable = True
isBulbOn = False
isDimmable = False
isWhiteSpectrum = False
isColorSpectrum = False
brightnessOfBulb = ''
currentColor = ''
#isReachable
if len(item['3311'][0]) == 1:
isReachable = False;
else:
#isBulbOn
if item['3311'][0]['5850'] == 1:
isBulbOn = True
#dimmable & brightnessOfBulb
if '5851' in item['3311'][0]:
brightnessOfBulb = str( item['3311'][0]['5851'] )
isDimmable = True
#currentColor
if '5706' in item['3311'][0]:
currentColor = item['3311'][0]['5706']
#isWhiteSpectrum
if ' WS ' in description:
isWhiteSpectrum = True
#isColorSpectrum
if ' CWS ' in description:
isWhiteSpectrum = True
isColorSpectrum = True
self.listLightbulbs.append( { 'ID': str( id ),
'Name': name,
'groupID': str( groupID ),
'groupName' : groupName,
'manufacturer': manufacturer,
'description' : description,
'isReachable': isReachable,
'isBulbOn': isBulbOn,
'isDimmable': isDimmable,
'isWhiteSpectrum': isWhiteSpectrum,
'isColorSpectrum': isColorSpectrum,
'brightnessOfBulb': brightnessOfBulb,
'currentColor': currentColor } )
def getArrayOtherDevices(self):
for device in self.listDevicesDetails:
if device['3']['6'] == 3:
self.listOtherDevices.append( { 'ID': str( device['9003'] ),
'Name': device['9001'],
'groupID': str( self.getGroupIDByID(str( device['9003']) ) ),
'groupName': self.getGroupNameByID(str( device['9003']) ),
'manufacturer': device['3']['0'],
'description': device['3']['1'] } )
def getDeviceNameByID(self, id):
name = ''
for key in self.listDevicesDetails:
if key['9003'] == id:
name = key['9001']
return name
def getGroupIDByID(self, id):
groupID = ''
for group in self.listGroupsDetails:
for member in group['members']:
if member['ID'] == id:
groupID = group['ID']
return groupID
def getGroupNameByID(self, id):
groupName = ''
for group in self.listGroupsDetails:
for member in group['members']:
if member['ID'] == id:
groupName = group['name']
return groupName

Answer 1

You use class wide attributes to save the data.
Whenever you create a new instance of tradfri your methods work on the same class wide attribute listOtherDevices. Note that the class lives in memory until you restart the server. Therefore the amount of values increases with each request, as you append values to your list.
You should use attributes which are available per instance. In python this is achieved by initializing the attributes inside of __init__(). It might look like that:
class tradfri:
def __init__(self):
self.tradfriIPv4 = 'blablabla'
self.tradfriUser = 'blablabla'
self.tradfriPassword = 'blablabla'
self.pathToCoap = '/blablabla/coap-client'
self.listDevices = []
self.listGroups = []
self.listDevicesDetails = []
self.listGroupsDetails = []
self.listLightbulbs = []
self.listOtherDevices = []
self.getDevices()
self.getGroups()
self.getArrayLightbulbs()
self.getArrayOtherDevices()
Read python class attribute for more details. The official documentation on that topic are also worth reading.