Django DoesNotExist

Question

I am having issues on trying to figure "DoesNotExist Errors", I have tried to find the right way for manage the no answer results, however I continue having issues on "DoesNotExist" or "Object hast not Attribute DoestNotExists"

from django.http import HttpResponse
from django.contrib.sites.models import Site
from django.utils import simplejson

from vehicles.models import *
from gpstracking.models import *


def request_statuses(request):

    data = []
    vehicles = Vehicle.objects.filter()
    Vehicle.vehicledevice_
    for vehicle in vehicles:
        try:
            vehicledevice = vehicle.vehicledevice_set.get(is_joined__exact = True)
            imei = vehicledevice.device.imei
            try:
                lastposition = vehicledevice.device.devicetrack_set.latest('date_time_process')
                altitude = lastposition.altitude
                latitude = lastposition.latitude
                longitude =  lastposition.longitude
                date_time_process = lastposition.date_time_process.strftime("%Y-%m-%d %H:%M:%S"),
                date_time_created = lastposition.created.strftime("%Y-%m-%d %H:%M:%S")
            except Vehicle.vehicledevice.device.DoesNotExist:
                lastposition = None
                altitude = None
                latitude = None
                longitude = None
                date_time_process = None
                date_time_created = None
        except Vehicle.DoesNotExist:
            vehicledevice = None
            imei = ''

        item = [
                vehicle.vehicle_type.name,
                imei,
                altitude,
                "Lat %s Lng %s" % (latitude, longitude),
                date_time_process,
                date_time_created,
                '', 
                ''
                ]
        data.append(item)
    statuses = {
                "sEcho": 1,
                "iTotalRecords": vehicles.count(),
                "iTotalDisplayRecords": vehicles.count(),
                "aaData": data
                } 
    json = simplejson.dumps(statuses)
    return HttpResponse(json, mimetype='application/json')

Related: https://stackoverflow.com/a/2143599/3015186 – Niko Föhr Oct 27 '17 at 09:24 — Niko Föhr, Oct 27 '17 at 09:24

score 191 · Accepted Answer · answered Apr 29 '13 at 21:32

191

I have found the solution to this issue using ObjectDoesNotExist on this way

from django.core.exceptions import ObjectDoesNotExist
......

try:
  # try something
except ObjectDoesNotExist:
  # do something

After this, my code works as I need

Thanks any way, your post help me to solve my issue

answered Apr 29 '13 at 21:32

Carlos

4,299
5
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36

That'll work, but it's not really the best way. You should figure what class of object is represented by `vehicledevice.device.devicetrack_set`, and then catch `.DoesNotExist`. – mipadi Apr 29 '13 at 23:00
I was trying to find that, also I was trying to guess, cause I couldn't find the solution, after reading some doc I found this way Could you try to edit the code please – Carlos Apr 29 '13 at 23:11
1

Look in the class that represents `vehicledevice.device`, and find out what the related model for the `devicetrack` attribute is. – mipadi Apr 29 '13 at 23:12
(It's not possible for me to determine that without your model definitions.) – mipadi Apr 29 '13 at 23:12
It would be helpful if you actually included the exact output of the exception that is occurring – storm_m2138 Mar 13 '18 at 21:24
@mipadi would be nice to know WHY it is so important to use the `ActualClass.DoesNotExist` exception? – benzkji Jan 05 '19 at 14:26
1

I'm assuming it's important so that you're not inadvertently catching a `DoesNotExist` for something else...the whole "explicit is better than implicit" zen stuff – Will Gordon Jun 01 '19 at 01:37

score 173 · Answer 2 · answered Apr 24 '13 at 00:12

173

This line

 except Vehicle.vehicledevice.device.DoesNotExist

means look for device instance for DoesNotExist exception, but there's none, because it's on class level, you want something like

 except Device.DoesNotExist

answered Apr 24 '13 at 00:12

Dmitry Shevchenko

31,814
10
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I have tried to do that but the debug on firefox gives me: DoesNotExist at /tracking/request/statuses VehicleDevice matching query does not exist. Lookup parameters were {'is_joined__exact': True} – Carlos Apr 24 '13 at 00:29
This is expected and only means that you request an object that does not indeed exist. You should look at your data, or the logic behind it – Dmitry Shevchenko Apr 24 '13 at 00:49
1

Thanks for you help I have found my answer on a exception management using ObjectDoesNotExist Thanks a lot for your time – Carlos Apr 29 '13 at 21:33
I meant to upvote this answer, but by accident downvoted. As I discovered too late I am unable to change my vote from down to up, sorry... – LMB Sep 22 '20 at 09:49

score 26 · Answer 3 · answered Nov 15 '19 at 07:42

26

The solution that i believe is best and optimized is:

try:
   #your code
except "ModelName".DoesNotExist:
   #your code

answered Nov 15 '19 at 07:42

Syed_Shahiq

566
6
13

Hasan Khan · Answer 4 · 2021-04-22T16:33:35.003

9

First way:

try:
   # Your code goes here
except Model.DoesNotExist:
   # Handle error here

Another way to handle not found in Django. It raises Http404 instead of the model’s DoesNotExist exception.

https://docs.djangoproject.com/en/3.1/topics/http/shortcuts/#get-object-or-404

from django.shortcuts import get_object_or_404

def get_data(request):
    obj = get_object_or_404(Model, pk=1)

edited Apr 22 '21 at 16:33

answered Jan 06 '21 at 15:30

Hasan Khan

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Model.DoesNotExist doesn't works for me. Next answer is fine. – Pierre Anken Jul 09 '22 at 18:24

Django DoesNotExist

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