CODEWITHSUNDEEP
pythongeodjango
Prasanna vasu
Prasanna vasu

Reputation: 33

Geodjango-query with distance lookupsss

I want to sort my result based on the distance calculated in the geodjango query.
I tried with two methods but they are throwing errors.

models.py

class Partner(models.Model):
 name = models.CharField(max_length=255)
 address = models.CharField(max_length=255)
 location = models.PointField(u"longitude/latitude",geography=True, blank=True, null=True)

views.py

method 1:

testing = Partner.objects.filter(location__distance_lte=(pnt, D(km=40))).annotate(distance=Distance('location', pnt)).order_by('distance')
print(testing)

Error:

Internal Server Error: /partner/filter/
Traceback (most recent call last):
 File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/exception.py", line 41, in inner
 response = get_response(request)
 File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 187, in _get_response
 response = self.process_exception_by_middleware(e, request)
 File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 185, in _get_response
 response = wrapped_callback(request, *callback_args, **callback_kwargs)
 File "/home/prasanna/Projects/partner_server/partner/views.py", line 79, in Filter_function
 print(testing.annotate(distance=Distance('location', pnt)).order_by('distance'))
TypeError: __init__() takes from 1 to 2 positional arguments but 3 were given

method 2:

testing = Partner.objects.filter(location__distance_lte=(pnt, D(km=40))).annotate(distance=Distance('location', pnt)).order_by('distance')
print(testing)

Error:

Internal Server Error: /partner/filter/
Traceback (most recent call last):
 File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/exception.py", line 41, in inner
 response = get_response(request)
 File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 187, in _get_response
 response = self.process_exception_by_middleware(e, request)
 File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 185, in _get_response
 response = wrapped_callback(request, *callback_args, **callback_kwargs)
 File "/home/prasanna/Projects/partner_server/partner/views.py", line 79, in Filter_function
 print(testing.distance(pnt).order_by('distance'))
AttributeError: 'QuerySet' object has no attribute 'distance'

Upvotes: 1

Views: 298

Answers (1)

Muhammad Tareq
Muhammad Tareq

Reputation: 1278

Your query is correct but i think you missed something or you mixed between two types of Distance and the first one usage is different from the second one.

this one is a Measurement Object 1- from django.contrib.gis.measure import Distance

and this one is one ofGeographic Database Functions 2-from django.contrib.gis.db.models.functions import Distance

the second one will iterate over every object (row in db) in a comparison manner that the annotate function understands,however the first function is only a basic measurement function that cannot iterate or behave as comparison function

you can refer to django docs and see the difference

Measurement : https://docs.djangoproject.com/en/2.1/ref/contrib/gis/measure/

DB Function : https://docs.djangoproject.com/en/2.1/ref/contrib/gis/functions/#django.contrib.gis.db.models.functions.Distance

Upvotes: 1

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