How To Find Nearest Point From User Location using geodjango?

Question

I am trying to find the nearest point to a location using geodjango.

I tried using the following code:

LocationInfo.objects.filter(coordinates__distance_lte=(user_location, D(km=2)))

But It only works if the location is within the specified distance (D(km=2) in this case).

I need to find the point nearest to the user without using any limit during query.

John Moutafis · Accepted Answer · 2017-09-26T14:15:06.137

21

Let's assume that your LocationInfo has it's geometry field named position:

For Django version >= 1.9:

You can use the Distance() function:

from django.contrib.gis.db.models.functions import Distance

LocationInfo.objects.annotate(
    distance=Distance('position', user_location)
).order_by('distance').first()

Which will return the nearest object to the user_location

For Django 1.6 <= version < 1.9:

You can use the .distance() method:

LocationInfo.objects.distance(user_location).order_by('distance').first()

For Django version < 1.6:

The .first() method does not exist so you have to get the first of the ordered queryset as follows:

 LocationInfo.objects.distance(user_location).order_by('distance')[:1].get()

edited Sep 26 '17 at 14:15

answered Jun 19 '17 at 07:50

John Moutafis

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I am facing the following error: TypeError: __init__() takes at most 2 arguments (3 given) on trying out the above code – sam23 Jun 19 '17 at 10:22
I am using django 1.11 in the project. – sam23 Jun 19 '17 at 10:25
Did you imported `Distance` like so: `from django.contrib.gis.db.models.functions import Distance`? – John Moutafis Jun 19 '17 at 10:28
No. I was using the one from from django.contrib.gis.measure import Distance. It works after importing from the db source. Thanks. – sam23 Jun 19 '17 at 10:30
Good to know mate, I will edit my answer to include this :) – John Moutafis Jun 19 '17 at 10:31

score 0 · Answer 2 · answered Jul 18 '17 at 06:34

This will give you the nearest location info:

LocationInfo.geo_objects.distance(user_location).order_by('distance')[0]

where geo_objects is Model manager for LocationInfo

from django.contrib.gis.db import models as gis_models

class LocationInfo(models.Model):

    geo_objects = gis_models.GeoManager()

How To Find Nearest Point From User Location using geodjango?

2 Answers2