How to return a record with the lowest distance from a point using geodjango?
django, geodjango
Solution
Finally a solution gathered from clues from GeoDjango distance filter with distance value stored within model - query which lead me to this post. From this information I was able to gather that you MUST SPECIFY the measure parameter in your distance query. You will see in the below snippet, I import measure as D. Then use it in the query. If you don't specify it you will get this error:
ValueError: Tuple required for `distance_lte` lookup type.
To take just the point with the lowest distance I used `order_by('distance')[:1][0]`
from spots.models import *
from django.contrib.gis.geos import *
from django.contrib.gis.measure import D
distance_m = 20000
origin = Point(28.011030, -26.029430)
closest_spot = Spot.objects.filter(point__distance_lte=(origin, D(m=distance_m))).distance(origin).order_by('distance')[:1][0]
Problem
I am using geodjango and have a collection of points in my database. To get a queryset of points within a certain area I use this: ``` queryset = Spot.objects.filter(point__distance_lte=(origin, distance_m)) ``` My question is how can I return only one point(the point with the lowest distance)from the point I have passed it? EDIT I should mention that I am passing in coordinates and wanting to create a `Point` object with them. Then pass that point in as the origin and filter against that. For example I have tried: ``` from spots.models import * from django.contrib.gis.geos import * origin = Point(28.011030, -26.029430) distance_m = 1000 queryset = Spot.objects.filter(point__distance_lte=(origin, distance_m)) for q in queryset: print q.distance ``` This snippet of code gives me this error: ``` Traceback (most recent call last): File "<console>", line 2, in <module> AttributeError: 'Spot' object has no attribute 'distance' ``` Interestingly enough if I do the following: ``` origin = Spot.objects.get(name='Montecasino').point distance_m = 1000 for city in Spot.objects.distance(origin): print(city.name, city.distance) (u'Design Quarter Parking', Distance(m=677.347841801)) (u'Montecasino', Distance(m=0.0)) (u'Fourways', Distance(m=1080.67723755)) ```