Query REST API latitude and longitude - django-rest-framework

Question

I want my users to query two slugs fields (latitude, longitude) and then the 2 slug fields get compared to find nearest distance within 1.5km radius and display the api according to the nearest safehouses.
For example: when the users add latitude, longitude in their query,
www.example.com/safeplace/?find=-37.8770,145.0442
This will show the nearest safeplaces within 1.5km
Here is my function
def distance(lat1, long1, lat2, long2):
R = 6371 # Earth Radius in Km
dLat = math.radians(lat2 - lat1) # Convert Degrees 2 Radians
dLong = math.radians(long2 - long1)
lat1 = math.radians(lat1)
lat2 = math.radians(lat2)
a = math.sin(dLat/2) * math.sin(dLat/2) + math.sin(dLong/2) *
math.sin(dLong/2) * math.cos(lat1) * math.cos(lat2)
c = 2 * math.atan2(math.sqrt(a), math.sqrt(1-a))
d = R * c
return d
Here is my model
class Safeplace(models.Model):
establishment = models.CharField(max_length=250)
address = models.CharField(max_length=250)
suburb = models.CharField(max_length=250)
postcode = models.IntegerField()
state = models.CharField(max_length=250)
type = models.CharField(max_length=250)
latitude = models.DecimalField(decimal_places=6,max_digits=10)
longtitude = models.DecimalField(decimal_places=6,max_digits=10)
Is there a way to run a for loop in my database? I am currently working on Django SQLite. On Views.py, how can i implement the distance function with the user input in my rest api url to find the nearest safeplace and display as REST Api?

Answer 1

What you need is to run a comparison for loop in your views.py. It is pretty difficult to execute but I will try to explain step by step.
assuming you are using that distance(lat, lng, lat2, lng2) function and trying to find the distance within 2km for example.
In views.py
import pandas as pd
class someapiview(ListAPIView):
serializer_class = SafeplaceSerializer
### Now we are creating definition which sorts parameters lng and lat ###
def get_queryset(self):
queryset = Safeplace.Objects.all()
lat = float(self.query_params.get('lag', None)
lng = float(self.query_params.get('lng', None)
### Now, we are reading your api using pandas ###
df = pd.read_json('yourapi') ## yourapi is a url to ur api
obj = []
for x in range(0, len(df)):
latx = float(df['latitude'][x])
lngx = float(df['longitude'][x])
### Calculating distance ###
km = distance(lat, lng, latx, lngx)
if km <= 2:
obj.append(df['id'][x])
### Django auto generate primary key which usually calls id ###
### Now we are going to call those pk as a queryset ###
return Safeplace.objects.filter(pk__in=obj)
I used pandas to work around, the load time might be slow if you have lots of data. However, I think this does the job. Usually Geo Django provides an efficient system to deal with long and lat, however I am not very competent in Geo Django so I cannot really tell. But I Believe this is a good work around.
UPDATE :
you can query with "www.yourapi.com/safeplace?lat=x&lng=y"
I believe you know how to set urls