from django.contrib.gis.geos import Point
from django.utils import simplejson
from django.core.serializers import json 

def get_pt_or_bbox(rg):
  
    lat = rg.get('lat','')
    lon = rg.get('lon','')
    if lat and lon: 
        return Point(float(lon), float(lat), srid=4326)
    bbox = rg.get('bbox','')
    if bbox:
        b = eval(bbox)
        p1 = Point((b[0][1],b[0][0]))
        p2 = Point((b[1][1],b[1][0]))
        return p1.union(p2).envelope
    return None