Django-GeoField

A lightweight Django Geo Field to save and handle Geo Points. It supports to search the nearby points by their geohash.

Quick start

Install django-geofield
```
 pip install django-geofield
```

Define GeoPositionField in your Model like this::

 class Point(models.Model):
     ...
     position = GeoPositionField(db_index=True)

Run python manage.py makemigrations and python manage.py migrate to make it effect

The field will save a geo point with a string into database like this :

 Point.objects.create(
                 position=GeoPosition(lat, lon, precision=6))

 'wtmm7w,30.49145747305400533377905958332121372222900390625,120.042387425481223317547119222581386566162109375'

If you want to query the points whose geohash is matched exactly with the given point , you can :
```
 pos = Point.objects.get(id=1)

 points_matched = Point.objects.filter(position__geoprecise=pos.position.geohash)
```
The '__geoprecise' lookup will find all points have the same geohash.
If you want to query the points in expand area to eliminate the geohash's marginal error, you can :
```
 pos = Point.objects.get(id=1)

 points_matched = Point.objects.filter(position__geosearch=pos.position.geohash)
```
The '__geosearch' lookup will find all points have one of 9 ( 1 center point and 8 expand point) geohash .
If you want to query the points within a specific range , you should lookup the geohash table to get the geohash length you want, then just search the cropped length.
```
 pos = Point.objects.get(id=1)

 points_matched = Point.objects.filter(position__geosearch=pos.position.geohash[0:4])
```