Creating and saving GeoModel-derived entitiesTo use the GeoModel class, simply declare a new model class inheriting from the geo.GeoModel class like so: from geo.geomodel import GeoModel
class MyEntity(GeoModel):
foo = db.StringProperty()
bar = db.IntegerProperty() Currently, only single-point entities are supported. Entities of the new MyEntity kind will have a location property of type db.GeoPt, which can be set as needed. Before put()'ing entities to the datastore, make sure to call update_location to synchronize the entity's underlying geocell indexing properties: some_entity = MyEntity(location=db.GeoPt(37, -122),
foo='Hello',
bar=5)
...
some_entity.location = db.GeoPt(38, -122)
some_entity.update_location()
some_entity.put()Querying your entitiesThere are currently two types of basic geospatial queries supported by the GeoModel library: - bounding box queries
- proximity (nearest-n) queries
To perform a bounding box query, use the bounding_box_fetch class method like so: results = MyEntity.bounding_box_fetch(
MyEntity.all().filter('bar >', 5), # Rich query!
geotypes.Box(39, -121, 37, -123),
max_results=10)Be careful not to request too many results or else you'll get a datastore or request timeout! To perform a proximity query, use the proximity_fetch class method like so: resuts = MyEntity.proximity_fetch(
MyEntity.all().filter('bar <', 10), # Rich query!
geotypes.Point(39, -121), # Or db.GeoPt
max_results=10,
max_distance=80467) # Within 50 miles.Note that for rich queries on multiple properties you'll need to set up the proper indexes in your index.yaml file. Testing your app on the development server should populate that file with the required indexes. Also, GeoModel currently requires many internal properties on each entity (one for each geocell resolution), which can lead to messy looking index.yaml files. That's something that will hopefully change in future versions.
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Looks fantastic
I'll be giving this a go very soon.