Question

I am trying to do a proximity_fetch with the GeoModel class for Google App Engine. The entity I want to use it for is ndb and I am not sure what I need to download and import and what I can just import from google in my python code. The websites seem to be a little outdated and I was wondering if anyone had more pertinant information. This is what I have so far and it is telling me that Location has no attribute proximity_fetch, which I know but I am not sure how I should define it in the Location(ndb.Model) class.

        g = geocoders.Google()

        place, (lat, lng) = g.geocode(inputlocation, exactly_one=False)


        bound = 20
        upper = lat + bound
        lower = lat - bound
        left = lng + bound
        right = lng - bound

        locations = []

        if lat and lng:
            locations = Location.proximity_fetch(
                                                 Location.query(),
                                                 geotypes.Point(lat, lng),
                                                 max_results=50,
                                                 max_distance=500000) 

Also when I try to import geomodel and geotype which seem pretty vital for this it gives me an import error and I am not sure where to get them from.

Any help or examples would be greatly appreciated!

Answer 1

You should first checkout the latest code from the SVN repository. You can find the information about this at http://code.google.com/p/geomodel/source/checkout

After you have the code locally on your machine, inside the main directory there is a directory called geo. You should copy this directory into your GAE project. Then in your code, you import what you need from this package. For example:

from geo import geomodel

Now, regarding your Location model, in order to be able to execute a proximity_fetch Query, your model should extend the provided model in geomodel called GeoModel. Thus, you should have something like this:

class Location(ndb.Model, GeoModel):
....

Notice that GeoModel currently uses the “old” GAE datastore layer db and not ndb that you are using in your code. However, it shouldn’t cause any trouble.

For more information on how to use geomodel, you should also take a look at the demos that also exist in the code you got from SVN. You can find them in the demos directory.

Hope this helps!