Bump. It surprises me that no-one has any comments on this, based on
the number of other threads discussing geohashes.
In summary there are two issues here. 1. SDK and GAE do different
things; any comments? 2. Does anyone have a robust method for finding
bounding boxes containing a point?
Thanks, and apologies for the bump but this has me stumped.
David
On Apr 12, 6:21 pm, JDT <john.david....@googlemail.com> wrote:
> Hello,
>
> I am trying to use the Date Range Recipe [1] in the App Engine
> Cookbook, to find bounding boxes containing a particular point.
>
> The method used in the recipe allows searching for events occurring on
> particular days by storing the event start and end dates in a list
> (date_range).
>
> This allows the query:
> ... WHERE date_range >= :1 AND date_range <= :1, date_in_question)
> to work because [2] "In a query, comparing a list property to a value
> performs the test against the list members: ... list_property < value
> tests if any of the members of the list are less than the given value,
> and so forth."
>
> I have taken the same method and used it for geohashes. In my case I
> have many suppliers who deliver to geographical areas. These areas
> overlap and are not exclusive.
> I have stored the delivery areas using a bounding box defined by two
> geohases, one for the NE point and one for the SW point:
>
> delivery_area = [NEhash, SWhash]
>
> When searching, I geohash the search position, then search in the
> list, as in the recipe:
>
> searchpositionhash = geohash.encode
> (searchpositionlat,searchpositionlon)
> sellers_who_deliver = db.GqlQuery("SELECT * FROM Sellers WHERE
> delivery_area <= :1 AND delivery_area >= :1, searchpositionhash )
>
> This works without any problems in the SDK, but no responses are
> returned in the production environment. Understandably it is
> frustrating when the SDK works differently from the production server,
> but my frustration is compounded by my inability to find any posts
> showing similar problems.
>
> Has anyone used lists of geohashes to define bounding boxes, if so
> what was your experience of searching?
> Can anyone see anything wrong with the method I am using?
> Finally, if there is a simpler method of finding bounding boxes,
> matching a point please, please, please, kick me in the right
> direction!
>
> Thanks,
>
> David
>
> [1]http://appengine-cookbook.appspot.com/recipe/how-to-query-by-date-range/
> [2]http://code.google.com/appengine/docs/python/datastore/typesandproper...
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