Add support of PostGIS's SnapToGrid function

[norn]

I'd like to have support of SnapToGrid function from PostGIS. I made patch and it works for me. I believe it is simple enough to be implemented in trunk.

[norn]

SnapToGrid support patch against django-1.0.2-final

[jbronn]

SVN diff of user-provided patch

[jbronn]

I'm +1 on having this feature in GeoDjango. However, we'll have to talk about implementation details -- I see you have this done on the geometry in-place rather than attaching a new geometry on the GeoQuerySet (otherwise you could've just used the _geom_attribute method to simplify the implementation). I wonder if this option should be an option for all methods, e.g., GeoModel.objects.intersection(other, in_place=True).

Also, I'll need tests before including it trunk, but otherwise it's a very good start. Thanks for contributing.

[norn]

'In place' method was chosen because I have a need of chaining snaptogrid after transform().
Also I am interested in filtering out records with empty geometry field after snapping, but I have no idea how to implement it in effective way (avoiding double calculation in SQL).
I think your decision about in_place is quite useful and will allow building longer chains.

[(none)]

Milestone post-1.0 deleted

[jbronn]

Now that values() and defer() work, there's really no need to do the in_place option anymore.

[jbronn]

(In [10369]) Fixed #9745 -- Added the GeoQuerySet methods snap_to_grid and geojson.

[Jacob]

Milestone 1.1 deleted