Context Navigation

Changes between Version 86 and Version 87 of GeoDjango

v86	v87
82	82	* '''Q:''' Per [http://groups.google.com/group/django-developers/browse_thread/thread/9f6c70864bfa7f2e/ this discussion] in {{{django-developers}}}, "I can do spatial queries if they are directly between two models with polygon fields but I can't seem to get at the spatial queries through foreign keys."
83	83	* Geographic queries require {{{GeoManager}}}, even if the model does not have a geographic field itself (in the case of a foreign key to a geo-field). The reply in the discussion gives detail into why.
	84	* '''Q:''' Why are the OGRGeometry methods {{{transform}}} and {{{transform_to}}} separate?
	85	* Because these map to the separate OGR routines [http://www.gdal.org/ogr/ogr__api_8h.html#59a5b3f954b11cfbf6e78807c28d6090 OGR_G_Transform] and [http://www.gdal.org/ogr/ogr__api_8h.html#43af4c2127cea0a5059692a62c0feb63 OGR_G_TransformTo]. Specifically, the {{{transform}}} routine takes a CoordTransform object as a parameter, whereas the {{{transform_to}}} routine takes a SpatialReference object. The {{{transform_to}}} "function requires internal creation and initialization of [a CoordTransform] object [and] it is significantly more expensive to use this function to transform many geometries than it is to create the [CoordTransform object] in advance, and call transform() with that transformation. This function exists primarily for convenience when only transforming a single geometry."
84	86
85	87	= Example =