Most of the explanations I've read for geography and geometry seem to suggest that one must only use either geometry or geography, and that the only way to use both is to cast/convert between one and the other on-the-fly. But is this actually the case?
Why not save two points?
googlemaps_placeid = models.CharField(max_length=254)
geography = models.PointField(geography=True)
geometry= models.PointField(srid=3348) #Statistics Canada Lambert projection
Most of the queries from my users will be of the type "Show me all points within roughly 20km from this point, and order them from nearest to furthest". Even though the data has points all over Canada, the user is only interested in points within a small locality with any given query, so the
geometry PointField would suffice.
If distance measurements in meters are required (as opposed to simply ordering them from nearest to furthest), then the
geography PointField will be used.
Are there any flaws with this plan? If not, what is the actual syntax for saving the two PointFields? (I've searched all over for this since GeoDjango docs are severely lacking, and all I've found is this with no accepted answer: https://stackoverflow.com/questions/24921545/how-to-assign-to-a-django-pointfield-model-attribute)