Extend taggable-mixin to support different Tag models.
Usage is pretty simple. Tag model is default in Taggable constructor but you
can call it with different model like GHOPTaskType that inherits from Tag model.
Both Taggable and Tag models have been updated and they don't use hardcoded Tag
model anymore and instead use cls of class methods or self.__class__. In case
of Taggable it's self.__tag_model.
def add_postgis_srs(srs):
"""
This function takes a GDAL SpatialReference system and adds its
information to the PostGIS `spatial_ref_sys` table -- enabling
spatial transformations with PostGIS. This is handy for adding
spatial reference systems not included by default with PostGIS.
For example, the following adds the so-called "Google Maps Mercator
Projection" (available in GDAL 1.5):
>>> add_postgis_srs(SpatialReference(900913))
Note: By default, the `auth_name` is set to 'EPSG' -- this should
probably be changed.
"""
from django.contrib.gis.models import SpatialRefSys
from django.contrib.gis.gdal import SpatialReference
if not isinstance(srs, SpatialReference):
srs = SpatialReference(srs)
if srs.srid is None:
raise Exception('Spatial reference requires an SRID to be compatible with PostGIS.')
# Creating the spatial_ref_sys model.
sr, created = SpatialRefSys.objects.get_or_create(
srid=srs.srid, auth_name='EPSG', auth_srid=srs.srid,
srtext=srs.wkt, proj4text=srs.proj4)