Adds to Melange a tags framework based on taggable-mixin.
The taggable-mixin allowed only tag per Datastore model. This is extended
framework allows any arbitrary number of tags per Datastore model. Also,
now one can define different models for different Tag types which are all
inherited from the base Tag model provided by taggable-mixin.
The GHOPTask model makes use of 2 tags per model, one for difficulty and the
other for task_type, both using the tags framework.
Reviewed by: Paweł Sołyga
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)