# Copyright (c) 2011 Philip Neustrom <email@example.com>
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
from django.contrib.gis.db import models
from django.contrib.gis.geos import *
Creates a GeometryCollection pseudo-field from the provided
component fields. When accessed, the CollectionFrom field will
return a GeometryCollection from the provided component fields.
When set to a value (upon model save) the geometries contained in
the CollectionFrom field are broken out and placed into their
relevant component fields.
points = models.MultiPointField()
lines = models.MultiLineStringField()
polys = models.MultiPolygonField()
geom = CollectionFrom(points='points', lines='lines',
Then when you access the 'geom' attribute on instances of MyModel
you'll get a GeometryCollection with your points, lines and polys.
When you set the 'geom' attribute to a GeometryCollection and save
an instance of MyModel the GeometryCollection is broken into points,
lines and polygons and placed into the provided fields.
This field is useful when you want to deal with GeometryCollections
but still must maintain separate geometry fields on the model. For
instance, GeoDjango does not currently allow you to filter (with
geometry operations) based on GeometryCollections due to issues
with the underlying libraries. Someday this may be fixed. But
until then, we've got this Field.
NOTES: This field will add a column to the db, but it won't ever
store anything there except null. There's probably a way
around this. TODO.
def __init__(self, *args, **kwargs):
self.points_name = kwargs.pop('points') if 'points' in kwargs else None
self.lines_name = kwargs.pop('lines') if 'lines' in kwargs else None
self.polys_name = kwargs.pop('polys') if 'polys' in kwargs else None
super(CollectionFrom, self).__init__(*args, **kwargs)
self.null = True
def contribute_to_class(self, cls, name):
setattr(cls, name, CollectionDescriptor(self))
super(models.GeometryField, self).contribute_to_class(cls, name)
def finalize(self, sender, **kws):
self._connected_to = sender
def pre_model_save(self, instance, raw, **kws):
if not 'sender' in kws:
geom_collection = instance.__dict__.get(
'_explicit_set_%s' % self.attname, None)
if geom_collection is None:
# They didn't set an explicit GeometryCollection.
points, lines, polys = , , 
points_geom, lines_geom, polys_geom = None, None, None
for geom in geom_collection:
if type(geom) is Point:
if type(geom) is MultiPoint:
points += [g for g in geom]
if type(geom) is LineString or type(geom) is LinearRing:
if type(geom) is MultiLineString:
lines += [g for g in geom]
if type(geom) is Polygon:
if type(geom) is MultiPolygon:
polys += [g for g in geom]
points_geom = MultiPoint(points, srid=points.srid)
lines_geom = MultiLineString(lines, srid=lines.srid)
polys_geom = MultiPolygon(polys, srid=polys.srid)
setattr(instance, self.points_name, points_geom)
setattr(instance, self.lines_name, lines_geom)
setattr(instance, self.polys_name, polys_geom)
# Set ourself to None to avoid saving any data in our column.
setattr(instance, self.name, None)
instance.__dict__[self.name] = None
def __init__(self, field):
self._field = field
def __get__(self, instance=None, owner=None):
if instance is None:
"The '%s' attribute can only be accessed from %s instances."
% (self._field.name, owner.__name__))
set_field_value = instance.__dict__.get(
'_explicit_set_%s' % self._field.attname, None)
# Return the value they set for the field rather than our
# constructed GeometryCollection.
enum_points, enum_lines, enum_polys = , , 
points = getattr(instance, self._field.points_name)
enum_points = [p for p in points]
lines = getattr(instance, self._field.lines_name)
enum_lines = [l for l in lines]
polys = getattr(instance, self._field.polys_name)
enum_polys = [p for p in polys]
geoms = enum_points + enum_lines + enum_polys
return GeometryCollection(geoms, srid=self._field.srid)
def __set__(self, obj, value):
# The OGC Geometry type of the field.
gtype = self._field.geom_type
# The geometry type must match that of the field -- unless the
# general GeometryField is used.
if (isinstance(value, GeometryCollection) and
(str(value.geom_type).upper() == gtype or gtype == 'GEOMETRY')):
# Assigning the SRID to the geometry.
if value.srid is None:
value.srid = self._field.srid
elif value is None:
elif isinstance(value, (basestring, buffer)):
# Set with WKT, HEX, or WKB
value = GEOSGeometry(value, srid=self._field.srid)
'cannot set %s CollectionFrom with value of type: %s' %
obj.__dict__['_explicit_set_%s' % self._field.attname] = value