diff -r 8d941af65caf -r 77b6da96e6f1 web/lib/django/contrib/gis/db/models/proxy.py --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/web/lib/django/contrib/gis/db/models/proxy.py Wed Jun 02 18:57:35 2010 +0200 @@ -0,0 +1,64 @@ +""" +The GeometryProxy object, allows for lazy-geometries. The proxy uses +Python descriptors for instantiating and setting Geometry objects +corresponding to geographic model fields. + +Thanks to Robert Coup for providing this functionality (see #4322). +""" + +class GeometryProxy(object): + def __init__(self, klass, field): + """ + Proxy initializes on the given Geometry class (not an instance) and + the GeometryField. + """ + self._field = field + self._klass = klass + + def __get__(self, obj, type=None): + """ + This accessor retrieves the geometry, initializing it using the geometry + class specified during initialization and the HEXEWKB value of the field. + Currently, only GEOS or OGR geometries are supported. + """ + if obj is None: + # Accessed on a class, not an instance + return self + + # Getting the value of the field. + geom_value = obj.__dict__[self._field.attname] + + if isinstance(geom_value, self._klass): + geom = geom_value + elif (geom_value is None) or (geom_value==''): + geom = None + else: + # Otherwise, a Geometry object is built using the field's contents, + # and the model's corresponding attribute is set. + geom = self._klass(geom_value) + setattr(obj, self._field.attname, geom) + return geom + + def __set__(self, obj, value): + """ + This accessor sets the proxied geometry with the geometry class + specified during initialization. Values of None, HEXEWKB, or WKT may + be used to set the geometry as well. + """ + # 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, self._klass) 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 or isinstance(value, (basestring, buffer)): + # Set with None, WKT, HEX, or WKB + pass + else: + raise TypeError('cannot set %s GeometryProxy with value of type: %s' % (obj.__class__.__name__, type(value))) + + # Setting the objects dictionary with the value, and returning. + obj.__dict__[self._field.attname] = value + return value