gis: lazy-geometry support has landed -- thanks Robert Coup!

git-svn-id: http://code.djangoproject.com/svn/django/branches/gis@5657 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/gis/db/models/__init__.py

@@ -14,4 +14,4 @@ from django.contrib.gis.db.models.fields import \
      GeometryCollectionField
 
 # The geographic mixin class.
-from GeoMixin import GeoMixin
+from mixin import GeoMixin

django/contrib/gis/db/models/fields/__init__.py

@@ -1,5 +1,6 @@
 # The Django base Field class.
 from django.db.models.fields import Field
+from django.contrib.gis.db.models.proxy import GeometryProxy
 from django.contrib.gis.db.models.postgis import POSTGIS_TERMS, quotename
 from django.contrib.gis.oldforms import WKTField
 from django.utils.functional import curry
@@ -86,9 +87,20 @@ class GeometryField(Field):
         else:
             return post_sql
 
+    def _post_delete_sql(self, style, db_table):
+        "Drops the geometry column."
+        sql = style.SQL_KEYWORD('SELECT ') + \
+            style.SQL_KEYWORD('DropGeometryColumn') + '(' + \
+            style.SQL_TABLE(quotename(db_table)) + ', ' + \
+            style.SQL_FIELD(quotename(self.column)) +  ');'
+        return sql
+
     def contribute_to_class(self, cls, name):
         super(GeometryField, self).contribute_to_class(cls, name)
 
+        # setup for lazy-instantiated GEOSGeometry objects
+        setattr(cls, self.attname, GeometryProxy(self))
+
         # Adding needed accessor functions
         setattr(cls, 'get_%s_geos' % self.name, curry(cls._get_GEOM_geos, field=self))
         setattr(cls, 'get_%s_ogr' % self.name, curry(cls._get_GEOM_ogr, field=self, srid=self._srid))

django/contrib/gis/db/models/mixin.py

@@ -1,4 +1,5 @@
 # GEOS Routines
+from warnings import warn
 from django.contrib.gis.geos import GEOSGeometry, hex_to_wkt, centroid, area
 from django.contrib.gis.gdal import OGRGeometry, SpatialReference
 
@@ -11,7 +12,8 @@ class GeoMixin:
     # routines are present for instantiations of the models.
     def _get_GEOM_geos(self, field):
         "Returns a GEOS Python object for the geometry."
-        return GEOSGeometry(getattr(self, field.attname), 'hex')
+        warn("use model.%s" % field.attname, DeprecationWarning) 
+        return getattr(self, field.attname)
 
     def _get_GEOM_ogr(self, field, srid):
         "Returns an OGR Python object for the geometry."
@@ -20,6 +22,7 @@ class GeoMixin:
 
     def _get_GEOM_srid(self, srid):
         "Returns the spatial reference identifier (SRID) of the geometry."
+        warn("use model.geometry_field.srid", DeprecationWarning)
         return srid
 
     def _get_GEOM_srs(self, srid):
@@ -28,17 +31,17 @@ class GeoMixin:
 
     def _get_GEOM_wkt(self, field):
         "Returns the WKT of the geometry."
-        hex = getattr(self, field.attname)
-        return hex_to_wkt(hex)
+        warn("use model.%s.centroid.wkt" % field.attname, DeprecationWarning) 
+        return getattr(self, field.attname).wkt
 
     def _get_GEOM_centroid(self, field):
         "Returns the centroid of the geometry, in WKT."
-        hex = getattr(self, field.attname)
-        return centroid(hex)
+        warn("use model.%s.centroid.wkt" % field.attname, DeprecationWarning) 
+        return getattr(self, field.attname).centroid.wkt
     
     def _get_GEOM_area(self, field):
         "Returns the area of the geometry, in projected units."
-        hex = getattr(self, field.attname)
-        return area(hex)
+        warn("use model.%s.area" % field.attname, DeprecationWarning)
+        return getattr(self, field.attname).area
 
 

django/contrib/gis/db/models/postgis.py

@@ -38,7 +38,7 @@ POSTGIS_OPERATORS = {
 
 # PostGIS Geometry Functions -- most of these use GEOS.
 POSTGIS_GEOMETRY_FUNCTIONS = {
-    'distance' : 'Distance',
+    #'distance' : 'Distance', -- doesn't work right now.
     'equals' : 'Equals',
     'disjoint' : 'Disjoint',
     'touches' : 'Touches',

django/contrib/gis/db/models/proxy.py

@@ -0,0 +1,30 @@
+"""
+  The GeometryProxy object, allows for lazy-geometries.
+
+  Thanks to Robert Coup for providing this functionality (see #4322).
+"""
+
+# GEOS Routines 
+from django.contrib.gis.geos import GEOSGeometry, GEOSException 
+
+# TODO: docstrings & comments
+class GeometryProxy(object): 
+    def __init__(self, field): 
+        self._field = field 
+     
+    def __get__(self, obj, type=None): 
+        geom_value = obj.__dict__[self._field.attname] 
+        if (geom_value is None) or (isinstance(geom_value, GEOSGeometry)): 
+            geom = geom_value 
+        else: 
+            geom = GEOSGeometry(geom_value) 
+            setattr(obj, self._field.attname, geom) 
+        return geom 
+     
+    def __set__(self, obj, value): 
+        if isinstance(value, GEOSGeometry): 
+            if value and ((value.srid is None) and (self._field._srid is not None)): 
+                value.set_srid(self._field._srid) 
+     
+        obj.__dict__[self._field.attname] = value 
+        return value