gis: added get_srid() spatial backend utility that takes into account -1 SRID values; removed from_hex flag from GEOS initialization; added tests for SRID values, and changed test_gdal module docstring.

git-svn-id: http://code.djangoproject.com/svn/django/branches/gis@6596 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/gis/db/backend/oracle/field.py

@@ -4,7 +4,7 @@ from django.db import connection
 from django.db.backends.util import truncate_name
 from django.db.models.fields import Field # Django base Field class
 from django.contrib.gis.geos import GEOSGeometry
-from django.contrib.gis.db.backend.util import GeoFieldSQL
+from django.contrib.gis.db.backend.util import get_srid, GeoFieldSQL
 from django.contrib.gis.db.backend.oracle.adaptor import OracleSpatialAdaptor
 from django.contrib.gis.db.backend.oracle.query import ORACLE_SPATIAL_TERMS, TRANSFORM
 
@@ -118,8 +118,7 @@ class OracleSpatialField(Field):
 
             # Getting the SRID of the geometry, or defaulting to that of the field if
             # it is None.
-            if value.srid is None: srid = self._srid
-            else: srid = value.srid
+            srid = get_srid(self, value)
             
             # The adaptor will be used by psycopg2 for quoting the WKT.
             adapt = OracleSpatialAdaptor(value)

django/contrib/gis/db/backend/postgis/field.py

@@ -2,7 +2,7 @@ from types import StringType, UnicodeType
 from django.db import connection
 from django.db.models.fields import Field # Django base Field class
 from django.contrib.gis.geos import GEOSGeometry, GEOSException 
-from django.contrib.gis.db.backend.util import GeoFieldSQL
+from django.contrib.gis.db.backend.util import get_srid, GeoFieldSQL
 from django.contrib.gis.db.backend.postgis.adaptor import PostGISAdaptor
 from django.contrib.gis.db.backend.postgis.query import POSTGIS_TERMS, TRANSFORM
 from psycopg2 import Binary
@@ -109,8 +109,7 @@ class PostGISField(Field):
 
             # Getting the SRID of the geometry, or defaulting to that of the field if
             # it is None.
-            if value.srid is None: srid = self._srid
-            else: srid = value.srid
+            srid = get_srid(self, value)
 
             # The adaptor will be used by psycopg2 for quoting the WKB.
             adapt = PostGISAdaptor(value, srid)

django/contrib/gis/db/backend/util.py

@@ -6,3 +6,13 @@ class GeoFieldSQL(object):
     def __init__(self, where=[], params=[]):
         self.where = where
         self.params = params
+
+def get_srid(field, geom):
+    """
+    Gets the SRID depending on the value of the SRID setting of the field
+    and that of the given geometry.
+    """
+    if geom.srid is None or (geom.srid == -1 and field._srid != -1):
+        return field._srid
+    else:
+        return geom.srid

django/contrib/gis/geos/base.py

@@ -48,14 +48,12 @@ class GEOSGeometry(object):
         The `srid` keyword is used to specify the Source Reference Identifier
          (SRID) number for this Geometry.  If not set, the SRID will be None.
         """ 
-        from_hex = False
         if isinstance(geo_input, UnicodeType):
             # Encoding to ASCII, WKT or HEXEWKB doesn't need any more.
             geo_input = geo_input.encode('ascii')
         if isinstance(geo_input, StringType):
             if hex_regex.match(geo_input):
                 # If the regex matches, the geometry is in HEX form.
-                from_hex = True
                 sz = c_size_t(len(geo_input))
                 buf = create_string_buffer(geo_input)
                 g = lgeos.GEOSGeomFromHEX_buf(buf, sz)
@@ -86,10 +84,6 @@ class GEOSGeometry(object):
         # Setting the SRID, if given.
         if srid and isinstance(srid, int): self.srid = srid
 
-        # Exported HEX from other GEOS geometries will have -1 SRID -- 
-        # set here to 0, when the SRID is not explicitly given.
-        if not srid and from_hex: self.srid = 0
-
         # Setting the class type (e.g., 'Point', 'Polygon', etc.)
         self.__class__ = GEOS_CLASSES[self.geom_type]
 
@@ -422,6 +416,8 @@ class GEOSGeometry(object):
         included in this representation, because the GEOS C library uses
         -1 by default, even if the SRID is set.
         """
+        # A possible faster, all-python, implementation: 
+        #  str(self.wkb).encode('hex')
         sz = c_size_t()
         h = lgeos.GEOSGeomToHEX_buf(self._ptr(), byref(sz))
         return string_at(h, sz.value)

django/contrib/gis/tests/geoapp/tests.py

@@ -138,10 +138,12 @@ class GeoModelTest(unittest.TestCase):
         #  the pre-transformed points.  Oracle does not have the 3084 SRID.
         if not oracle:
             h = City.objects.transform('point', srid=htown.srid).get(name='Houston')
+            self.assertEqual(3084, h.point.srid)
             self.assertAlmostEqual(htown.x, h.point.x, 8)
             self.assertAlmostEqual(htown.y, h.point.y, 8)
 
         p = City.objects.transform('point', srid=ptown.srid).get(name='Pueblo')
+        self.assertEqual(2774, p.point.srid)
         self.assertAlmostEqual(ptown.x, p.point.x, 7)
         self.assertAlmostEqual(ptown.y, p.point.y, 7)
 

django/contrib/gis/tests/test_gdal.py

@@ -1,3 +1,7 @@
+"""
+Module for executing all of the GDAL tests.  None
+of these tests require the use of the database.
+"""
 from unittest import TestSuite, TextTestRunner
 
 # Importing the GDAL test modules.
@@ -20,5 +24,5 @@ def suite():
     return s
 
 def run(verbosity=1):
-    "Runs the tests that do not require geographic (GEOS, GDAL, etc.) models."
+    "Runs the GDAL tests."
     TextTestRunner(verbosity=verbosity).run(suite())

django/contrib/gis/tests/test_geos.py

@@ -607,6 +607,21 @@ class GEOSTest(unittest.TestCase):
         self.assertEqual(32021, gc.srid)
         for i in range(len(gc)): self.assertEqual(32021, gc[i].srid)
 
+        # GEOS may get the SRID from HEXEWKB
+        # 'POINT(5 23)' at SRID=4326 in hex form -- obtained from PostGIS
+        # using `SELECT GeomFromText('POINT (5 23)', 4326);`.
+        hex = '0101000020E610000000000000000014400000000000003740'
+        p1 = fromstr(hex)
+        self.assertEqual(4326, p1.srid)
+
+        # However, when HEX is exported, the SRID information is lost
+        # and set to -1.  Essentially, the 'E' of the EWKB is not
+        # encoded in HEX by the GEOS C library for some reason.
+        p2 = fromstr(p1.hex)
+        self.assertEqual(-1, p2.srid)
+        p3 = fromstr(p1.hex, srid=-1) # -1 is intended.
+        self.assertEqual(-1, p3.srid)
+
     def test16_mutable_geometries(self):
         "Testing the mutability of Polygons and Geometry Collections."
         ### Testing the mutability of Polygons ###