Fixed #9745 -- Added the `GeoQuerySet` methods `snap_to_grid` and `geojson`.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10369 bcc190cf-cafb-0310-a4f2-bffc1f526a37

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

@@ -19,6 +19,7 @@ SpatialBackend = BaseSpatialBackend(name='postgis', postgis=True,
                                     envelope=ENVELOPE,
                                     extent=EXTENT,
                                     gis_terms=POSTGIS_TERMS,
+                                    geojson=ASGEOJSON,
                                     gml=ASGML,
                                     intersection=INTERSECTION,
                                     kml=ASKML,
@@ -32,6 +33,7 @@ SpatialBackend = BaseSpatialBackend(name='postgis', postgis=True,
                                     point_on_surface=POINT_ON_SURFACE,
                                     scale=SCALE,
                                     select=GEOM_SELECT,
+                                    snap_to_grid=SNAP_TO_GRID,
                                     svg=ASSVG,
                                     sym_difference=SYM_DIFFERENCE,
                                     transform=TRANSFORM,

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

@@ -38,6 +38,7 @@ if MAJOR_VERSION >= 1:
 
     # Functions used by the GeoManager & GeoQuerySet
     AREA = get_func('Area')
+    ASGEOJSON = get_func('AsGeoJson')
     ASKML = get_func('AsKML')
     ASGML = get_func('AsGML')
     ASSVG = get_func('AsSVG')
@@ -61,11 +62,12 @@ if MAJOR_VERSION >= 1:
     PERIMETER = get_func('Perimeter')
     POINT_ON_SURFACE = get_func('PointOnSurface')
     SCALE = get_func('Scale')
+    SNAP_TO_GRID = get_func('SnapToGrid')
     SYM_DIFFERENCE = get_func('SymDifference')
     TRANSFORM = get_func('Transform')
     TRANSLATE = get_func('Translate')
 
-    # Special cases for union and KML methods.
+    # Special cases for union, KML, and GeoJSON methods.
     if MINOR_VERSION1 < 3:
         UNIONAGG = 'GeomUnion'
         UNION = 'Union'
@@ -75,6 +77,11 @@ if MAJOR_VERSION >= 1:
 
     if MINOR_VERSION1 == 1:
         ASKML = False
+
+    # Only 1.3.4+ have AsGeoJson.
+    if (MINOR_VERSION1 < 3 or 
+        (MINOR_VERSION1 == 3 and MINOR_VERSION2 < 4)):
+        ASGEOJSON = False
 else:
     raise NotImplementedError('PostGIS versions < 1.0 are not supported.')
 

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

@@ -30,6 +30,9 @@ class GeoManager(Manager):
     def extent(self, *args, **kwargs):
         return self.get_query_set().extent(*args, **kwargs)
 
+    def geojson(self, *args, **kwargs):
+        return self.get_query_set().geojson(*args, **kwargs)
+
     def gml(self, *args, **kwargs):
         return self.get_query_set().gml(*args, **kwargs)
 
@@ -63,6 +66,9 @@ class GeoManager(Manager):
     def scale(self, *args, **kwargs):
         return self.get_query_set().scale(*args, **kwargs)
 
+    def snap_to_grid(self, *args, **kwargs):
+        return self.get_query_set().snap_to_grid(*args, **kwargs)
+
     def svg(self, *args, **kwargs):
         return self.get_query_set().svg(*args, **kwargs)
 

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

@@ -103,6 +103,32 @@ class GeoQuerySet(QuerySet):
         """
         return self._spatial_aggregate(aggregates.Extent, **kwargs)
 
+    def geojson(self, precision=8, crs=False, bbox=False, **kwargs):
+        """
+        Returns a GeoJSON representation of the geomtry field in a `geojson`
+        attribute on each element of the GeoQuerySet.
+
+        The `crs` and `bbox` keywords may be set to True if the users wants
+        the coordinate reference system and the bounding box to be included
+        in the GeoJSON representation of the geometry.
+        """
+        if not SpatialBackend.postgis or not SpatialBackend.geojson:
+            raise NotImplementedError('Only PostGIS 1.3.4+ supports GeoJSON serialization.')
+        
+        if not isinstance(precision, (int, long)):
+            raise TypeError('Precision keyword must be set with an integer.')
+        
+        # Setting the options flag 
+        options = 0
+        if crs and bbox: options = 3
+        elif crs: options = 1
+        elif bbox: options = 2
+        s = {'desc' : 'GeoJSON', 
+             'procedure_args' : {'precision' : precision, 'options' : options},
+             'procedure_fmt' : '%(geo_col)s,%(precision)s,%(options)s',
+             }
+        return self._spatial_attribute('geojson', s, **kwargs)
+
     def gml(self, precision=8, version=2, **kwargs):
         """
         Returns GML representation of the given field in a `gml` attribute
@@ -213,6 +239,42 @@ class GeoQuerySet(QuerySet):
                  }
         return self._spatial_attribute('scale', s, **kwargs)
 
+    def snap_to_grid(self, *args, **kwargs):
+        """
+        Snap all points of the input geometry to the grid.  How the
+        geometry is snapped to the grid depends on how many arguments
+        were given:
+          - 1 argument : A single size to snap both the X and Y grids to.
+          - 2 arguments: X and Y sizes to snap the grid to.
+          - 4 arguments: X, Y sizes and the X, Y origins.
+        """
+        if False in [isinstance(arg, (float, int, long)) for arg in args]:
+            raise TypeError('Size argument(s) for the grid must be a float or integer values.')
+
+        nargs = len(args)
+        if nargs == 1:
+            size = args[0]
+            procedure_fmt = '%(geo_col)s,%(size)s'
+            procedure_args = {'size' : size}
+        elif nargs == 2:
+            xsize, ysize = args
+            procedure_fmt = '%(geo_col)s,%(xsize)s,%(ysize)s'
+            procedure_args = {'xsize' : xsize, 'ysize' : ysize}
+        elif nargs == 4:
+            xsize, ysize, xorigin, yorigin = args
+            procedure_fmt = '%(geo_col)s,%(xorigin)s,%(yorigin)s,%(xsize)s,%(ysize)s'
+            procedure_args = {'xsize' : xsize, 'ysize' : ysize,
+                              'xorigin' : xorigin, 'yorigin' : yorigin}
+        else:
+            raise ValueError('Must provide 1, 2, or 4 arguments to `snap_to_grid`.')
+
+        s = {'procedure_fmt' : procedure_fmt,
+             'procedure_args' : procedure_args,
+             'select_field' : GeomField(),
+             }
+
+        return self._spatial_attribute('snap_to_grid', s, **kwargs)
+
     def svg(self, **kwargs):
         """
         Returns SVG representation of the geographic field in a `svg`

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

@@ -119,7 +119,7 @@ class GeoModelTest(unittest.TestCase):
     @no_oracle # Oracle does not support KML.
     @no_spatialite # SpatiaLite does not support KML.
     def test03a_kml(self):
-        "Testing KML output from the database using GeoManager.kml()."
+        "Testing KML output from the database using GeoQuerySet.kml()."
         if DISABLE: return
         # Should throw a TypeError when trying to obtain KML from a
         #  non-geometry field.
@@ -145,7 +145,7 @@ class GeoModelTest(unittest.TestCase):
 
     @no_spatialite # SpatiaLite does not support GML.
     def test03b_gml(self):
-        "Testing GML output from the database using GeoManager.gml()."
+        "Testing GML output from the database using GeoQuerySet.gml()."
         if DISABLE: return
         # Should throw a TypeError when tyring to obtain GML from a
         #  non-geometry field.
@@ -164,6 +164,38 @@ class GeoModelTest(unittest.TestCase):
             for ptown in [ptown1, ptown2]:
                 self.assertEqual('<gml:Point srsName="EPSG:4326"><gml:coordinates>-104.609252,38.255001</gml:coordinates></gml:Point>', ptown.gml)
 
+    @no_spatialite
+    @no_oracle
+    def test03c_geojson(self):
+        "Testing GeoJSON output from the database using GeoQuerySet.geojson()."
+        if DISABLE: return
+        # PostGIS only supports GeoJSON on 1.3.4+
+        if not SpatialBackend.geojson:
+            return
+
+        # Precision argument should only be an integer
+        self.assertRaises(TypeError, City.objects.geojson, precision='foo')
+        
+        # Reference queries and values.
+        # SELECT ST_AsGeoJson("geoapp_city"."point", 8, 0) FROM "geoapp_city" WHERE "geoapp_city"."name" = 'Pueblo';
+        json = '{"type":"Point","coordinates":[-104.60925200,38.25500100]}'
+        self.assertEqual(City.objects.geojson().get(name='Pueblo').geojson, json)
+
+        # SELECT ST_AsGeoJson("geoapp_city"."point", 8, 1) FROM "geoapp_city" WHERE "geoapp_city"."name" = 'Houston';
+        json = '{"type":"Point","crs":{"type":"EPSG","properties":{"EPSG":4326}},"coordinates":[-95.36315100,29.76337400]}'
+        # This time we want to include the CRS by using the `crs` keyword.
+        self.assertEqual(City.objects.geojson(crs=True, model_att='json').get(name='Houston').json, json)
+
+        # SELECT ST_AsGeoJson("geoapp_city"."point", 8, 2) FROM "geoapp_city" WHERE "geoapp_city"."name" = 'Victoria';
+        json = '{"type":"Point","bbox":[-123.30519600,48.46261100,-123.30519600,48.46261100],"coordinates":[-123.30519600,48.46261100]}'
+        # This time we include the bounding box by using the `bbox` keyword.
+        self.assertEqual(City.objects.geojson(bbox=True).get(name='Victoria').geojson, json)
+
+        # SELECT ST_AsGeoJson("geoapp_city"."point", 5, 3) FROM "geoapp_city" WHERE "geoapp_city"."name" = 'Chicago';
+        json = '{"type":"Point","crs":{"type":"EPSG","properties":{"EPSG":4326}},"bbox":[-87.65018,41.85039,-87.65018,41.85039],"coordinates":[-87.65018,41.85039]}'
+        # Finally, we set every available keyword.
+        self.assertEqual(City.objects.geojson(bbox=True, crs=True, precision=5).get(name='Chicago').geojson, json)
+        
     def test04_transform(self):
         "Testing the transform() GeoManager method."
         if DISABLE: return
@@ -620,6 +652,46 @@ class GeoModelTest(unittest.TestCase):
 
         self.assertEqual(1, qs.count())
         for pc in qs: self.assertEqual(32128, pc.point.srid)
+        
+    @no_spatialite
+    @no_oracle
+    def test27_snap_to_grid(self):
+        "Testing GeoQuerySet.snap_to_grid()."
+        if DISABLE: return
+
+        # Let's try and break snap_to_grid() with bad combinations of arguments.
+        for bad_args in ((), range(3), range(5)):
+            self.assertRaises(ValueError, Country.objects.snap_to_grid, *bad_args)
+        for bad_args in (('1.0',), (1.0, None), tuple(map(unicode, range(4)))):
+            self.assertRaises(TypeError, Country.objects.snap_to_grid, *bad_args)
+
+        # Boundary for San Marino, courtesy of Bjorn Sandvik of thematicmapping.org
+        # from the world borders dataset he provides.
+        wkt = ('MULTIPOLYGON(((12.41580 43.95795,12.45055 43.97972,12.45389 43.98167,'
+               '12.46250 43.98472,12.47167 43.98694,12.49278 43.98917,'
+               '12.50555 43.98861,12.51000 43.98694,12.51028 43.98277,'
+               '12.51167 43.94333,12.51056 43.93916,12.49639 43.92333,'
+               '12.49500 43.91472,12.48778 43.90583,12.47444 43.89722,'
+               '12.46472 43.89555,12.45917 43.89611,12.41639 43.90472,'
+               '12.41222 43.90610,12.40782 43.91366,12.40389 43.92667,'
+               '12.40500 43.94833,12.40889 43.95499,12.41580 43.95795)))')
+        sm = Country.objects.create(name='San Marino', mpoly=fromstr(wkt))
+
+        # Because floating-point arithmitic isn't exact, we set a tolerance
+        # to pass into GEOS `equals_exact`.
+        tol = 0.000000001
+
+        # SELECT AsText(ST_SnapToGrid("geoapp_country"."mpoly", 0.1)) FROM "geoapp_country" WHERE "geoapp_country"."name" = 'San Marino';
+        ref = fromstr('MULTIPOLYGON(((12.4 44,12.5 44,12.5 43.9,12.4 43.9,12.4 44)))')
+        self.failUnless(ref.equals_exact(Country.objects.snap_to_grid(0.1).get(name='San Marino').snap_to_grid, tol))
+
+        # SELECT AsText(ST_SnapToGrid("geoapp_country"."mpoly", 0.05, 0.23)) FROM "geoapp_country" WHERE "geoapp_country"."name" = 'San Marino';
+        ref = fromstr('MULTIPOLYGON(((12.4 43.93,12.45 43.93,12.5 43.93,12.45 43.93,12.4 43.93)))')
+        self.failUnless(ref.equals_exact(Country.objects.snap_to_grid(0.05, 0.23).get(name='San Marino').snap_to_grid, tol))
+
+        # SELECT AsText(ST_SnapToGrid("geoapp_country"."mpoly", 0.5, 0.17, 0.05, 0.23)) FROM "geoapp_country" WHERE "geoapp_country"."name" = 'San Marino';
+        ref = fromstr('MULTIPOLYGON(((12.4 43.87,12.45 43.87,12.45 44.1,12.5 44.1,12.5 43.87,12.45 43.87,12.4 43.87)))')
+        self.failUnless(ref.equals_exact(Country.objects.snap_to_grid(0.05, 0.23, 0.5, 0.17).get(name='San Marino').snap_to_grid, tol))
 
 from test_feeds import GeoFeedTest
 from test_regress import GeoRegressionTests