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Added Spatialite support to GIS functions

This commit is contained in:
Claude Paroz 2015-01-23 22:45:57 +01:00
parent d9ff5ef36d
commit 44bdbbc316
5 changed files with 91 additions and 12 deletions
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3
django/contrib/gis/db/backends/base/features.py
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@ -26,8 +26,9 @@ class BaseSpatialFeatures(object):
supports_real_shape_operations = True
# Can geometry fields be null?
supports_null_geometries = True
# Can the `distance` GeoQuerySet method be applied on geodetic coordinate systems?
# Can the `distance`/`length` functions be applied on geodetic coordinate systems?
supports_distance_geodetic = True
supports_length_geodetic = True
# Is the database able to count vertices on polygons (with `num_points`)?
supports_num_points_poly = True

21
django/contrib/gis/db/backends/spatialite/operations.py
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@ -1,3 +1,9 @@
"""
SQL functions reference lists:
http://www.gaia-gis.it/spatialite-2.4.0/spatialite-sql-2.4.html
http://www.gaia-gis.it/spatialite-3.0.0-BETA/spatialite-sql-3.0.0.html
http://www.gaia-gis.it/gaia-sins/spatialite-sql-4.2.1.html
"""
import re
import sys
@ -74,6 +80,21 @@ class SpatiaLiteOperations(BaseSpatialOperations, DatabaseOperations):
'distance_lte': SpatialOperator(func='Distance', op='<='),
}
function_names = {
'Length': 'ST_Length',
'Reverse': 'ST_Reverse',
'Scale': 'ScaleCoords',
'Translate': 'ST_Translate',
'Union': 'ST_Union',
}
@cached_property
def unsupported_functions(self):
unsupported = {'BoundingCircle', 'ForceRHR', 'GeoHash', 'MemSize'}
if self.spatial_version < (4, 0, 0):
unsupported.add('Reverse')
return unsupported
@cached_property
def spatial_version(self):
"""Determine the version of the SpatiaLite library."""

51
django/contrib/gis/db/models/functions.py
View File

@ -79,6 +79,9 @@ class GeomValue(Value):
self.value = connection.ops.Adapter(self.value)
return super(GeomValue, self).as_sql(compiler, connection)
def as_sqlite(self, compiler, connection):
return 'GeomFromText(%%s, %s)' % self.srid, [connection.ops.Adapter(self.value)]
class GeoFuncWithGeoParam(GeoFunc):
def __init__(self, expression, geom, *expressions, **extra):
@ -94,6 +97,18 @@ class GeoFuncWithGeoParam(GeoFunc):
super(GeoFuncWithGeoParam, self).__init__(expression, geom, *expressions, **extra)
class SQLiteDecimalToFloatMixin(object):
"""
By default, Decimal values are converted to str by the SQLite backend, which
is not acceptable by the GIS functions expecting numeric values.
"""
def as_sqlite(self, compiler, connection):
for expr in self.get_source_expressions():
if hasattr(expr, 'value') and isinstance(expr.value, Decimal):
expr.value = float(expr.value)
return super(SQLiteDecimalToFloatMixin, self).as_sql(compiler, connection)
class Area(GeoFunc):
def as_sql(self, compiler, connection):
if connection.ops.oracle:
@ -143,7 +158,10 @@ class AsGML(GeoFunc):
class AsKML(AsGML):
pass
def as_sqlite(self, compiler, connection):
# No version parameter
self.source_expressions.pop(0)
return super(AsKML, self).as_sql(compiler, connection)
class AsSVG(GeoFunc):
@ -261,6 +279,15 @@ class Length(DistanceResultMixin, GeoFunc):
self.function = connection.ops.length3d
return super(Length, self).as_sql(compiler, connection)
def as_sqlite(self, compiler, connection):
geo_field = GeometryField(srid=self.srid)
if geo_field.geodetic(connection):
if self.spheroid:
self.function = 'GeodesicLength'
else:
self.function = 'GreatCircleLength'
return super(Length, self).as_sql(compiler, connection)
class MemSize(GeoFunc):
output_field_class = IntegerField
@ -273,6 +300,11 @@ class NumGeometries(GeoFunc):
class NumPoints(GeoFunc):
output_field_class = IntegerField
def as_sqlite(self, compiler, connection):
if self.source_expressions[self.geom_param_pos].output_field.geom_type != 'LINESTRING':
raise TypeError("Spatialite NumPoints can only operate on LineString content")
return super(NumPoints, self).as_sql(compiler, connection)
class Perimeter(DistanceResultMixin, GeoFunc):
output_field_class = FloatField
@ -292,7 +324,7 @@ class Reverse(GeoFunc):
pass
class Scale(GeoFunc):
class Scale(SQLiteDecimalToFloatMixin, GeoFunc):
def __init__(self, expression, x, y, z=0.0, **extra):
expressions = [
expression,
@ -304,7 +336,7 @@ class Scale(GeoFunc):
super(Scale, self).__init__(*expressions, **extra)
class SnapToGrid(GeoFunc):
class SnapToGrid(SQLiteDecimalToFloatMixin, GeoFunc):
def __init__(self, expression, *args, **extra):
nargs = len(args)
expressions = [expression]
@ -342,9 +374,20 @@ class Transform(GeoFunc):
# Make srid the resulting srid of the transformation
return self.source_expressions[self.geom_param_pos + 1].value
def convert_value(self, value, expression, connection, context):
value = super(Transform, self).convert_value(value, expression, connection, context)
if not connection.ops.postgis and not value.srid:
# Some backends do not set the srid on the returning geometry
value.srid = self.srid
return value
class Translate(Scale):
pass
def as_sqlite(self, compiler, connection):
# Always provide the z parameter
if len(self.source_expressions) < 4:
self.source_expressions.append(Value(0))
return super(Translate, self).as_sqlite(compiler, connection)
class Union(GeoFuncWithGeoParam):

6
tests/gis_tests/distapp/tests.py
View File

@ -617,13 +617,15 @@ class DistanceFunctionsTests(TestCase):
len_m1 = 473504.769553813
len_m2 = 4617.668
if connection.features.supports_distance_geodetic:
if connection.features.supports_length_geodetic:
qs = Interstate.objects.annotate(length=Length('path'))
tol = 2 if oracle else 3
self.assertAlmostEqual(len_m1, qs[0].length.m, tol)
# TODO: test with spheroid argument (True and False)
else:
# Does not support geodetic coordinate systems.
self.assertRaises(ValueError, Interstate.objects.annotate(length=Length('path')))
with self.assertRaises(ValueError):
Interstate.objects.annotate(length=Length('path'))
# Now doing length on a projected coordinate system.
i10 = SouthTexasInterstate.objects.annotate(length=Length('path')).get(name='I-10')

22
tests/gis_tests/geoapp/test_functions.py
View File

@ -172,15 +172,22 @@ class GISFunctionsTests(TestCase):
@skipUnlessDBFeature("has_Difference_function")
def test_difference(self):
geom = Point(5, 23, srid=4326)
qs = Country.objects.annotate(difference=functions.Difference('mpoly', geom))
qs = Country.objects.annotate(diff=functions.Difference('mpoly', geom))
# For some reason SpatiaLite does something screwy with the Texas geometry here.
if spatialite:
qs = qs.exclude(name='Texas')
for c in qs:
self.assertEqual(c.mpoly.difference(geom), c.difference)
self.assertEqual(c.mpoly.difference(geom), c.diff)
@skipUnlessDBFeature("has_Difference_function")
def test_difference_mixed_srid(self):
"""Testing with mixed SRID (Country has default 4326)."""
geom = Point(556597.4, 2632018.6, srid=3857) # Spherical mercator
qs = Country.objects.annotate(difference=functions.Difference('mpoly', geom))
# For some reason SpatiaLite does something screwy with the Texas geometry here.
if spatialite:
qs = qs.exclude(name='Texas')
for c in qs:
self.assertEqual(c.mpoly.difference(geom), c.difference)
@ -220,7 +227,12 @@ class GISFunctionsTests(TestCase):
geom = Point(5, 23, srid=4326)
qs = Country.objects.annotate(inter=functions.Intersection('mpoly', geom))
for c in qs:
self.assertEqual(c.mpoly.intersection(geom), c.inter)
if spatialite:
# When the intersection is empty, Spatialite returns None
expected = None
else:
expected = c.mpoly.intersection(geom)
self.assertEqual(c.inter, expected)
@skipUnlessDBFeature("has_MemSize_function")
def test_memsize(self):
@ -416,8 +428,8 @@ class GISFunctionsTests(TestCase):
union=functions.Union('mpoly', geom),
)
# XXX For some reason SpatiaLite does something screwey with the Texas geometry here. Also,
# XXX it doesn't like the null intersection.
# For some reason SpatiaLite does something screwey with the Texas geometry here.
# Also, it doesn't like the null intersection.
if spatialite:
qs = qs.exclude(name='Texas')
else: