Fixed #26455 -- Allowed filtering and repairing invalid geometries.

Added the IsValid and MakeValid database functions, and the isvalid lookup,
all for PostGIS.

Thanks Tim Graham for the review.

14 files changed, 121 insertions, 17 deletions

diff --git a/django/contrib/gis/db/backends/base/features.py b/django/contrib/gis/db/backends/base/features.py
index 027baa5575..451b515625 100644
--- a/django/contrib/gis/db/backends/base/features.py
+++ b/django/contrib/gis/db/backends/base/features.py
@@ -64,6 +64,10 @@ class BaseSpatialFeatures(object):
     def supports_relate_lookup(self):
         return 'relate' in self.connection.ops.gis_operators
 
+    @property
+    def supports_isvalid_lookup(self):
+        return 'isvalid' in self.connection.ops.gis_operators
+
     # For each of those methods, the class will have a property named
     # `has_<name>_method` (defined in __init__) which accesses connection.ops
     # to determine GIS method availability.
diff --git a/django/contrib/gis/db/backends/base/operations.py b/django/contrib/gis/db/backends/base/operations.py
index 5dafae760d..8fc51da84a 100644
--- a/django/contrib/gis/db/backends/base/operations.py
+++ b/django/contrib/gis/db/backends/base/operations.py
@@ -58,10 +58,10 @@ class BaseSpatialOperations(object):
     unsupported_functions = {
         'Area', 'AsGeoJSON', 'AsGML', 'AsKML', 'AsSVG',
         'BoundingCircle', 'Centroid', 'Difference', 'Distance', 'Envelope',
-        'ForceRHR', 'GeoHash', 'Intersection', 'Length', 'MemSize', 'NumGeometries',
-        'NumPoints', 'Perimeter', 'PointOnSurface', 'Reverse', 'Scale',
-        'SnapToGrid', 'SymDifference', 'Transform', 'Translate',
-        'Union',
+        'ForceRHR', 'GeoHash', 'Intersection', 'IsValid', 'Length', 'MakeValid',
+        'MemSize', 'NumGeometries', 'NumPoints', 'Perimeter', 'PointOnSurface',
+        'Reverse', 'Scale', 'SnapToGrid', 'SymDifference', 'Transform',
+        'Translate', 'Union',
     }
 
     # Serialization
diff --git a/django/contrib/gis/db/backends/mysql/operations.py b/django/contrib/gis/db/backends/mysql/operations.py
index 3aedc24040..df4ba36b49 100644
--- a/django/contrib/gis/db/backends/mysql/operations.py
+++ b/django/contrib/gis/db/backends/mysql/operations.py
@@ -67,7 +67,7 @@ class MySQLOperations(BaseSpatialOperations, DatabaseOperations):
     def unsupported_functions(self):
         unsupported = {
             'AsGeoJSON', 'AsGML', 'AsKML', 'AsSVG', 'BoundingCircle',
-            'ForceRHR', 'GeoHash', 'MemSize',
+            'ForceRHR', 'GeoHash', 'IsValid', 'MakeValid', 'MemSize',
             'Perimeter', 'PointOnSurface', 'Reverse', 'Scale', 'SnapToGrid',
             'Transform', 'Translate',
         }
diff --git a/django/contrib/gis/db/backends/oracle/operations.py b/django/contrib/gis/db/backends/oracle/operations.py
index 2404cf9bc4..2a166f23a1 100644
--- a/django/contrib/gis/db/backends/oracle/operations.py
+++ b/django/contrib/gis/db/backends/oracle/operations.py
@@ -127,7 +127,7 @@ class OracleOperations(BaseSpatialOperations, DatabaseOperations):
     unsupported_functions = {
         'AsGeoJSON', 'AsGML', 'AsKML', 'AsSVG',
         'BoundingCircle', 'Envelope',
-        'ForceRHR', 'GeoHash', 'MemSize', 'Scale',
+        'ForceRHR', 'GeoHash', 'IsValid', 'MakeValid', 'MemSize', 'Scale',
         'SnapToGrid', 'Translate',
     }
 
diff --git a/django/contrib/gis/db/backends/postgis/operations.py b/django/contrib/gis/db/backends/postgis/operations.py
index 4c3ba8ca50..89ddc11127 100644
--- a/django/contrib/gis/db/backends/postgis/operations.py
+++ b/django/contrib/gis/db/backends/postgis/operations.py
@@ -79,6 +79,7 @@ class PostGISOperations(BaseSpatialOperations, DatabaseOperations):
         'disjoint': PostGISOperator(func='ST_Disjoint'),
         'equals': PostGISOperator(func='ST_Equals'),
         'intersects': PostGISOperator(func='ST_Intersects', geography=True),
+        'isvalid': PostGISOperator(func='ST_IsValid'),
         'overlaps': PostGISOperator(func='ST_Overlaps'),
         'relate': PostGISOperator(func='ST_Relate'),
         'touches': PostGISOperator(func='ST_Touches'),
@@ -118,11 +119,13 @@ class PostGISOperations(BaseSpatialOperations, DatabaseOperations):
         self.geojson = prefix + 'AsGeoJson'
         self.gml = prefix + 'AsGML'
         self.intersection = prefix + 'Intersection'
+        self.isvalid = prefix + 'IsValid'
         self.kml = prefix + 'AsKML'
         self.length = prefix + 'Length'
         self.length3d = prefix + '3DLength'
         self.length_spheroid = prefix + 'length_spheroid'
         self.makeline = prefix + 'MakeLine'
+        self.makevalid = prefix + 'MakeValid'
         self.mem_size = prefix + 'mem_size'
         self.num_geom = prefix + 'NumGeometries'
         self.num_points = prefix + 'npoints'
diff --git a/django/contrib/gis/db/backends/spatialite/operations.py b/django/contrib/gis/db/backends/spatialite/operations.py
index f551b67bc6..f2f516109a 100644
--- a/django/contrib/gis/db/backends/spatialite/operations.py
+++ b/django/contrib/gis/db/backends/spatialite/operations.py
@@ -96,7 +96,7 @@ class SpatiaLiteOperations(BaseSpatialOperations, DatabaseOperations):
 
     @cached_property
     def unsupported_functions(self):
-        unsupported = {'BoundingCircle', 'ForceRHR', 'MemSize'}
+        unsupported = {'BoundingCircle', 'ForceRHR', 'IsValid', 'MakeValid', 'MemSize'}
         if self.spatial_version < (3, 1, 0):
             unsupported.add('SnapToGrid')
         if self.spatial_version < (4, 0, 0):
diff --git a/django/contrib/gis/db/models/fields.py b/django/contrib/gis/db/models/fields.py
index 80fe8628ce..49d86f7618 100644
--- a/django/contrib/gis/db/models/fields.py
+++ b/django/contrib/gis/db/models/fields.py
@@ -225,7 +225,7 @@ class GeometryField(GeoSelectFormatMixin, BaseSpatialField):
         returning to the caller.
         """
         value = super(GeometryField, self).get_prep_value(value)
-        if isinstance(value, Expression):
+        if isinstance(value, (Expression, bool)):
             return value
         elif isinstance(value, (tuple, list)):
             geom = value[0]
diff --git a/django/contrib/gis/db/models/functions.py b/django/contrib/gis/db/models/functions.py
index 4f76c155f2..7355bbcbfc 100644
--- a/django/contrib/gis/db/models/functions.py
+++ b/django/contrib/gis/db/models/functions.py
@@ -6,7 +6,7 @@ from django.contrib.gis.measure import (
     Area as AreaMeasure, Distance as DistanceMeasure,
 )
 from django.core.exceptions import FieldError
-from django.db.models import FloatField, IntegerField, TextField
+from django.db.models import BooleanField, FloatField, IntegerField, TextField
 from django.db.models.expressions import Func, Value
 from django.utils import six
 
@@ -282,6 +282,10 @@ class Intersection(OracleToleranceMixin, GeoFuncWithGeoParam):
     arity = 2
 
 
+class IsValid(GeoFunc):
+    output_field_class = BooleanField
+
+
 class Length(DistanceResultMixin, OracleToleranceMixin, GeoFunc):
     output_field_class = FloatField
 
@@ -319,6 +323,10 @@ class Length(DistanceResultMixin, OracleToleranceMixin, GeoFunc):
         return super(Length, self).as_sql(compiler, connection)
 
 
+class MakeValid(GeoFunc):
+    pass
+
+
 class MemSize(GeoFunc):
     output_field_class = IntegerField
     arity = 1
diff --git a/django/contrib/gis/db/models/lookups.py b/django/contrib/gis/db/models/lookups.py
index a1c85b9bfe..158fb5cfa1 100644
--- a/django/contrib/gis/db/models/lookups.py
+++ b/django/contrib/gis/db/models/lookups.py
@@ -5,7 +5,7 @@ import re
 from django.core.exceptions import FieldDoesNotExist
 from django.db.models.constants import LOOKUP_SEP
 from django.db.models.expressions import Col, Expression
-from django.db.models.lookups import Lookup
+from django.db.models.lookups import BuiltinLookup, Lookup
 from django.utils import six
 
 gis_lookups = {}
@@ -270,6 +270,19 @@ class IntersectsLookup(GISLookup):
 gis_lookups['intersects'] = IntersectsLookup
 
 
+class IsValidLookup(BuiltinLookup):
+    lookup_name = 'isvalid'
+
+    def as_sql(self, compiler, connection):
+        gis_op = connection.ops.gis_operators[self.lookup_name]
+        sql, params = self.process_lhs(compiler, connection)
+        sql = '%(func)s(%(lhs)s)' % {'func': gis_op.func, 'lhs': sql}
+        if not self.rhs:
+            sql = 'NOT ' + sql
+        return sql, params
+gis_lookups['isvalid'] = IsValidLookup
+
+
 class OverlapsLookup(GISLookup):
     lookup_name = 'overlaps'
 gis_lookups['overlaps'] = OverlapsLookup
diff --git a/docs/ref/contrib/gis/functions.txt b/docs/ref/contrib/gis/functions.txt
index 04da9e78af..00dee42c57 100644
--- a/docs/ref/contrib/gis/functions.txt
+++ b/docs/ref/contrib/gis/functions.txt
@@ -25,13 +25,12 @@ Function's summary:
 ==================  =======================   ======================  ===================  ==================  =====================
 Measurement         Relationships             Operations              Editors              Output format       Miscellaneous
 ==================  =======================   ======================  ===================  ==================  =====================
-:class:`Area`       :class:`BoundingCircle`   :class:`Difference`     :class:`ForceRHR`    :class:`AsGeoJSON`  :class:`MemSize`
-:class:`Distance`   :class:`Centroid`         :class:`Intersection`   :class:`Reverse`     :class:`AsGML`      :class:`NumGeometries`
-:class:`Length`     :class:`Envelope`         :class:`SymDifference`  :class:`Scale`       :class:`AsKML`      :class:`NumPoints`
-:class:`Perimeter`  :class:`PointOnSurface`   :class:`Union`          :class:`SnapToGrid`  :class:`AsSVG`
-
-                                                                      :class:`Transform`   :class:`GeoHash`
-
+:class:`Area`       :class:`BoundingCircle`   :class:`Difference`     :class:`ForceRHR`    :class:`AsGeoJSON`  :class:`IsValid`
+:class:`Distance`   :class:`Centroid`         :class:`Intersection`   :class:`MakeValid`   :class:`AsGML`      :class:`MemSize`
+:class:`Length`     :class:`Envelope`         :class:`SymDifference`  :class:`Reverse`     :class:`AsKML`      :class:`NumGeometries`
+:class:`Perimeter`  :class:`PointOnSurface`   :class:`Union`          :class:`Scale`       :class:`AsSVG`      :class:`NumPoints`
+                                                                      :class:`SnapToGrid`  :class:`GeoHash`
+                                                                      :class:`Transform`
                                                                       :class:`Translate`
 ==================  =======================   ======================  ===================  ==================  =====================
 
@@ -291,6 +290,18 @@ intersection between them.
 
     MySQL support was added.
 
+``IsValid``
+===========
+
+.. class:: IsValid(expr)
+
+.. versionadded:: 1.10
+
+*Availability*: PostGIS
+
+Accepts a geographic field or expression and tests if the value is well formed.
+Returns ``True`` if its value is a valid geometry and ``False`` otherwise.
+
 ``Length``
 ==========
 
@@ -308,6 +319,20 @@ specify if the calculation should be based on a simple sphere (less
 accurate, less resource-intensive) or on a spheroid (more accurate, more
 resource-intensive) with the ``spheroid`` keyword argument.
 
+``MakeValid``
+=============
+
+.. class:: MakeValid(expr)
+
+.. versionadded:: 1.10
+
+*Availability*: PostGIS
+
+Accepts a geographic field or expression and attempts to convert the value into
+a valid geometry without losing any of the input vertices. Geometries that are
+already valid are returned without changes. Simple polygons might become a
+multipolygon and the result might be of lower dimension than the input.
+
 ``MemSize``
 ===========
 
diff --git a/docs/ref/contrib/gis/geoquerysets.txt b/docs/ref/contrib/gis/geoquerysets.txt
index ed142d72b8..6b12c07a57 100644
--- a/docs/ref/contrib/gis/geoquerysets.txt
+++ b/docs/ref/contrib/gis/geoquerysets.txt
@@ -247,6 +247,25 @@ MySQL       ``MBRIntersects(poly, geom)``
 SpatiaLite  ``Intersects(poly, geom)``
 ==========  =================================================
 
+.. fieldlookup:: isvalid
+
+``isvalid``
+-----------
+
+.. versionadded:: 1.10
+
+*Availability*: PostGIS
+
+Tests if the geometry is valid.
+
+Example::
+
+    Zipcode.objects.filter(poly__isvalid=True)
+
+PostGIS equivalent::
+
+    SELECT ... WHERE ST_IsValid(poly)
+
 .. fieldlookup:: overlaps
 
 ``overlaps``
diff --git a/docs/releases/1.10.txt b/docs/releases/1.10.txt
index 2e97ff3d54..490aa30fb7 100644
--- a/docs/releases/1.10.txt
+++ b/docs/releases/1.10.txt
@@ -147,6 +147,12 @@ Minor features
   <django.contrib.gis.gdal.GDALBand.data>` method was added. Band data can
   now be updated with repeated values efficiently.
 
+* Added database functions
+  :class:`~django.contrib.gis.db.models.functions.IsValid` and
+  :class:`~django.contrib.gis.db.models.functions.MakeValid`, as well as the
+  :lookup:`isvalid` lookup, all for PostGIS. This allows filtering and
+  repairing invalid geometries on the database side.
+
 :mod:`django.contrib.messages`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/tests/gis_tests/geoapp/test_functions.py b/tests/gis_tests/geoapp/test_functions.py
index 344fa03e61..c42ed95a86 100644
--- a/tests/gis_tests/geoapp/test_functions.py
+++ b/tests/gis_tests/geoapp/test_functions.py
@@ -233,6 +233,17 @@ class GISFunctionsTests(TestCase):
                 expected = c.mpoly.intersection(geom)
             self.assertEqual(c.inter, expected)
 
+    @skipUnlessDBFeature("has_IsValid_function")
+    def test_isvalid(self):
+        valid_geom = fromstr('POLYGON((0 0, 0 1, 1 1, 1 0, 0 0))')
+        invalid_geom = fromstr('POLYGON((0 0, 0 1, 1 1, 1 0, 1 1, 1 0, 0 0))')
+        State.objects.create(name='valid', poly=valid_geom)
+        State.objects.create(name='invalid', poly=invalid_geom)
+        valid = State.objects.filter(name='valid').annotate(isvalid=functions.IsValid('poly')).first()
+        invalid = State.objects.filter(name='invalid').annotate(isvalid=functions.IsValid('poly')).first()
+        self.assertEqual(valid.isvalid, True)
+        self.assertEqual(invalid.isvalid, False)
+
     @skipUnlessDBFeature("has_Area_function")
     def test_area_with_regular_aggregate(self):
         # Create projected country objects, for this test to work on all backends.
@@ -249,6 +260,14 @@ class GISFunctionsTests(TestCase):
                 result = result.sq_m
             self.assertAlmostEqual((result - c.mpoly.area) / c.mpoly.area, 0)
 
+    @skipUnlessDBFeature("has_MakeValid_function")
+    def test_make_valid(self):
+        invalid_geom = fromstr('POLYGON((0 0, 0 1, 1 1, 1 0, 1 1, 1 0, 0 0))')
+        State.objects.create(name='invalid', poly=invalid_geom)
+        invalid = State.objects.filter(name='invalid').annotate(repaired=functions.MakeValid('poly')).first()
+        self.assertEqual(invalid.repaired.valid, True)
+        self.assertEqual(invalid.repaired, fromstr('POLYGON((0 0, 0 1, 1 1, 1 0, 0 0))'))
+
     @skipUnlessDBFeature("has_MemSize_function")
     def test_memsize(self):
         ptown = City.objects.annotate(size=functions.MemSize('point')).get(name='Pueblo')
diff --git a/tests/gis_tests/geoapp/tests.py b/tests/gis_tests/geoapp/tests.py
index f0b6f7ba65..2b215f80a9 100644
--- a/tests/gis_tests/geoapp/tests.py
+++ b/tests/gis_tests/geoapp/tests.py
@@ -300,6 +300,13 @@ class GeoLookupTest(TestCase):
             0
         )
 
+    @skipUnlessDBFeature("supports_isvalid_lookup")
+    def test_isvalid_lookup(self):
+        invalid_geom = fromstr('POLYGON((0 0, 0 1, 1 1, 1 0, 1 1, 1 0, 0 0))')
+        State.objects.create(name='invalid', poly=invalid_geom)
+        self.assertEqual(State.objects.filter(poly__isvalid=False).count(), 1)
+        self.assertEqual(State.objects.filter(poly__isvalid=True).count(), State.objects.count() - 1)
+
     @skipUnlessDBFeature("supports_left_right_lookups")
     def test_left_right_lookups(self):
         "Testing the 'left' and 'right' lookup types."