Refs #33783 -- Added IsEmpty GIS database function and __isempty lookup on SpatiaLite.

Author: smithdc1

django/contrib/gis/db/backends/spatialite/operations.py

@@ -73,6 +73,7 @@ class SpatiaLiteOperations(BaseSpatialOperations, DatabaseOperations):
         "ForcePolygonCW": "ST_ForceLHR",
         "FromWKB": "ST_GeomFromWKB",
         "FromWKT": "ST_GeomFromText",
+        "IsEmpty": "ST_IsEmpty",
         "Length": "ST_Length",
         "LineLocatePoint": "ST_Line_Locate_Point",
         "NumPoints": "ST_NPoints",
@@ -84,7 +85,7 @@ class SpatiaLiteOperations(BaseSpatialOperations, DatabaseOperations):
 
     @cached_property
     def unsupported_functions(self):
-        unsupported = {"GeometryDistance", "IsEmpty", "MemSize", "Rotate"}
+        unsupported = {"GeometryDistance", "MemSize", "Rotate"}
         if not self.geom_lib_version():
             unsupported |= {"Azimuth", "GeoHash", "MakeValid"}
         if self.spatial_version < (5, 1):

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

@@ -451,6 +451,10 @@ class IsEmpty(GeoFuncMixin, Transform):
     lookup_name = "isempty"
     output_field = BooleanField()
 
+    def as_sqlite(self, compiler, connection, **extra_context):
+        sql, params = super().as_sql(compiler, connection, **extra_context)
+        return "NULLIF(%s, -1)" % sql, params
+
 
 @BaseSpatialField.register_lookup
 class IsValid(OracleToleranceMixin, GeoFuncMixin, Transform):

docs/ref/contrib/gis/db-api.txt

@@ -363,7 +363,7 @@ Lookup Type                        PostGIS    Oracle    MariaDB      MySQL [#]_
 :lookup:`exact <same_as>`          X          X         X            X            X          B
 :lookup:`geom_type`                X          X (≥ 23c) X            X            X
 :lookup:`intersects`               X          X         X            X            X          B
-:lookup:`isempty`                  X
+:lookup:`isempty`                  X                                              X
 :lookup:`isvalid`                  X          X         X (≥ 12.0.1) X            X
 :lookup:`overlaps`                 X          X         X            X            X          B
 :lookup:`relate`                   X          X         X                         X          C
@@ -414,7 +414,7 @@ Function                              PostGIS  Oracle         MariaDB      MySQL
 :class:`GeometryDistance`             X
 :class:`GeometryType`                 X        X (≥ 23c)      X            X           X
 :class:`Intersection`                 X        X              X            X           X
-:class:`IsEmpty`                      X
+:class:`IsEmpty`                      X                                                X
 :class:`IsValid`                      X        X              X (≥ 12.0.1) X           X
 :class:`Length`                       X        X              X            X           X
 :class:`LineLocatePoint`              X                                                X

docs/ref/contrib/gis/functions.txt

@@ -621,11 +621,16 @@ Miscellaneous
 
 .. class:: IsEmpty(expr)
 
-*Availability*: `PostGIS <https://postgis.net/docs/ST_IsEmpty.html>`__
+*Availability*: `PostGIS <https://postgis.net/docs/ST_IsEmpty.html>`__,
+SpatiaLite
 
 Accepts a geographic field or expression and tests if the value is an empty
 geometry. Returns ``True`` if its value is empty and ``False`` otherwise.
 
+.. versionchanged:: 6.1
+
+    SpatiaLite support was added.
+
 ``IsValid``
 -----------
 

docs/ref/contrib/gis/geoquerysets.txt

@@ -361,14 +361,19 @@ SpatiaLite  ``Intersects(poly, geom)``
 ``isempty``
 -----------
 
-*Availability*: `PostGIS <https://postgis.net/docs/ST_IsEmpty.html>`__
+*Availability*: `PostGIS <https://postgis.net/docs/ST_IsEmpty.html>`__,
+SpatiaLite
 
 Tests if the geometry is empty.
 
 Example::
 
     Zipcode.objects.filter(poly__isempty=True)
 
+.. versionchanged:: 6.1
+
+    SpatiaLite support was added.
+
 .. fieldlookup:: isvalid
 
 ``isvalid``

docs/releases/6.1.txt

@@ -53,7 +53,9 @@ Minor features
 :mod:`django.contrib.gis`
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 
-* ...
+* The :lookup:`isempty` lookup and
+  :class:`IsEmpty() <django.contrib.gis.db.models.functions.IsEmpty>`
+  database function are now supported on SpatiaLite.
 
 :mod:`django.contrib.messages`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tests/gis_tests/geoapp/test_functions.py

@@ -431,7 +431,7 @@ def test_intersection(self):
                 self.assertIs(c.inter.empty, True)
 
     @skipUnlessDBFeature("supports_empty_geometries", "has_IsEmpty_function")
-    def test_isempty(self):
+    def test_isempty_geometry_empty(self):
         empty = City.objects.create(name="Nowhere", point=Point(srid=4326))
         City.objects.create(name="Somewhere", point=Point(6.825, 47.1, srid=4326))
         self.assertSequenceEqual(
@@ -442,6 +442,18 @@ def test_isempty(self):
         )
         self.assertSequenceEqual(City.objects.filter(point__isempty=True), [empty])
 
+    @skipUnlessDBFeature("has_IsEmpty_function")
+    def test_isempty_geometry_null(self):
+        nowhere = State.objects.create(name="Nowhere", poly=None)
+        qs = State.objects.annotate(isempty=functions.IsEmpty("poly"))
+        self.assertSequenceEqual(qs.filter(isempty=None), [nowhere])
+        self.assertSequenceEqual(
+            qs.filter(isempty=False).order_by("name").values_list("name", flat=True),
+            ["Colorado", "Kansas"],
+        )
+        self.assertSequenceEqual(qs.filter(isempty=True), [])
+        self.assertSequenceEqual(State.objects.filter(poly__isempty=True), [])
+
     @skipUnlessDBFeature("has_IsValid_function")
     def test_isvalid(self):
         valid_geom = fromstr("POLYGON((0 0, 0 1, 1 1, 1 0, 0 0))")