Refs #35783 -- Added NumDimensions geographic database function.

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

@@ -57,6 +57,7 @@ class BaseSpatialOperations:
         "LineLocatePoint",
         "MakeValid",
         "MemSize",
+        "NumDimensions",
         "NumGeometries",
         "NumPoints",
         "Perimeter",

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

@@ -100,6 +100,7 @@ class MySQLOperations(BaseSpatialOperations, DatabaseOperations):
             "LineLocatePoint",
             "MakeValid",
             "MemSize",
+            "NumDimensions",
             "Perimeter",
             "PointOnSurface",
             "Reverse",

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

@@ -129,6 +129,7 @@ class OracleOperations(BaseSpatialOperations, DatabaseOperations):
         "LineLocatePoint",
         "MakeValid",
         "MemSize",
+        "NumDimensions",
         "Scale",
         "SnapToGrid",
         "Translate",

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

@@ -176,6 +176,7 @@ class PostGISOperations(BaseSpatialOperations, DatabaseOperations):
             "BoundingCircle": "ST_MinimumBoundingCircle",
             "FromWKB": "ST_GeomFromWKB",
             "FromWKT": "ST_GeomFromText",
+            "NumDimensions": "ST_NDims",
             "NumPoints": "ST_NPoints",
         }
         return function_names

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

@@ -73,6 +73,7 @@ class SpatiaLiteOperations(BaseSpatialOperations, DatabaseOperations):
         "FromWKT": "ST_GeomFromText",
         "Length": "ST_Length",
         "LineLocatePoint": "ST_Line_Locate_Point",
+        "NumDimensions": "ST_NDims",
         "NumPoints": "ST_NPoints",
         "Reverse": "ST_Reverse",
         "Scale": "ScaleCoords",

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

@@ -491,6 +491,11 @@ class MemSize(GeoFunc):
     arity = 1
 
 
+class NumDimensions(GeoFunc):
+    output_field = IntegerField()
+    arity = 1
+
+
 class NumGeometries(GeoFunc):
     output_field = IntegerField()
     arity = 1

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

@@ -414,6 +414,7 @@ Function                              PostGIS  Oracle         MariaDB      MySQL
 :class:`LineLocatePoint`              X                                                X
 :class:`MakeValid`                    X                                                X (LWGEOM/RTTOPO)
 :class:`MemSize`                      X
+:class:`NumDimensions`                X                                                X
 :class:`NumGeometries`                X        X              X            X           X
 :class:`NumPoints`                    X        X              X            X           X
 :class:`Perimeter`                    X        X                                       X

docs/ref/contrib/gis/functions.txt

@@ -28,9 +28,9 @@ Measurement                Relationships             Operations              Edi
 :class:`Area`              :class:`Azimuth`          :class:`Difference`     :class:`ForcePolygonCW`                      :class:`AsGeoJSON`  :class:`IsEmpty`
 :class:`Distance`          :class:`BoundingCircle`   :class:`Intersection`   :class:`MakeValid`                           :class:`AsGML`      :class:`IsValid`
 :class:`GeometryDistance`  :class:`Centroid`         :class:`SymDifference`  :class:`Reverse`                             :class:`AsKML`      :class:`MemSize`
-:class:`Length`            :class:`ClosestPoint`     :class:`Union`          :class:`Scale`                               :class:`AsSVG`      :class:`NumGeometries`
+:class:`Length`            :class:`ClosestPoint`     :class:`Union`          :class:`Scale`                               :class:`AsSVG`      :class:`NumDimensions`
-:class:`Perimeter`         :class:`Envelope`                                 :class:`SnapToGrid`      :class:`FromWKB`    :class:`AsWKB`      :class:`NumPoints`
+:class:`Perimeter`         :class:`Envelope`                                 :class:`SnapToGrid`      :class:`FromWKB`    :class:`AsWKB`      :class:`NumGeometries`
-                           :class:`LineLocatePoint`                          :class:`Transform`       :class:`FromWKT`    :class:`AsWKT`
+                           :class:`LineLocatePoint`                          :class:`Transform`       :class:`FromWKT`    :class:`AsWKT`      :class:`NumPoints`
                            :class:`PointOnSurface`                           :class:`Translate`                           :class:`GeoHash`
 =========================  ========================  ======================  =======================  ==================  ==================  ======================
 
@@ -513,6 +513,19 @@ multipolygon and the result might be of lower dimension than the input.
 Accepts a single geographic field or expression and returns the memory size
 (number of bytes) that the geometry field takes.
 
+``NumDimensions``
+=================
+
+.. class:: NumDimensions(expression, **extra)
+
+.. versionadded:: 5.2
+
+*Availability*: `PostGIS <https://postgis.net/docs/ST_NDims.html>`__,
+SpatiaLite
+
+Accepts a single geometry field or expression and returns the number of
+dimensions used by the geometry.
+
 ``NumGeometries``
 =================
 

docs/releases/5.2.txt

@@ -132,6 +132,10 @@ Minor features
   :class:`~django.contrib.gis.db.models.functions.IsValid` database functions
   are now supported on MariaDB 11.7+.
 
+* :class:`~django.contrib.gis.db.models.functions.NumDimensions` was added for
+  PostGIS and SpatiaLite backends which returns the number of dimensions used
+  by a geometry.
+
 :mod:`django.contrib.messages`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

tests/gis_tests/geoapp/test_functions.py

@@ -11,7 +11,15 @@ from django.db.models import IntegerField, Sum, Value
 from django.test import TestCase, skipUnlessDBFeature
 
 from ..utils import FuncTestMixin
-from .models import City, Country, CountryWebMercator, ManyPointModel, State, Track
+from .models import (
+    City,
+    Country,
+    CountryWebMercator,
+    ManyPointModel,
+    State,
+    ThreeDimensionalFeature,
+    Track,
+)
 
 
 class GISFunctionsTests(FuncTestMixin, TestCase):
@@ -576,6 +584,23 @@ class GISFunctionsTests(FuncTestMixin, TestCase):
             else:
                 self.assertEqual(1, city.num_geom)
 
+    @skipUnlessDBFeature("has_NumDimensions_function")
+    def test_num_dimensions(self):
+        for c in Country.objects.annotate(num_dims=functions.NumDimensions("mpoly")):
+            self.assertEqual(2, c.num_dims)
+
+        ThreeDimensionalFeature.objects.create(
+            name="London", geom=Point(-0.126418, 51.500832, 0)
+        )
+        qs = ThreeDimensionalFeature.objects.annotate(
+            num_dims=functions.NumDimensions("geom")
+        )
+        self.assertEqual(qs[0].num_dims, 3)
+
+        msg = "'NumDimensions' takes exactly 1 argument (2 given)"
+        with self.assertRaisesMessage(TypeError, msg):
+            Country.objects.annotate(num_dims=functions.NumDimensions("point", "error"))
+
     @skipUnlessDBFeature("has_NumPoint_function")
     def test_num_points(self):
         coords = [(-95.363151, 29.763374), (-95.448601, 29.713803)]