From c9e85443211715993d7b27af2bf772380e26f6de Mon Sep 17 00:00:00 2001
From: Tim Graham <timograham@gmail.com>
Date: Wed, 11 Nov 2020 01:39:15 -0500
Subject: [PATCH] Added SpatialFeatures.unsupported_geojson_options.

---
 django/contrib/gis/db/backends/base/features.py   | 3 +++
 django/contrib/gis/db/backends/mysql/features.py  | 1 +
 django/contrib/gis/db/backends/oracle/features.py | 1 +
 tests/gis_tests/geoapp/test_functions.py          | 7 +++----
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/django/contrib/gis/db/backends/base/features.py b/django/contrib/gis/db/backends/base/features.py
index e714440e58..a88ad03684 100644
--- a/django/contrib/gis/db/backends/base/features.py
+++ b/django/contrib/gis/db/backends/base/features.py
@@ -51,6 +51,9 @@ class BaseSpatialFeatures:
     # Can SchemaEditor alter geometry fields?
     can_alter_geometry_field = True
 
+    # Set of options that AsGeoJSON() doesn't support.
+    unsupported_geojson_options = {}
+
     @property
     def supports_bbcontains_lookup(self):
         return 'bbcontains' in self.connection.ops.gis_operators
diff --git a/django/contrib/gis/db/backends/mysql/features.py b/django/contrib/gis/db/backends/mysql/features.py
index 424df28d94..63e2fa1dd3 100644
--- a/django/contrib/gis/db/backends/mysql/features.py
+++ b/django/contrib/gis/db/backends/mysql/features.py
@@ -14,6 +14,7 @@ class DatabaseFeatures(BaseSpatialFeatures, MySQLDatabaseFeatures):
     supports_transform = False
     supports_null_geometries = False
     supports_num_points_poly = False
+    unsupported_geojson_options = {'crs'}
 
     @cached_property
     def supports_empty_geometry_collection(self):
diff --git a/django/contrib/gis/db/backends/oracle/features.py b/django/contrib/gis/db/backends/oracle/features.py
index f2ed4d3076..80c71e0dcb 100644
--- a/django/contrib/gis/db/backends/oracle/features.py
+++ b/django/contrib/gis/db/backends/oracle/features.py
@@ -10,3 +10,4 @@ class DatabaseFeatures(BaseSpatialFeatures, OracleDatabaseFeatures):
     supports_geometry_field_unique_index = False
     supports_perimeter_geodetic = True
     supports_dwithin_distance_expr = False
+    unsupported_geojson_options = {'bbox', 'crs', 'precision'}
diff --git a/tests/gis_tests/geoapp/test_functions.py b/tests/gis_tests/geoapp/test_functions.py
index c2e06db4c5..b518f9cb53 100644
--- a/tests/gis_tests/geoapp/test_functions.py
+++ b/tests/gis_tests/geoapp/test_functions.py
@@ -44,14 +44,13 @@ class GISFunctionsTests(FuncTestMixin, TestCase):
             '{"type":"Point","crs":{"type":"name","properties":{"name":"EPSG:4326"}},'
             '"bbox":[-87.65018,41.85039,-87.65018,41.85039],"coordinates":[-87.65018,41.85039]}'
         )
-        # MySQL and Oracle ignore the crs option.
-        if mysql or oracle:
+        if 'crs' in connection.features.unsupported_geojson_options:
             del houston_json['crs']
             del chicago_json['crs']
-        # Oracle ignores also the bbox and precision options.
-        if oracle:
+        if 'bbox' in connection.features.unsupported_geojson_options:
             del chicago_json['bbox']
             del victoria_json['bbox']
+        if 'precision' in connection.features.unsupported_geojson_options:
             chicago_json['coordinates'] = [-87.650175, 41.850385]
 
         # Precision argument should only be an integer