GeoJSON reader: accept a {"type": "Polygon","coordinates": []} as a r…

…epresentation of POLYGON EMPTY (fixes duckdb/duckdb-spatial#273) This was what we exported already, which also happens to validate against http://geojson.org/schema/Polygon.json but on import, we insisted on havin a [[]] coordinates array (which does not validate the schema)
OSGeo · Mar 9, 2024 · c7e2ca8 · c7e2ca8
1 parent bd9f525
commit c7e2ca8
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Showing 2 changed files with 14 additions and 9 deletions.
diff --git a/autotest/ogr/ogr_geojson.py b/autotest/ogr/ogr_geojson.py
@@ -1906,7 +1906,7 @@ def test_ogr_geojson_50():
 
 
 ###############################################################################
-# Test writing empty geometries
+# Test writing and reading empty geometries
 
 
 def test_ogr_geojson_51():
@@ -1949,8 +1949,6 @@ def test_ogr_geojson_51():
     data = gdal.VSIFReadL(1, 10000, fp).decode("ascii")
     gdal.VSIFCloseL(fp)
 
-    gdal.Unlink("/vsimem/ogr_geojson_51.json")
-
     assert '{ "id": 1 }, "geometry": null' in data
 
     assert (
@@ -1982,6 +1980,14 @@ def test_ogr_geojson_51():
         in data
     )
 
+    ds = ogr.Open("/vsimem/ogr_geojson_51.json")
+    lyr = ds.GetLayer(0)
+    for f in lyr:
+        if f.GetFID() >= 2:
+            assert f.GetGeometryRef().IsEmpty()
+
+    gdal.Unlink("/vsimem/ogr_geojson_51.json")
+
 
 ###############################################################################
 # Test NULL type detection

diff --git a/ogr/ogrsf_frmts/geojson/ogrgeojsonreader.cpp b/ogr/ogrsf_frmts/geojson/ogrgeojsonreader.cpp
@@ -2952,7 +2952,6 @@ OGRPolygon *OGRGeoJSONReadPolygon(json_object *poObj, bool bRaw)
             if (poObjPoints == nullptr)
             {
                 poPolygon = new OGRPolygon();
-                poPolygon->addRingDirectly(new OGRLinearRing());
             }
             else
             {
@@ -2968,11 +2967,7 @@ OGRPolygon *OGRGeoJSONReadPolygon(json_object *poObj, bool bRaw)
                  i < nRings && nullptr != poPolygon; ++i)
             {
                 poObjPoints = json_object_array_get_idx(poObjRings, i);
-                if (poObjPoints == nullptr)
-                {
-                    poPolygon->addRingDirectly(new OGRLinearRing());
-                }
-                else
+                if (poObjPoints != nullptr)
                 {
                     OGRLinearRing *poRing =
                         OGRGeoJSONReadLinearRing(poObjPoints);
@@ -2983,6 +2978,10 @@ OGRPolygon *OGRGeoJSONReadPolygon(json_object *poObj, bool bRaw)
                 }
             }
         }
+        else
+        {
+            poPolygon = new OGRPolygon();
+        }
     }
 
     return poPolygon;