Fix mixed srid error on empty geometry with ST_Extent about #1400

docs/CHANGELOG.md

@@ -5,3 +5,4 @@
 - Add ST_OverpassDownloader function
 - Fix bug when read GeometryCollection with the ST_GeomFromGeoJSON function 
 - Fix github actions
+- Fix mixed srid error on empty geometry with ST_Extent #1400

h2gis-functions/src/main/java/org/h2gis/functions/spatial/properties/ST_Extent.java

@@ -61,15 +61,16 @@ public int getInternalType(int[] inputTypes) throws SQLException {
     @Override
     public void add(Object o) throws SQLException {
         if (o instanceof Geometry) {
-            Geometry geom = (Geometry) o;            
-            int currentSRID = geom.isEmpty()?0:geom.getSRID();
-            if(srid==0){
-                srid=currentSRID;
+            Geometry geom = (Geometry) o;
+            if(!geom.isEmpty()) {
+                int currentSRID = geom.getSRID();
+                if (srid == 0) {
+                    srid = currentSRID;
+                } else if (srid != currentSRID) {
+                    throw new SQLException("Operation on mixed SRID geometries not supported");
+                }
+                aggregatedEnvelope.expandToInclude(geom.getEnvelopeInternal());
             }
-            else if(srid!=currentSRID){
-                throw new SQLException("Operation on mixed SRID geometries not supported");
-            }
-            aggregatedEnvelope.expandToInclude(geom.getEnvelopeInternal());
         }
     }
 

h2gis-functions/src/test/java/org/h2gis/functions/spatial/SpatialFunctionTest.java

@@ -295,6 +295,28 @@ public void test_NULL_ST_Extent() throws Exception {
         st.execute("drop table ptClouds");
     }
 
+    @Test
+    public void test_Empty_ST_Extent() throws Exception {
+        st.execute("drop table if exists ptClouds");
+        st.execute("create table ptClouds(id INTEGER PRIMARY KEY AUTO_INCREMENT, the_geom GEOMETRY(MultiPoint));"
+                + "insert into ptClouds(the_geom) VALUES (ST_MPointFromText('MULTIPOINT(5 5, 1 2, 3 4, 99 3)',2154)),"
+                + "(ST_MPointFromText('MULTIPOINT(-5 12, 11 22, 34 41, 65 124)',2154)),"
+                + "(ST_MPointFromText('MULTIPOINT EMPTY',2154)),"
+                + "(ST_MPointFromText('MULTIPOINT(1 12, 5 -21, 9 41, 32 124)',2154));");
+        ResultSet rs = st.executeQuery("select ST_Extent(the_geom) tableEnv from ptClouds;");
+        assertTrue(rs.next());
+        Object resultObj = rs.getObject("tableEnv");
+        assertTrue(resultObj instanceof Geometry);
+        Envelope result = ((Geometry) resultObj).getEnvelopeInternal();
+        Envelope expected = new Envelope(-5, 99, -21, 124);
+        assertEquals(expected.getMinX(), result.getMinX(), 1e-12);
+        assertEquals(expected.getMaxX(), result.getMaxX(), 1e-12);
+        assertEquals(expected.getMinY(), result.getMinY(), 1e-12);
+        assertEquals(expected.getMaxY(), result.getMaxY(), 1e-12);
+        assertFalse(rs.next());
+        st.execute("drop table ptClouds");
+    }
+
     @Test
     public void test_TableEnvelope() throws Exception {
         st.execute("drop table if exists ptClouds");