[SEDONA-199] Update documentation for ST_NDims as it now supports M d…

…imension. (#768)

docs/api/flink/Function.md

@@ -536,7 +536,7 @@ FROM polygondf
 
 ## ST_NDims
 
-Introduction: Returns the coordinate dimension of the geometry. It supports 2 - (x,y) , 3 - (x,y,z). Currently the geometry serializer in sedona-sql does not support M dimension, 4D geometries with ZM coordinates will have their M coordinates dropped and became 3D geometries. We're working on a new geometry serializer to resolve this issue.
+Introduction: Returns the coordinate dimension of the geometry.
 
 Format: `ST_NDims(geom: geometry)`
 

docs/api/sql/Function.md

@@ -897,7 +897,7 @@ Result:
 ```
 ## ST_NDims
 
-Introduction: Returns the coordinate dimension of the geometry. It supports 2 - (x,y) , 3 - (x,y,z). Currently the geometry serializer in sedona-sql does not support M dimension, 4D geometries with ZM coordinates will have their M coordinates dropped and became 3D geometries. We're working on a new geometry serializer to resolve this issue.
+Introduction: Returns the coordinate dimension of the geometry.
 
 Format: `ST_NDims(geom: geometry)`
 

flink/src/test/java/org/apache/sedona/flink/FunctionTest.java

@@ -433,6 +433,15 @@ public void testNDims() {
         int result = (int) first(polygonTable).getField(0);
         assertEquals(3, result, 0);
     }
+
+    @Test
+    public void testNDimsForMCoordinate() {
+        Object result = first(tableEnv.sqlQuery("SELECT ST_NDims(ST_GeomFromWKT('POINT M (1 2 3)'))")).getField(0);
+        assertEquals(result, 3);
+        result = first(tableEnv.sqlQuery("SELECT ST_NDims(ST_GeomFromWKT('POINT ZM (1 2 3 4)'))")).getField(0);
+        assertEquals(result, 4);
+    }
+
     @Test
     public void testXMax() {
         Table polygonTable = createPolygonTable(1);

sql/src/test/scala/org/apache/sedona/sql/functionTestScala.scala

@@ -481,6 +481,16 @@ class functionTestScala extends TestBaseScala with Matchers with GeometrySample
       assert(test.take(1)(0).get(0).asInstanceOf[Int] == 3)
     }
 
+    it("Passed ST_NDims with XYM point") {
+      val test = sparkSession.sql("SELECT ST_NDims(ST_GeomFromWKT('POINT M(1 2 3)'))")
+      assert(test.take(1)(0).get(0).asInstanceOf[Int] == 3)
+    }
+
+    it("Passed ST_NDims with XYZM point") {
+      val test = sparkSession.sql("SELECT ST_NDims(ST_GeomFromWKT('POINT ZM(1 2 3 4)'))")
+      assert(test.take(1)(0).get(0).asInstanceOf[Int] == 4)
+    }
+
     it("Passed ST_GeometryType") {
       var test = sparkSession.sql("SELECT ST_GeometryType(ST_GeomFromText('LINESTRING(77.29 29.07,77.42 29.26,77.27 29.31,77.29 29.07)'))")
       assert(test.take(1)(0).get(0).asInstanceOf[String].toUpperCase() == "ST_LINESTRING")