Make plpython's spi_execute interface handle NULLs properly.

From Andrew Bosma.

src/pl/plpython/plpython.c

@@ -29,7 +29,7 @@
  * MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  *
  * IDENTIFICATION
- *	$Header: /cvsroot/pgsql/src/pl/plpython/plpython.c,v 1.28 2003/01/31 22:25:13 tgl Exp $
+ *	$Header: /cvsroot/pgsql/src/pl/plpython/plpython.c,v 1.29 2003/01/31 22:35:24 tgl Exp $
  *
  *********************************************************************
  */
@@ -2181,6 +2181,7 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, int limit)
 	int			i,
 				rv;
 	PLyPlanObject *plan;
+	char *nulls;
 
 	enter();
 
@@ -2242,6 +2243,8 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, int limit)
 
 	if (nargs)
 	{
+		nulls = palloc((nargs + 1) * sizeof(char));
+
 		for (i = 0; i < nargs; i++)
 		{
 			PyObject   *elem,
@@ -2249,6 +2252,8 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, int limit)
 			char	   *sv;
 
 			elem = PySequence_GetItem(list, i);
+			if (elem != Py_None)
+			{
 					so = PyObject_Str(elem);
 					sv = PyString_AsString(so);
 
@@ -2262,10 +2267,24 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, int limit)
 					
 					Py_DECREF(so);
 					Py_DECREF(elem);
+
+					nulls[i] = ' ';
 			}
+			else
+			{
+				Py_DECREF(elem);
+				plan->values[i] = (Datum) 0;
+				nulls[i] = 'n';
+			}
+		}
+		nulls[i] = '\0';
+	}
+	else
+	{
+		nulls = NULL;
 	}
 
-	rv = SPI_execp(plan->plan, plan->values, NULL, limit);
+	rv = SPI_execp(plan->plan, plan->values, nulls, limit);
 	RESTORE_EXC();
 
 	for (i = 0; i < nargs; i++)