Update the mysql driver to always return NULL columns, as this is needed for...

Update the mysql driver to always return NULL columns, as this is needed for the realtime API to work correctly.
(closes issue #16138)
 Reported by: sohosys
 Patches: 
       20091029__issue16138.diff.txt uploaded by tilghman (license 14)
 Tested by: sohosys


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@233050 65c4cc65-6c06-0410-ace0-fbb531ad65f3

addons/res_config_mysql.c

@@ -367,12 +367,13 @@ static struct ast_variable *realtime_mysql(const char *database, const char *tab
 
 		while ((row = mysql_fetch_row(result))) {
 			for (i = 0; i < numFields; i++) {
-				if (ast_strlen_zero(row[i]))
-					continue;
+				/* Encode NULL values separately from blank values, for the Realtime API */
+				if (row[i] == NULL) {
+					row[i] = "";
+				} else if (ast_strlen_zero(row[i])) {
+					row[i] = " ";
+				}
 				for (stringp = ast_strdupa(row[i]), chunk = strsep(&stringp, ";"); chunk; chunk = strsep(&stringp, ";")) {
-					if (!chunk || ast_strlen_zero(ast_strip(chunk))) {
-						continue;
-					}
 					if (prev) {
 						if ((prev->next = ast_variable_new(fields[i].name, chunk, ""))) {
 							prev = prev->next;