fix bug

diff --git a/lib/php/db.php b/lib/php/db.php
index cde8f1ce9b102f0d564a782c25bf361aab08f3ea..51c37256ea7ab6026dce5575d7f1018aae2a8995 100644 (file)
--- a/lib/php/db.php
+++ b/lib/php/db.php
@@ -1251,7 +1251,7 @@ class Db extends nb {
     return $row;
   }
 
-  public static function content_type2format($content_type) {
+  public static function content_type2format($content_type=null) {
     if (empty($content_type)) $content_type = self::client_content_type();
     switch (self::mime2ext($content_type)) {
       case "html":