CP-40669: Restore database should not require ref as the first

attribute of row

When restore xapi database from xml file, xapi require ref be
the first attribute of row, This is not flexible, especially when
need to parse and save the xml files.

This commit fix this issue by search ref in the attribute list

Signed-off-by: Lin Liu <lin.liu@citrix.com>

ocaml/database/db_xml.ml

@@ -146,15 +146,24 @@ module From = struct
               f acc
           | (_, "table"), [((_, "name"), tblname)] ->
               f (tableset, Table.empty, tblname, manifest)
-          | (_, "row"), ((_, "ref"), rf) :: rest ->
-              (* Remove any other duplicate "ref"s which might have sneaked in there *)
-              let rest = List.filter (fun ((_, k), _) -> k <> "ref") rest in
+          | (_, "row"), rest ->
+              let ref_l, rest =
+                List.partition (fun ((_, k), _) -> k = "ref") rest
+              in
+
               let ctime_l, rest =
                 List.partition (fun ((_, k), _) -> k = "__ctime") rest
               in
               let mtime_l, rest =
                 List.partition (fun ((_, k), _) -> k = "__mtime") rest
               in
+              let rf =
+                match ref_l with
+                | (_, ref) :: tl ->
+                    ref (* Pick up the first ref and ignore others *)
+                | [] ->
+                    raise (Unmarshall_error "Row does not have ref atrribute")
+              in
               let ctime =
                 match ctime_l with
                 | [(_, ctime_s)] ->