From b36c5e762497812e8f15bb127cd5935d8ae42369 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 4 Feb 2022 08:19:18 +0530
Subject: [PATCH] When reviewing metadata if the newly downloaded metadata has
 no language but there is an existing language, ensure it is preserved. Fixes
 #1959981 [book metadata download fails language
 attribute](https://bugs.launchpad.net/calibre/+bug/1959981)

---
 src/calibre/gui2/metadata/diff.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/calibre/gui2/metadata/diff.py b/src/calibre/gui2/metadata/diff.py
index f368b992c9..2dfc7d5846 100644
--- a/src/calibre/gui2/metadata/diff.py
+++ b/src/calibre/gui2/metadata/diff.py
@@ -547,6 +547,13 @@ class CompareSingle(QWidget):
             if val != self.initial_vals[field]:
                 widgets.new.to_mi(self.current_mi)
                 changed = True
+        if changed and not self.current_mi.languages:
+            # this is needed because blank language setting
+            # causes current UI language to be set
+            widgets = self.widgets['languages']
+            neww, oldw = widgets[:2]
+            if oldw.current_val:
+                self.current_mi.languages = oldw.current_val
         return changed