book metadata download fails language attribute

[Tillomar]

This is about calibre 5.34 on Win 10 21H2. Locale is German.

When downloading metadata for one ore more selected books, sometimes the language of the updated books is changed to "Deutsch". At first I attributed this to wrong metadata downloaded, but when I started to monitor the downloaded metadata before committing to the change, I noticed that the language attribute of the book to be modified were set to "Englisch", and the language attributes of the downloaded metadata was empty.

The following setup reproduces the bug most of the time:
(As my locale ist German, expect my translation of dialog names etc. not to be exact. If necessary, I should be able to reproduce this with an English locale also.)

* Select one or more books with language set to "Englisch".
(I don't know, and have not tried, if this works with other combinations of languages.)

* press Ctrl-D to invoke metadata download; select "metadata only" from dialog.

* from the "download completed" dialog, choose "check downloaded metadata".

* when promted with the side-by-side "check downloaded metadata (1 of 1)" dialog, check that the downloaded (left) language attribute is (or seems -- see comment down) empty, and the existing (right) language attribute ist set to "Englisch". If not, you MAY need to select a different book with different external metadata. Check also that the attribute name "languages" (on the left border) is not marked, signalling that no change to the attribute is expected.

* (If you would now just accept the new metadata as presented, the current language attribute should not be altered, and that will indeed happen in most cases. I have not detected the circumstances in which it does not, but those do definitly exist.)

* Now, instead of simply accepting the new metadata: merge the old ID metadata to the new ID metadata. Again, check that the attribute name "languages" is still not marked.

* press/click "ok".

In my setup, the language attribut of the book will be changed to "Deutsch". This happens book-by-book, that is, if you selected multiple books and downloaded metadata for them, and then go checking that metadata book by book, only those book will show the wrong language where you merged the ID metadata (again: mostly only those -- the bug also happens without checking the metadata first, but the curcumstances are unclear, and I just used the "merge ID metadata" to force the issue).

Additional comment: When you repeat the process for such a book, the next time the downloaded language metadata will in most cases not be empty, but show (correctly) "Englisch", while the current language in the DB will be "Deutsch" as set from the previous run.

The following metadata download sources are configured to run:
Amazon.com Multiple Countries (prio 5)
Google (prio 4)
Goodreads (prio 3)
Big Book Search (prio 1)
Fantastic Fiction (prio 1)
Open Library (prio 1)

The follwoing attributes are selected for download/update:
"Bewertung"
"Kommentare"
"Schlagwörter"
"Sprachen"
"Verlag"
"Veröffentlichungsdatum"

[Kovid Goyal (kovid)]

Fixed in branch master. The fix will be in the next release. calibre is usually released every alternate Friday.

 status fixreleased