Calibre move to new computer problem

[kpetzing]

I had several different libraries saved on my old computer's Calibre. I copied them to my new computer and all but one pulled in fine. The last one has a json file in the directory but no db file. So when I try to pull in those files I get an error. Is there any way to restore this? This was my main folder and had my personal ratings for many books and a couple added fields (tracking whether I read it, wanted to read, etc), so I'm really hoping theres some way to save it.

Thanks

[Adoby]

You need to find that db-file! If it is missing it might mean that the library isn't complete. Files missing...

However, if there are updated OPF-files along with the books, then the information is there as well. The OPF-files are a backup of the metadata that is stored in the database. So you could try to add the books to a new library, from the old. Make sure the new library has the same fields as your old library had.

You could try with one author, and see how it goes?

You would want to check in settings that metadata is read from the contents of the files, and not from the filenames.

[eschwartz]

drop in a random db, so you can open in that folder, then a database restore from Library Management. It will completely reload the database from the metatata in the OPF backups, and the library settings from the metadata_db_prefs_backup.json

[Adoby]

Originally Posted by eschwartz

drop in a random db, so you can open in that folder, then a database restore from Library Management. It will completely reload the database from the metatata in the OPF backups, and the library settings from the metadata_db_prefs_backup.json

Wouldn't that cause metadata in previous custom columns to disappear, if the random db doesn’t have the exact same custom columns as what was stored in the opf-files?

It could be a good idea to test it, but make sure to have a backup of the corrupt library, if it seems that a complete restore of all metadata fails.

It assume it should be possible to examine a opf-file to find out what custom columns was used when the opf-file was created?

[eschwartz]

Originally Posted by Adoby

Wouldn't that cause metadata in previous custom columns to disappear, if the random db doesn’t have the exact same custom columns as what was stored in the opf-files?

It could be a good idea to test it, but make sure to have a backup of the corrupt library, if it seems that a complete restore of all metadata fails.

It assume it should be possible to examine a opf-file to find out what custom columns was used when the opf-file was created?

Excellent point about the backup. I think it should be all right -- the db "should" only update the backup json and opf's if changes are performed. But better safe than sorry.

By definition, the restore database function is supposed to completely trash the db and restore all info whatsoever from the backups. book metadata is stored in the opf, and the metadata_db_prefs_backup.json contains ALL other data saved in the db -- it is supposed to ensure that by combining the json with the opf's, all the data is saved by which the db can be restored literally from nonexistence. As is indeed the case here.

TL;DR The custom columns are created from metadata_db_prefs_backup.json, and given values, if available (and they had better be), from the opf.