Thread: Covers dissapearing
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Old 07-28-2019, 08:04 AM   #8
davidfor
Grand Sorcerer
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Posts: 24,905
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Join Date: Jul 2011
Location: Sydney, Australia
Device: Kobo:Touch,Glo, AuraH2O, GloHD,AuraONE, ClaraHD, Libra H2O; tolinoepos
Quote:
Originally Posted by JIPG-reader View Post
Well, finally I have solved the problem with the covers .

I expect it will survive after next syncs (I have done one, without losing the covers ...).

Basically, it seems that when a book (edition?) is not longer available in the kobo store, an update is done to the database (KoboReader.sqlite) during a sync, and the pointer to the cover is changed with and id that does not exist. Nevertheless, the image with the previous cover still exists with the old id within the folder .kobo-images.
All I can say is that this isn't an issue for me. While I haven't looked at every book that has stopped being sold by Kobo, I haven't noticed any missing covers. And for everyone I have looked at, the cover is there with no issues. I don't track the various ids, so I have no idea if they have changed over time.
Quote:
I have opened the database of an old backup which has not the problem and looking for the book title in the field "Title" (NOT in the field "BookTitle", this was my mistake), I identified the old cover id (in the field "ImageId") and copied it to the actual database ImageId field for the corresponding book (looking for the title again in the field Title, not BookTitle). By the way, check that the entry you are changing has a field contentType=6. Other entries of the same book has different numbers (e.g. 9 or 899).
Which is what I said in my post. I have a very good understanding of most of the database.
Quote:
Saving the changes, I have now the covers still "alive" after some power cycles

As always, if someone try this, first make a backup of the content of the memory or at least of the database KoboReader.sqlite.

And finally, thank you to davidfor for his hints to solve the problem.
That is very unlikely to survive a sync. I have fiddled with the data in the database for purchased books before and it is always "fixed" by a sync. I'm pretty sure that on the next sync, the cover ids will change again.

Three things you could try are:
  • Remove the book from the device, and download it again. This might force an update.
  • Remove the book from "My Books". This removes it from the device and puts it in the archive. Then restore the book and let it download again. This will force an update for the book.
  • Use "Repair account" that is on the Device info page of the settings. This will check and update as necessary everything for the books. If there are problems like you are seeing, it should fix them.

The covers are stored on akamai servers. If you want to fetch/check an individual cover, you can. The URL looks like:

Code:
http://kbimages1-a.akamaihd.net/a7511e44-7dd2-4334-a188-003611d34c07/353/569/80/False/cover.jpg
That is the imageId for the book. The next two numbers are the resolution. Those are the size used used the book details page. The full book size is the same as the screen resolution. The "80" appears to be a quality, "False" for colour or "True" for greyscale and the name doesn't matter. That is the for one of the books that I have that Kobo has since stopped selling. The covers show up fine on the device. And I did the second of the above checks to make sure they didn't disappear.
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