It looks like we have a solution to the problem of the user not being able to
restore a corrupt document from Versions Browser because the document is
corrupt, and so she can’t open it, and so she can’t File > Revert to > Browse
All Versions.
The solution is:
• Override -[NSDocument openDocumentWithContentsOfURL:display:error:].
• After invoking super, look in returned error for SQLite error code:11,
'database disk image is malformed’.
• If that error is found, clear all data from the document on the disk.
• In its place, copy in data from a good, empty document.
• Invoke super again. The document will open this time.
• Display a sheet informing user that document was corrupt and suggest File >
Revert to > Browse All Versions.
I’ve not written the code yet, just done the above manually with a Core Data
SQLite document that has legacy Delete/Rollback journaling. Corruption was
simulated by punching out the middle of the file with a hex editor. I also
used a hex editor to nuke and pave the document. Result: Versions Browser
showed previous versions of the corrupted document, as desired. After
restoring one, I was able to edit, save, close, and re-open it and nothing
complained.
Happily, no reverse engineering of /.DocumentRevisions-V100 was necessary, but
I’m still open to any better ideas. Did I miss an easier solution to this
problem that is built into Cocoa?
I’m aware that the magic in NS(Persistent)Document often comes back to bite
with a vengeance days or weeks later. I shall post again if I have any trouble.
___
Cocoa-dev mailing list (Cocoa-dev@lists.apple.com)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com
This email sent to arch...@mail-archive.com
