Clicking on book on device gives error

[HarryT]

A strange problem with the latest version of Calibre.

My Onyx T68 is connected to Calibre via a wireless device connection and CC running on the device.

I selected the "Device" view in Calibre and saw some books that did not have a check mark in the "In Library" column, which is peculiar, given the fact that all the books on the T68 were loaded there from Calibre.

When I click on one of these books in the device view I get the following error:

calibre, version 1.47.0
ERROR: Unhandled exception: <b>TypeError</b>:sequence item 0: expected string, NoneType found

calibre 1.47  isfrozen: True is64bit: False
Windows-7-6.1.7601-SP1 Windows ('32bit', 'WindowsPE')
32bit process running on 64bit windows
('Windows', '7', '6.1.7601')
Python 2.7.5
Windows: ('7', '6.1.7601', 'SP1', 'Multiprocessor Free')
Traceback (most recent call last):
  File "site-packages\calibre\gui2\book_details.py", line 609, in show_data
  File "site-packages\calibre\gui2\book_details.py", line 335, in show_data
  File "site-packages\calibre\gui2\book_details.py", line 28, in render_html
  File "site-packages\calibre\gui2\book_details.py", line 103, in render_data
  File "site-packages\calibre\ebooks\metadata\book\render.py", line 169, in mi_to_html
  File "site-packages\calibre\ebooks\metadata\book\base.py", line 604, in format_field
  File "site-packages\calibre\ebooks\metadata\book\base.py", line 680, in format_field_extended
TypeError: sequence item 0: expected string, NoneType found

All other books appear to be fine - it's just these (that claim not to be in the library) that cause the problem.

Any idea what the cause might be?

Thanks!

[kovidgoyal]

That's a strange error, it indicates that the tags field in the cached metadata for those books has null values. I dont know how that could happen, perhaps the .metadata.calibre file on the device was corrupted? Although I find it hard to credit that the corruption would be that specific.

Is there any pattern to these books? Were they sent recently, of a particular type, anything else?

In any case, I have committed some code to sanitize the values before displaying them that should workaround it. You could also just resend the files, which should fix it.

[HarryT]

Hi Kovid,

Thanks for the reply.

Do you remember a few weeks ago I reported an intermittent crash after sending a lot of books over the wireless connection? I suspect that what I'm seeing now is the consequence of that, because I'm pretty sure that these are books I was sending while the crash occurred. Might it be that Calibre sent the books, but didn't have a chance to update the metadata on the device, perhaps?

[kovidgoyal]

A crash in the middle of the send could explain it.

[chaley]

@HarryT: when that happens, go to the same book in library view and change its metadata somehow. It might be sufficient to open the metadata (single) editor and press OK, but that might no longer work since Kovid added a bunch of checks to see if metadata was actually changed. What will work is to add a nonsense tag that you remove later.

Once you have edited the metadata, click on the arrow device view icon and choose "Update metadata on device". This will refresh the metadata for that book. Alternatively, wait for the next connect, at which point it will update automatically.

[HarryT]

Thanks, chaley. Appreciate the help, as always.