EPUB2 error while exporting

[csantanu]

Hi,

I am getting this error while using the Booktype installation which uses ebooklib as core package. Strangely, this is not happening with EPUB3 format and it is perfectly exporting.

When I am publishing using EPUB2 format, I am getting this error : KeyError : 'package_direction'.

File "/usr/local/lib/python2.7/dist-packages/celery/app/trace.py", line 375, $
R = retval = fun(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/celery/app/trace.py", line 632, $
return self.run(*args, **kwargs)
File "/usr/local/src/booktype/lib/booktype/apps/convert/tasks.py", line 50, i$
return func(request, *args, **kwargs)
File "/usr/local/src/booktype/lib/booktype/apps/convert/tasks.py", line 66, i$
result = run_conversion(*args, **kwargs)
File "/usr/local/src/booktype/lib/booktype/convert/runner.py", line 58, in ru$
conversion_result = converter.convert(book, output)
File "/usr/local/src/booktype/lib/booktype/convert/epub/converter.py", line 1$
epub_writer.write()
File "/usr/local/lib/python2.7/dist-packages/ebooklib/epub.py", line 1223, in$
self._write_opf_file()
File "/usr/local/lib/python2.7/dist-packages/ebooklib/epub.py", line 858, in $
if self.book.direction and self.options['package_direction']:
KeyError: 'package_direction'

Please help!
Thanks.
Santanu

[laudrain]

trying an advice: stop producing EPUB2 ;)
All what EPUB2 does is done better with EPUB3...

[csantanu]

Yes, I can take the EPUB3 route. But it produces a 'Guide' by default that is typically not required for most of the titles. How to switch off this feature? Booktype does not provide any interface for setting this up for EPUB3 format.

[aerkalov]

I haven't been working on the Booktype for couple of years so I wouldn't really know what have they changed but if you have your own installation you can always modify default options in file: /lib/booktype/convert/epub/writer.py

class Epub3Writer(ebooklib.epub.EpubWriter):
    DEFAULT_OPTIONS = {
        'epub2_guide': True,
        'epub3_landmark': True,
        'epub3_pages': True,
        'landmark_title': 'Guide',
        'pages_title': 'Pages',
        'spine_direction': True,
        'package_direction': False,
        'play_order': {
            'enabled': False,
            'start_from': 1
        }
    }

I just copy + pasted default options from ebooklib but modify it as you like. That will produce EPUB3 without guide.

[laudrain]

@csantanu I don't know Booktype. Thanks @aerkalov.

On guide element, latest EPUB 3.2 spec says:

The guide element [OPF2] is a legacy feature that previously provided machine-processable navigation to key structures in an EPUB Publication. It is replaced in EPUB 3 by landmarks in the EPUB Navigation Document.

[csantanu]

Thanks @aerkalov
I have solved the above mentioned bug as well. In the booktype writer implementation under the epub2 writer class this default option was set -
DEFAULT_OPTIONS = {
'epub2_guide': True,
'epub3_landmark': False,
'landmark_title': 'Guide'
}
This was throwing the error for package_direction key which was coming as null. After putting the entire default options chunk here, now epub2 export is working fine.