Calibre truncates long names on Win10 with long paths enabled.

[edojan]

Originally Posted by kovidgoyal

When sending to devices calibre always truncates to 256 as various devices have various limitations.

Sorry to bring this up again. I wonder if you can help to resolve The issue under windows 11 is as follows: if a book has a relatively long title in metadata (e.g. 70-75 characters) when it is added to Calibre library, the file name automatically generated by Calibre would be truncated to a random number of characters. Some file names would become 51 characters long, others - 55 characters, etc. When copied to devices (in my case Kobo Sage), the file names are not truncated at all (since they are less than 250 characters). Hence the files between the windows library and the device are named differently and have different hush numbers. This causes all kinds of problems when I am trying to synchronize of metadata generated by Koreader, etc. Since the same books are treated as different ones.
How can I have exactly the same file names between the main library in windows and file names copied to non-windows devices? E.g. if due to whatever limitation the book file in Calibre is 51 character long, then it would be transferred to connected devices without any changes. I would really appreciate your insight on how to resolve this.

[DNSB]

The file name sent to your ereader should be set from metadata depending on the template you use when saving. The name in the calibre library is not really relevant. Basically use the calibre library directory as a black box and stop peeking under it's skirts.

You may want to look at the location for your calibre library and move it to a location that has a shorter path. i.e. D:\Calibre\<library name>.

OTOH, out of perhaps morbid curiosity, what is a hush number? You may want to disable updating metadata in the file when it is being sent from calibre to your Sage since that can and will modify the file hash.

Depending on what file system you are using, other limitations may be present.

If you are trying to use very long file paths, have you set FileSystem LongPathsEnabled to enabled in the registry and does the application have set longPathAware true in the application's manifest?

[Quoth]

And with long paths Backups will fail. Actually backups and copies can fail even with regular paths if the names of directories or files are too long.

[edojan]

Thanks for your response. Please see below.

Originally Posted by DNSB

The file name sent to your ereader should be set from metadata depending on the template you use when saving. The name in the calibre library is not really relevant. Basically use the calibre library directory as a black box and stop peeking under it's skirts.

This is my understanding as well. The issue is that the same metadata produces different file names in Calibre library and the device irrespective of the template used.

You may want to look at the location for your calibre library and move it to a location that has a shorter path. i.e. D:\Calibre\<library name>.

Unfortunately, not feasible. The library is being synced to OneDrive and as such is located in C:/users/username/etc.

OTOH, out of perhaps morbid curiosity, what is a hush number?

You may want to disable updating metadata in the file when it is being sent from calibre to your Sage since that can and will modify the file hash. Depending on what file system you are using, other limitations may be present.

This was done earlier. Unfortunately, due to the file name differences the hashes are different even if when there is no change in the metadata

If you are trying to use very long file paths, have you set FileSystem LongPathsEnabled to enabled in the registry and does the application have set longPathAware true in the application's manifest?

FileSystem LongPathsEnabled was/is set to 1 (true), but I don't know how to change the application's manifest.
I wish there was a setting "keep device file names the same as in Calibre library" This would be ideal

[JSWolf]

Originally Posted by edojan

Thanks for your response. Please see below.



This is my understanding as well. The issue is that the same metadata produces different file names in Calibre library and the device irrespective of the template used.


Unfortunately, not feasible. The library is being synced to OneDrive and as such is located in C:/users/username/etc.




This was done earlier. Unfortunately, due to the file name differences the hashes are different even if when there is no change in the metadata


FileSystem LongPathsEnabled was/is set to 1 (true), but I don't know how to change the application's manifest.
I wish there was a setting "keep device file names the same as in Calibre library" This would be ideal

Turn off OneDrive. They way you have it set can cause all kinds of problems. And you NEVER EVER want tot two-way sync your library. Move your library so OneDrive will not touch it.

[chaley]

Originally Posted by edojan

This is my understanding as well. The issue is that the same metadata produces different file names in Calibre library and the device irrespective of the template used.

You have no control over calibre file names. There is no template you can set to control how calibre generates file names. Calibre can change a filename any time metadata changes.

On the other hand, you can use the format_paths() template function to get the current library file path for a book's formats and use that when sending to your device. Of course this won't help with long path names.

[edojan]

Originally Posted by chaley

You have no control over calibre file names. There is no template you can set to control how calibre generates file names. Calibre can change a filename any time metadata changes.

Understood. Changes in metadata are disabled. This is not an issue.

On the other hand, you can use the format_paths() template function to get the current library file path for a book's formats and use that when sending to your device. Of course this won't help with long path names.

I moved the library to a very short path:

C:\VAULTS\

This made no difference as Calibre keeps truncating the file names. E.g. the following book's name (as it appears in the metadata file) is

<dc:title>Исцеление духовных болезней</dc:title>

. Calibre adds this book to the library as

C:\VAULTS\CalibVault\Zhan-Klod Larshie\Istsielieniie dukhovnykh boliezniei (517)\Istsielieniie dukhovnykh boliez - Zhan-Klod Larshie.epub

The same book is transferred to the sage as:

E:\Zhan-Klod Larshie\Istsielieniie dukhovnykh boliezniei - Zhan-Klod Larshie.epub

The epub's file name is not the same. Calibre truncates it to

"Istsielieniie dukhovnykh boliez - Zhan-Klod Larshie.epub"

and on the device it appears as:

"Istsielieniie dukhovnykh boliezniei - Zhan-Klod Larshie.epub"

The difference is 4 characters. This screws up the file hash.

[edojan]

Originally Posted by JSWolf

Turn off OneDrive. They way you have it set can cause all kinds of problems. And you NEVER EVER want tot two-way sync your library. Move your library so OneDrive will not touch it.

I only kept it on OneDrive for backup purposes and always added books directly via Calibre (that is never directly via OneDrive). But just in case I just moved the libraries to a directory on C:\

[chaley]

As I said, calibre chooses how to name files using whatever algorithm is in the release when the file is created. The algorithm is complex, taking into consideration lengths of the title, authors, path to library, and library ID. You cannot turn off calibre's actions when metadata changes. Others have tried to reproduce calibre's naming with templates. To my knowledge, during 15 years none have been successful.

Your only chance is to use the calibre-generated name, available via format_paths(). Or

[edojan]

Originally Posted by chaley

Your only chance is to use the calibre-generated name, available via format_paths(). Or

Is there a way to use format_paths() to transfer the calibre-generated name to the devices? How? My current template to send to the device is {author}/{title} - {authors}

[chaley]

Originally Posted by edojan

Is there a way to use format_paths() to transfer the calibre-generated name to the devices? How? My current template to send to the device is {author}/{title} - {authors}

Use the template language documented in the calibre manual. https://manual.calibre-ebook.com/template_lang.html. in particular, General Program Mode.

[chaley]

The formats_path() function has problems if authors contain a comma. I need to fix this in base calibre.

In the meantime, this python template returns the basename of the book file

python:
def evaluate(book, context):
	import os
	from calibre.library import current_library_path

	fmt_metadata = book.get('format_metadata')
	if fmt_metadata:
		for v in fmt_metadata.values():
			# A calibre format name is roughly "author/title (id)/title - author.extension"
			# We want to return the last segment, stripping off the author and title 
			# directory names and the extension, leaving just the basename of the book file
			f = v['path']
			return f[f.rfind(os.sep)+1:f.rfind('.')] 
	else:
		raise ValueError('Book "{}" has no formats'.format(book.title))

[edojan]

Originally Posted by chaley

The formats_path() function has problems if authors contain a comma. I need to fix this in base calibre.

In the meantime, this python template returns the basename of the book file

python:
def evaluate(book, context):
	import os
	from calibre.library import current_library_path

	fmt_metadata = book.get('format_metadata')
	if fmt_metadata:
		for v in fmt_metadata.values():
			# A calibre format name is roughly "author/title (id)/title - author.extension"
			# We want to return the last segment, stripping off the author and title 
			# directory names and the extension, leaving just the basename of the book file
			f = v['path']
			return f[f.rfind(os.sep)+1:f.rfind('.')] 
	else:
		raise ValueError('Book "{}" has no formats'.format(book.title))

Thanks chaley for your assistance,
I really appreciate it. The problem is that I am not very technical. Would it be too much to ask for more detailed instructions? I have tried entering the code in the template editor, but it produces an error. What steps am I missing?

[edojan]

here is the screenshot

[chaley]

That error is harmless, caused by the template dialog not having a real book to work with. It will work when it us run "for real" -- when sending to the device.

This version removes the error.

python:
def evaluate(book, context):
	import os
	from calibre.library import current_library_path

	fmt_metadata = book.get('format_metadata')
	if fmt_metadata:
		for v in fmt_metadata.values():
			# A calibre format name is roughly "author/title (id)/title - author.extension"
			# We want to return the last segment, stripping off the author and title 
			# directory names and the extension, leaving just the basename of the book file
			f = v['path']
			return f[f.rfind(os.sep)+1:f.rfind('.')] 
	else:
		return 'title - author'