OPDS Content Server to provide last modification date

[cedhax]

It seems that the OPDS Content Server of Calibre does not provide the modified date of each book in its generated XML files, while the HTML Content Server does provide it in its generated HTML files. Is there a way to fix this?

For the motivation for this request, please see this post, which is a reply from the developer of MapleRead to one of its users. Since I haven't seen a post by glenm125 on this issue yet, I'm doing it as another user who is also interested in the same question.

[kovidgoyal]

You want a last modified date for the individual e-book files or the overall book metadata? In which OPDS feed, the acquisition feed? In what format?

[cedhax]

As a user, I think a last modified date for an e-book file itself and a last modified date for its metadata are both useful. As for the specific XML syntax required, I'd rather leave it to you and sbaylor, the MapleRead developer, to whom I have just left a message there.

[mattcurtis]

Originally Posted by kovidgoyal

You want a last modified date for the individual e-book files or the overall book metadata? In which OPDS feed, the acquisition feed? In what format?

In the OPDS feed perhaps on a global basis, with a date element indicating last modified file date & last modified metadata date of any book. This would be useful for determining if anything had changed since the feed was last checked, and when it changed.

As for the Acquisition Feed, it would be great if each entry had the same as above, file date modified & metadata modified, with a bonus: file hashes! MD5 preferably. Would be incredibly useful for comparing files.

Bonus question: Exactly what does Calibre base the existing <updated /> elements for feed and entry on now?

[kovidgoyal]

It's a long time since I looked at OPDS (the JSON APIs are much better for integrating with the calibre server), however, IIRC <updated> is the last modified date of metadata.db i.e. the entire calibre library.

[kovidgoyal]

https://github.com/kovidgoyal/calibr...fc7e06cdbbe13a

[glenm125]

First, thanks for cedhax for posting this thread in response to my original comment elsewhere.

Originally Posted by kovidgoyal

You want a last modified date for the individual e-book files or the overall book metadata? In which OPDS feed, the acquisition feed? In what format?

I'm not expert in the OPDS format nor nomenclature, so let me instead describe from a user point of view what I want to achieve.

Part of what I read in Calibre and related readers is fanfiction. As authors extend those stories with new chapters, I use fanficfare to generate epubs from content of those sites into my calibre library. I presume this updates the metadata (file size, date, 'completed' tag, etc), perhaps also updating author (if author changed his name, not an uncommon thing!). As well of course as replacing the epubs.

Whether a new version or not has come, I might have also updated the metadata, eg with a rating or additional tags.

So it would seem to me that it would be useful to have latest updated date for metadata, and latest updated date for each file, assuming the OPDS format supports both. That provides most visibility into change in downstream tools.

This would allow a reader application to know when to merge metadata changes in, and whether to flag a book (otherwise thought to be read in the client) as now unread (because it has changed). And even show how much longer the book is compared to the read content (new content length less length when last read).

But again, I'm not expert in the formats or established usage paradigms of this content. Library and reader authors should probably comment on what would help them most.

Hope this helps,

glen

[sbaylor]

Originally Posted by kovidgoyal

https://github.com/kovidgoyal/calibr...fc7e06cdbbe13a

Thanks! The changes look great. The ball is in my court now.

[cedhax]

@kovidgoyal - The OPDS Content Server is broken in calibre 2.67 (latest version). On pressing "By Newest", or "By Title", etc., it returns the following error message.

500 Internal Server Error

The server encountered an unexpected condition which prevented it from fulfilling the request.
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Note that previous versions of calibre are ok.

[chaley]

Originally Posted by cedhax

@kovidgoyal - The OPDS Content Server is broken in calibre 2.67 (latest version). On pressing "By Newest", or "By Title", etc., it returns the following error message.

500 Internal Server Error

The server encountered an unexpected condition which prevented it from fulfilling the request.
-------------------------------------
Powered by CherryPy 3.2.2


Note that previous versions of calibre are ok.

See https://www.mobileread.com/forums/sho...d.php?t=278278