Pubdate in export title minus one

[Archibald Yates]

Hello!

I have a huge library of daily newspapers for Kindle in .mobi format. (Actually it is .pobi which I have simply renamed to .mobi to make them readable for Calibre.)

Now I want to convert them all to .ePub and to export them. After fiddling a bit with the export options the exported files look okay. But to my surprise the naming of the exported .ePub files is causing trouble:

I use the date format: %d.%m.%Y
And the file name should be: {title} (Kindle-Ausgabe) {pubdate}

"Kindle-Ausgabe" means "Kindle issue" in German, by the way.

But I don't get the publishing date that is displayed in the library's publishing date column but the publishing date minus one day when I export them. Having the proper publishing date is crucial for a daily newspaper, of course.

Is this a bug? Am I doing something wrong? Any help is appreciated!

[theducks]

this might be a time zone issue.
A difference on where it was published and your system

[Archibald Yates]

The newspapers were published in the same time zone. Unless it does matter that Amazon is located in the US.

But why could that be a problem at all? Do the e-books have timezone related timestamps or are their publish dates simple strings containing a date? It should be like that, because a newspaper published on July 10th in California is still a newspaper published on July 10th when read in Australia.

And the publish date is something set in the generating of the .pobi file, it is not the creation date of the file nor the download date. The former would be the day before the publish date and the latter would be sometimes later.

[Archibald Yates]

I have found this from quite a while ago.

So if it is actually a timezone problem, would it be possible to create a custom column with has pubdate + 1? And to use it in export instead of the original pubdate? And if so, how?

[kovidgoyal]

You can use the calibre template language for this:
https://manual.calibre-ebook.com/template_lang.html

[Archibald Yates]

Hello Kovid, thank you for your reply. And an even bigger thank you for the great software in general!

I have looked at the template language. But how could I provide a simple {pubdate+1} date in the name of the exported ePubs? I am not sure about the code I would have to use—date_arithmetic({pubdate}, 1d)?—and even more so where to put it.

And if it is all about the metadata's time stamp that includes the time zone why is Calibre handling this time stamp differently in the library window than in export?

[kovidgoyal]

Because in the library window it is shown in local timezone in export the UTC timezone is exported

[Archibald Yates]

Okay. But how do I get the proper (local) date into the file name? What are the specific steps?

[kovidgoyal]

change the template from {pubdate} to whatever you need using date_arithmetic

[Archibald Yates]

But where do I put date_arithmetic?

It does not work here:

[kovidgoyal]

{date_arithmetic(pubdate, whatever)}

[Archibald Yates]

Result:

PHP Code:

EXCEPTION: Wert: Unbekanntes Feld date_arithmetic(pubdate, 1d) 


"Wert" is value and "Unbekanntes Feld" is unknown field.

[chaley]

Look at the template language documentation for Single Function Mode, which is what you are trying to use. You will see that it requires the field to be operated, a colon, and the function to apply. As in:

{pubdate:date_arithmetic(1d)}

You might want to add the "format" argument the date_arithmetic() function. The format string is described in the date_format() function documentation.

[Archibald Yates]

Originally Posted by chaley

Look at the template language documentation for Single Function Mode, which is what you are trying to use. You will see that it requires the field to be operated, a colon, and the function to apply. As in:

{pubdate:date_arithmetic(1d)}

You might want to add the "format" argument the date_arithmetic() function. The format string is described in the date_format() function documentation.

That did help, thank you.

Luckily, I had tested the new export naming formula on both my newest and my oldest newspaper file with more than a decade between them. So I found out that, in order to maintain the suspense, Amazon seems to have used a different time zone, identical to mine, until some day in the early 2010s.

I am searching for the exact date of the switch because before that I will simply need {pubdate}. Sigh.