html to EPUB - added class into <html> tag

etihwmot · 08-04-2020, 05:57 PM

I'm converting a pretty clean .html file into EPUB using Calibre 4.20 and have run into a validation problem. The EPUB 'works' fine on my test reading apps/devices, but it does not validate due to:

class="calibre" being inserted into the <html> tag, with the resulting string in each chapter split file:

<html xmlns="http://www.w3.org/1999/xhtml" class="calibre">

Now, I can go in and edit the 30+ chapter files and remove the offending string, but I'd like to know how it got there in the first place!

Tom
interestingly, Amazon and Kobo didn't mind the EPUB, it was Apple that was fussy and forced me to validate the code.

hobnail · 08-04-2020, 07:13 PM

You could use the calibre editor and select all of the html / xhtml files and using a search and replace, replace

Code:

<html .* class="calibre">

with

Code:

<html xmlns="http://www.w3.org/1999/xhtml">

For converting html to epub I prefer to start with a new / blank epub and add an html / xhtml file for each chapter and select and copy each chapter in the html file (if they're in separate files then select what's between the body tags) and paste it between the body tags in each html / xhtml file in the epub. As you've discovered, converting can introduce problems.

jhowell · 08-04-2020, 07:17 PM

Quote:

Originally Posted by etihwmot

I don't see anything obviously wrong with that code. What is the validation error?

Quote:

Originally Posted by etihwmot

...I'd like to know how it got there in the first place!

Conversion by calibre reorganizes CSS styles and assigns class names that start with "calibre".

etihwmot · 08-04-2020, 07:28 PM

Quote:

Originally Posted by jhowell

I don't see anything obviously wrong with that code. What is the validation error?

CSS styles/attributes shouldn't be in the <html> tag. And there's none in my .html file before sticking it through Calibre. Here's the error:

Error while parsing file: attribute "class" not allowed here; expected attribute "dir", "lang", "version" or "xml:lang"

The error makes sense to me, but Calibre adding a styling attribute where there were none, does not.

hobnail · 08-04-2020, 07:31 PM

Quote:

Originally Posted by etihwmot

CSS styles/attributes shouldn't be in the <html> tag.

As jhowell said, that class on the html tag is valid. You don't often see that but it's ok. Try running it through an epub validator and it should pass. It's Apple that's making it a problem.

etihwmot · 08-04-2020, 07:32 PM

Quote:

Originally Posted by hobnail

You could use the calibre editor ....

Good point about using calibre's editor - I always work in a text editor, so hadn't thought of it.

I don't want to go down the route of not trusting the conversion. My files are super clean and light and calibre does exactly what I need with a coupla clicks.

hobnail · 08-04-2020, 07:37 PM

Here's the standard/official validator for Calibre that you can use:

https://www.mobileread.com/forums/sh...ight=validator

You should always check your epubs with that before you submit them to amazon, et. al.

etihwmot · 08-04-2020, 07:42 PM

Quote:

Originally Posted by hobnail

As jhowell said, that class on the html tag is valid. You don't often see that but it's ok. Try running it through an epub validator and it should pass. It's Apple that's making it a problem.

Your pre-edit was right - the html is valid. But your post edit is what I'd done to check Apple's error-finding. I stuck it through epub validator on ebookit's site, and it flagged the same issues.

But that doesn't mean it isn't Apple messing it up by being weird, and then the validator following suit. I'm used to having to add extra shizzle for Apple systems, and having Apple ignore stuff, but I've never had to remove something to get it to work.

etihwmot · 08-04-2020, 07:44 PM

Quote:

Originally Posted by hobnail

Here's the standard/official validator for Calibre that you can use:

https://www.mobileread.com/forums/sh...ight=validator

You should always check your epubs with that before you submit them to amazon, et. al.

I do not have java running on this machine, so can't run that plugin for now.

But thanks for the responses, you and jhowell have been useful!

hobnail · 08-04-2020, 07:47 PM

Quote:

Originally Posted by etihwmot

I do not have java running on this machine, so can't run that plugin for now.

But thanks for the responses, you and jhowell have been useful!

The installation instructions for java may sound a bit hairy but it's really no big deal. And that calibre plugin is using the validator that is the official one.

JSWolf · 08-04-2020, 08:41 PM

@etihwmot go into the Calibre editor and go to Edit > Preferences > Integration with Calibre and uncheck Update metadata embedded in the book when opening. This will prevent the editor from making any changes to your ePub when opening them in the editor and all changes will be done by you.

And you do not need to use a text editor after this change is made.

JSWolf · 08-04-2020, 08:43 PM

Quote:

Originally Posted by hobnail

Here's the standard/official validator for Calibre that you can use:

https://www.mobileread.com/forums/sh...ight=validator

You should always check your epubs with that before you submit them to amazon, et. al.

I use both the Calibre editor's validater and epubcheck and make sure both say there are no errors. I do sometimes let warnings go with the Calibre validater but that's my choice.

JSWolf · 08-04-2020, 08:44 PM

Quote:

Originally Posted by etihwmot

I do not have java running on this machine, so can't run that plugin for now.

But thanks for the responses, you and jhowell have been useful!

If you do install Java, go for the 64-bit version if you are running a 64-bit OS as there are less problems with the 64-bit Java.

kovidgoyal · 08-04-2020, 10:24 PM

calibre only inserts a class on html if there are some styles applied to html in the input document.

etihwmot · 08-05-2020, 11:30 AM

Quote:

Originally Posted by JSWolf

@etihwmot go into the Calibre editor and go to Edit > Preferences > Integration with Calibre and uncheck Update metadata embedded in the book when opening. This will prevent the editor from making any changes to your ePub when opening them in the editor and all changes will be done by you.

And you do not need to use a text editor after this change is made.

Thanks for the heads up on this!

08-04-2020, 05:57 PM	#1
etihwmot Junior Member Posts: 8 Karma: 10 Join Date: Aug 2020 Device: android	html to EPUB - added class into <html> tag I'm converting a pretty clean .html file into EPUB using Calibre 4.20 and have run into a validation problem. The EPUB 'works' fine on my test reading apps/devices, but it does not validate due to: class="calibre" being inserted into the <html> tag, with the resulting string in each chapter split file: <html xmlns="http://www.w3.org/1999/xhtml" class="calibre"> Now, I can go in and edit the 30+ chapter files and remove the offending string, but I'd like to know how it got there in the first place! Tom interestingly, Amazon and Kobo didn't mind the EPUB, it was Apple that was fussy and forced me to validate the code.

08-04-2020, 07:13 PM	#2
hobnail Running with scissors Posts: 1,553 Karma: 14325282 Join Date: Nov 2019 Device: none	You could use the calibre editor and select all of the html / xhtml files and using a search and replace, replace Code: <html .* class="calibre"> with Code: <html xmlns="http://www.w3.org/1999/xhtml"> For converting html to epub I prefer to start with a new / blank epub and add an html / xhtml file for each chapter and select and copy each chapter in the html file (if they're in separate files then select what's between the body tags) and paste it between the body tags in each html / xhtml file in the epub. As you've discovered, converting can introduce problems. Last edited by hobnail; 08-04-2020 at 07:21 PM.

08-04-2020, 07:37 PM	#7
hobnail Running with scissors Posts: 1,553 Karma: 14325282 Join Date: Nov 2019 Device: none	Here's the standard/official validator for Calibre that you can use: https://www.mobileread.com/forums/sh...ight=validator You should always check your epubs with that before you submit them to amazon, et. al. Last edited by hobnail; 08-04-2020 at 07:40 PM.

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