Problem with template in Kobo Driver

[Terisa de morgan]

I've got this template for subtitle in the Kobo Driver, and it has been working till now (it works indeed when I send the books):

program:
	pags = field ("#pag");
	subDes = field ("#subd_enc");
	miVal = field ("#mi_val");
     mediaStar = field ("#media_s");
	
	subTitle = pags ;
	if (subDes)
	then
		subTitle = subTitle & "-" & subDes
	fi;

	if (miVal > 0)
	then
		subTitle = subTitle & " (" & rating_to_stars(miVal, 0);
		if (fractional_part (miVal) !=# 0)
		then
			subTitle = subTitle & "½" & ")"
		else
			subTitle = subTitle & ")"
		fi
	fi;
	subTitle

Now, just out of the blue, I try to modify another configuration in the driver and I get this message:

Spoiler:

calibre, version 8.5.0
ERROR: Invalid template for Subtitle: <p>The template "program:
pags = field ("#pag");
subDes = field ("#subd_enc");
miVal = field ("#mi_val");
mediaStar = field ("#media_s");

subTitle = pags ;
if (subDes)
then
subTitle = subTitle & "-" & subDes
fi;

if (miVal > 0)
then
subTitle = subTitle & " (" & rating_to_stars(miVal, 0);
if (fractional_part (miVal) !=# 0)
then
subTitle = subTitle & "½" & ")"
else
subTitle = subTitle & ")"
fi
fi;
subTitle" is invalid:<br>The rating must be a number between 0 and 5

What has changed? As I haven't touched it since the Kobo Extended driver was deprecated.
Additional info: I see the json file has as date: Jun 5, 2025, that I added another collection to ignore, and the change was fine. I've been up to date with 8 version, so I would be running the latest release at that moment. And, furthermore, it has just worked when I've sent books to the device.

[chaley]

What changed is that from 11 May the kobo driver now checks templates. Unfortunately it doesn't have a real book so it uses "fake" metadata. This can cause the problem you are seeing.

I think I will take out the validations. They seem to cause more problems than help.

[chaley]

I've submitted a fix to Kovid.

The specific problem is that the fake metadata for your rating column is text, which can't convert to a number. You can work around the problem until my fix is released by changing

miVal = field ("#mi_val");

to

miVal = format_number($#mi_val, 'd');

The format_number() function changes invalid text to the empty string, which is interpreted as 0 in a numeric context.