Unset vs Undefined

ownedbycats · 03-06-2021, 05:20 PM

For a column icon rule/saved search, is there any way to differentiate between an integer column value that has been deliberately set as "undefined" from one that has not been set at all?

I want to show an icon/make a search for books missing a value in #chaptercount, but a lot of books don't really have traditional chapters.

I thought about just putting '0' in for those books, but that would appear in the book details and break the math if I want to divide pagecount by chaptercount or something.

chaley · 03-06-2021, 06:02 PM

Yes, with a GPM template. The following example shows you how to do the test. Up to you to figure out what you want to do in each case.

Code:

program: 
	x = raw_field('#myint');
	if x == 'None' then
		'Not Set'
	else
		strcat('Is Set to ', x)
	fi

In the latest calibre release, raw_field() takes an optional second parameter specifying what to return if the field isn't defined. Example:

Code:

	x = raw_field('#myint', -999);

Regarding searching, you can distinguish between the two by looking for 'true' or 'false' as in

Code:

#myint:true

chaley · 03-07-2021, 06:23 AM

Actually, for rules you don't need the GPM template. You can instead use a double condition, one checking that the value is set and the other checking the actual value.

03-06-2021, 05:20 PM	#1
ownedbycats Custom User Title Posts: 10,829 Karma: 74203799 Join Date: Oct 2018 Location: Canada Device: Kobo Libra H2O, formerly Aura HD	Unset vs Undefined For a column icon rule/saved search, is there any way to differentiate between an integer column value that has been deliberately set as "undefined" from one that has not been set at all? I want to show an icon/make a search for books missing a value in #chaptercount, but a lot of books don't really have traditional chapters. I thought about just putting '0' in for those books, but that would appear in the book details and break the math if I want to divide pagecount by chaptercount or something. Last edited by ownedbycats; 03-06-2021 at 05:49 PM.

03-06-2021, 06:02 PM	#2
chaley Grand Sorcerer Posts: 12,375 Karma: 8012652 Join Date: Jan 2010 Location: Notts, England Device: Kobo Libra 2	Yes, with a GPM template. The following example shows you how to do the test. Up to you to figure out what you want to do in each case. Code: program: x = raw_field('#myint'); if x == 'None' then 'Not Set' else strcat('Is Set to ', x) fi In the latest calibre release, raw_field() takes an optional second parameter specifying what to return if the field isn't defined. Example: Code: x = raw_field('#myint', -999); Regarding searching, you can distinguish between the two by looking for 'true' or 'false' as in Code: #myint:true Last edited by chaley; 03-06-2021 at 06:04 PM.

03-07-2021, 06:23 AM	#3
chaley Grand Sorcerer Posts: 12,375 Karma: 8012652 Join Date: Jan 2010 Location: Notts, England Device: Kobo Libra 2	Actually, for rules you don't need the GPM template. You can instead use a double condition, one checking that the value is set and the other checking the actual value. Attached Thumbnails

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Sorting and undefined values	ownedbycats	Library Management	3	07-22-2020 01:32 PM
Removal of undefined classes from text	mcdummy	Editor	16	07-08-2020 07:45 AM
Is there way to list undefined classes?	phossler	Editor	10	07-29-2018 09:33 PM
W3C Validation says: Elements are undefined	verydeepwater	ePub	7	01-11-2013 05:09 AM
PRS-600 Sony library - Error undefined	omk3	Sony Reader	13	01-22-2010 10:52 AM

Advert