Template error value:unknown field null

sfuller · 06-13-2011, 02:30 PM

I have a custom column that is broken in 8.5. The template is {tags:contains(fiction,AF,{null})}. I've had that column for a long time--has there been a syntax change?

chaley · 06-13-2011, 02:44 PM

No, no syntax changes, but yes, better error reporting.

There is a long-term bug that permits templates to be (sometimes) executed inside templates. You have been tripping over this bug, where {null} appears to be a template accessing the field named "null". There is no such field. I haven't fixed this bug because it could be considered a feature.

Another bug permitted use of bogus field names. That bug has been fixed, now reporting the error instead of doing something else. In your case, the 'something else' was probably returning the word "null". If that is what you want to happen, remove the {} around the word "null". If you want something else to happen, then change the template appropriately.

sfuller · 06-13-2011, 02:54 PM

I want the value to be AF or blank. I was using this from the manual as a guide--In a plugboard, you can set a field to empty (or whatever is equivalent to empty) by using the special template {null}. This template will always evaluate to an empty string.

sfuller · 06-13-2011, 02:59 PM

Fixed--I thought I needed a text if not match field from "contains(val, pattern, text if match, text if not match)". I just left the second parameter blank and the column is working.

chaley · 06-13-2011, 03:02 PM

Thanks for pointing out the error in the documentation. I have no clue why I wrote that back in September of last year. If {null} ever worked, then it was by accident. I will fix the doc.

Your solution is the correct one -- leave the parameter empty.

06-13-2011, 02:30 PM	#1
sfuller Member Posts: 17 Karma: 10 Join Date: Dec 2009 Device: kindle	Template error value:unknown field null I have a custom column that is broken in 8.5. The template is {tags:contains(fiction,AF,{null})}. I've had that column for a long time--has there been a syntax change?

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06-13-2011, 02:44 PM	#2
chaley Grand Sorcerer Posts: 11,733 Karma: 6690881 Join Date: Jan 2010 Location: Notts, England Device: Kobo Libra 2	No, no syntax changes, but yes, better error reporting. There is a long-term bug that permits templates to be (sometimes) executed inside templates. You have been tripping over this bug, where {null} appears to be a template accessing the field named "null". There is no such field. I haven't fixed this bug because it could be considered a feature. Another bug permitted use of bogus field names. That bug has been fixed, now reporting the error instead of doing something else. In your case, the 'something else' was probably returning the word "null". If that is what you want to happen, remove the {} around the word "null". If you want something else to happen, then change the template appropriately.

06-13-2011, 02:54 PM	#3
sfuller Member Posts: 17 Karma: 10 Join Date: Dec 2009 Device: kindle	I want the value to be AF or blank. I was using this from the manual as a guide--In a plugboard, you can set a field to empty (or whatever is equivalent to empty) by using the special template {null}. This template will always evaluate to an empty string.

06-13-2011, 02:59 PM	#4
sfuller Member Posts: 17 Karma: 10 Join Date: Dec 2009 Device: kindle	Fixed--I thought I needed a text if not match field from "contains(val, pattern, text if match, text if not match)". I just left the second parameter blank and the column is working.

06-13-2011, 03:02 PM	#5
chaley Grand Sorcerer Posts: 11,733 Karma: 6690881 Join Date: Jan 2010 Location: Notts, England Device: Kobo Libra 2	Thanks for pointing out the error in the documentation. I have no clue why I wrote that back in September of last year. If {null} ever worked, then it was by accident. I will fix the doc. Your solution is the correct one -- leave the parameter empty.

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