Error in Book Details

[Tanjamuse]

Hi.

I tried moving my columns around in Book details, and when I went to Apply, I got the following error:

calibre, version 2.25.0
ERROR: Unhandled exception: <b>TypeError</b>:sequence item 0: expected string or Unicode, NoneType found

calibre 2.25 isfrozen: True is64bit: False
Windows-7-6.1.7601-SP1 Windows ('32bit', 'WindowsPE')
32bit process running on 64bit windows
('Windows', '7', '6.1.7601')
Python 2.7.9
Windows: ('7', '6.1.7601', 'SP1', 'Multiprocessor Free')
Successfully initialized third party plugins: Generate Cover && Manage Series && Wiki Reader && FanFicFare && EpubMerge && Quality Check && Read MP3 AudioBook metadata && User Category && Reading List && Modify ePub && Find Duplicates
Traceback (most recent call last):
File "site-packages\calibre\gui2\preferences\main.py", line 393, in accept
File "site-packages\calibre\gui2\preferences\main.py", line 354, in commit
File "site-packages\calibre\gui2\preferences\look_feel.py", line 461, in commit
File "site-packages\calibre\gui2\preferences\coloring.py", line 1039, in commit
File "site-packages\calibre\gui2\preferences\coloring.py", line 744, in commit
File "site-packages\calibre\library\coloring.py", line 60, in template
TypeError: sequence item 0: expected string or Unicode, NoneType found

Can anyone help?

[chaley]

You are in the same situation we discussed some time back. You have changed the type of a custom column by deleting it then re-adding it with the same name. That custom column has icon or coloring rules that are no longer valid.

[Tanjamuse]

Thank you.

[BetterRed]

@chaley - how about an option (--rules) be added to the calibredb custom_columns command to list columns used as colour/icon target, or a within a colour/icon rule?

BR

[chaley]

Originally Posted by BetterRed

@chaley - how about an option (--rules) be added to the calibredb custom_columns command to list columns used as colour/icon target, or a within a colour/icon rule?

BR

Such a thing is possible, albeit difficult because of advanced rules. However, I am not sure what problem it would solve. What you would get is a list of columns, not the contexts (rule/condition) in which they are evaluated. You can see this in an easier-to-view setting (again, ignoring advanced rules) in the various preferences screens. You can see the complete underlying template in metadata_db_prefs_backup.json. And unfortunately none of these solve Tanjamuse's problem: what rules were made invalid by the type change.

The problem arises when the column behind a lookup key changes type, something that can happen only when a column is deleted then a new column with a different type but with the same lookup key is added. In most cases, when this happens any rule with a condition making reference to that column must change because the semantics of the conditions change. Having the column names doesn't tell the user enough about that problem to find the offending conditions.

I have submitted a change to Kovid to show invalid conditions in the preferences rules display panels, making it easier to find rules that use columns that changed types. This along with a change Kovid made to prevent tossing exceptions when invalid rules are encountered should permit the user to find and fix problems without encountering calibre misbehavior.

[Tanjamuse]

I know it doesn't directly have anything to do with this, but would it be possible to create a "remove several" feature, instead of having to remove the icon rules one by one?

[theducks]

Originally Posted by chaley

You are in the same situation we discussed some time back. You have changed the type of a custom column by deleting it then re-adding it with the same name. That custom column has icon or coloring rules that are no longer valid.

I use Eudora 7. When I make a change to a 'mailbox' folder, it checks the Filter Rules and offers solution suggestions.
Delete is simple. The rule goes into
Rename: updates the rule or Delete

Since there is not an equivalent of 'Type', you could offer to Archive as TXT & Remove the rule. Letting the user later paste the old rule and fix the (type) errors.

[chaley]

@theducks: thanks for the suggestions. I spent some hours over the last few days looking at similar ideas, but ran into too many problems. One can delete and add custom columns using the CLI, where popping up random questions is not usually appreciated. In the GUI, columns aren't actually deleted until calibre exits, where we no longer have the option of asking the user any questions. There isn't anyplace one could "paste" an archived rule. Some conditions such as "is set" can survive a type change so deleting the rules halfway through the delete/add process can be suboptimal.. And so on.

Of course all of these problems could be fixed, but it is more work than I am willing to do for a problem that is so rare. I think the solution I submitted plus Kovid's change take us far enough.

[theducks]

Originally Posted by chaley

@theducks: There isn't anyplace one could "paste" an archived rule.

(I mostly use Column color rules and those were done a long time ago)

[chaley]

Originally Posted by Tanjamuse

I know it doesn't directly have anything to do with this, but would it be possible to create a "remove several" feature, instead of having to remove the icon rules one by one?

Kovid accepted the change. It is in source now and will be in the next calibre release.

[Tanjamuse]

Thanks

[BetterRed]

Originally Posted by chaley

I have submitted a change to Kovid to show invalid conditions in the preferences rules display panels, making it easier to find rules that use columns that changed types. This along with a change Kovid made to prevent tossing exceptions when invalid rules are encountered should permit the user to find and fix problems without encountering calibre misbehavior.

@chaley -

I anticipated adding a --rules option to calibredb custom_columns would be non-trivial. But I always ask these things, to not ask would be underestimate the ingenuity of yourself and Kovid

BR