`TypeError` coming through my custom add-on

Add-ons
1

Hey, I created an addon for my own work and it is not published on anki’s website. The objective of the addon is to populate a field at the time of the answer with text from a different card.

Source code of the add-on: Link

The add-on works through the CID_Index field in cards, if the CID_Index field exists and it is not empty, the add-on will to find the card and populate another field called Index in the card.

The Index field is added to the cards in the following manner:

<div class="index_data">{{edit:Index:}}</div>
<script>
		txt = document.querySelector(".index_data").textContent;
		if (txt == "") {
			document.querySelector(".index_data").innerHTML = "No Index";
		}
</script>

The add-on works fine with cards that have a CID_Index but in other instances it throws the following error:

Error
An error occurred. Please start Anki while holding down the shift key, which will temporarily disable the add-ons you have installed.
If the issue only occurs when add-ons are enabled, please use the Tools > Add-ons menu item to disable some add-ons and restart Anki, repeating until you discover the add-on that is causing the problem.
When you've discovered the add-on that is causing the problem, please report the issue to the add-on author.
Debug info:
Anki 2.1.65 (aa9a734f) Python 3.9.15 Qt 6.4.3 PyQt 6.4.0
Platform: Windows-10-10.0.22621
Flags: frz=True ao=True sv=3
Add-ons, last update check: 2023-07-09 13:18:28

Caught exception:
Traceback (most recent call last):
  File "aqt.webview", line 46, in cmd
  File "aqt.webview", line 153, in _onCmd
  File "aqt.webview", line 662, in _onBridgeCmd
  File "aqt.overview", line 92, in _linkHandler
  File "aqt.main", line 712, in moveToState
  File "aqt.main", line 733, in _reviewState
  File "aqt.reviewer", line 161, in show
  File "aqt.reviewer", line 181, in refresh_if_needed
  File "aqt.reviewer", line 243, in nextCard
  File "aqt.reviewer", line 361, in _showQuestion
  File "anki.cards", line 129, in question
  File "anki.cards", line 145, in render_output
  File "anki.template", line 235, in render
  File "anki.template", line 339, in apply_custom_filters
TypeError: can only concatenate str (not "NoneType") to str

Can someone please help me debug this? I tried multiple thing but couldn’t understand why this is happening.

Thanks in advance!

2

Regarding the error, your webview seems okay. Try printing some values and hunting down where the not

is.

3

Thank you so much for the response, FileX.

I added if name is not None and value is not None right after the loop to ensure that they are not None but it didn’t help :frowning:

What values are you referring to? I tried print name and value from the loop to check if everything was fine.

Looking at field: Index
Looking at field with value:
Looking at field: Note
Looking at field with value:
Looking at field: CID_Index
Looking at field with value:
Looking at field: Mnemonics
Looking at field with value:
Looking at field: Extra
Looking at field with value:
Looking at field: Syllabus
Looking at field with value:
Looking at field: Source
Looking at field with value:
Looking at field: Cloze99
Looking at field with value:
Caught exception:
Traceback (most recent call last):
  File "aqt.main", line 274, in on_focus_changed
  File "_aqt.hooks", line 3236, in __call__
  File "aqt.main", line 802, in on_focus_did_change
  File "aqt.reviewer", line 181, in refresh_if_needed
  File "aqt.reviewer", line 243, in nextCard
  File "aqt.reviewer", line 361, in _showQuestion
  File "anki.cards", line 129, in question
  File "anki.cards", line 145, in render_output
  File "anki.template", line 235, in render
  File "anki.template", line 339, in apply_custom_filters
TypeError: can only concatenate str (not "NoneType") to str

It looked like it looped through all the fields but later it gave an error in the end.

4

I think I found something interesting.

I added a print item in the filter_name at the start of the function

if not filter_name == "Index":
        print("Field: " + str(filter_name))
        return field_text

From the logs:

Field: edit
Caught exception:
Traceback (most recent call last):
  File "aqt.main", line 274, in on_focus_changed
  File "_aqt.hooks", line 3236, in __call__
  File "aqt.main", line 802, in on_focus_did_change
  File "aqt.reviewer", line 181, in refresh_if_needed
  File "aqt.reviewer", line 243, in nextCard
  File "aqt.reviewer", line 361, in _showQuestion
  File "anki.cards", line 129, in question
  File "anki.cards", line 145, in render_output
  File "anki.template", line 235, in render
  File "anki.template", line 339, in apply_custom_filters
TypeError: can only concatenate str (not "NoneType") to str

It looks like that this error is arising from a field called edit in this case but I do not have an edit field in the card. Probably this is causing the issue.

Does anyone know why this could be happening?

PS: I took my inspiration from this demo: https://github.com/ankitects/anki-addons/blob/main/demos/field_filter/__init__.py

5

Update: Checking the field_text None fixes the issue but it seems hacky. Probably there is a better way to fix this.

if not filter_name == "Index":
        if field_text is None:
              return ""
        return field_text
6

If you don’t have any further problems then that’s your solution. I guess it was a cause of returning None and the returned-value-handler which caused the error.

7

Yeah, it was returning None.
I will stick to my current solution for the time being until I come across something else that fixes this.