Unexpected child block disconection when changing a field option

[gpfernandezflorio]

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Description

When changing the field WHERE of the block text_charAt the child block in the input AT gets disconnected.


This only happends with text_charAt but it doesn't happen with text_getSubstring, lists_getIndex and lists_getSublist.

Reproduction Steps

1. Create a text_charAt block
2. Fill it's input AT
3. Change the field WHERE to "letter # from end"

Stack Trace

No response

Screenshots

No response

Browsers

Chrome desktop

[cpcallen]

Confirmed in develop.

Yes, this indeed seems like a bug! I suspect the problem is that some of the items in the dropdown remove the input completely, and this is probably being done when switching between "letter #" and "letter # from end" even though it appears not to be necessary in that particular case.

[gpfernandezflorio]

I saw that and suspected the same but the fact that it doesn't happen with the other blocks (text_getSubstring, lists_getIndex and lists_getSublist) makes me doubt.

Changing the function so the input is only removed when it is not necessary does indeed fix the problem. The question is why the other blocks don't need that. I couldn't find what else is different and also, I don't understand how the child block is maintained after a change (in the code I only see the input being removed and then added again but nothing about the child block being reconnected to the new input).

[gonfunko]

This no longer repros and may have been fixed by #8575.