Truncate `InvalidCallbackReturnValue` size

[stdedos]

Would you consider truncating/ellipsisizing the {bad_val} output of

https://github.com/plotly/dash/blob/c729ef82e179623592d033929126f284837fd178/dash/_validate.py#L238C26-L253

?

Sometimes the output can be humongous, which affects browser rendering 😕

[alexcjohnson]

Great point! Feel like creating a PR? we should probably keep the existing behavior for reasonably-sized objects, but then past some size (1000 chars?) truncate and say something like ... (truncated - 1543464 characters total)

[stdedos]

Sure, why not? Anything can be done; but please give me your (repo's) requirements:

• How easy / complex you'd like the solution?
• Ellipsize / Truncate (with or without ...s?)
• ... at how many characters?
• ... with the text-prompt you included?

Maybe I can donate that even tomorrow.

[alexcjohnson]

Excellent, thank you in advance 😎

How easy / complex you'd like the solution?

As simple as possible while getting the job done. Particularly in error handling, short & readable code is more important to us than performance.

Ellipsize / Truncate (with or without ...s?)
... at how many characters?
... with the text-prompt you included?

Thinking about this more, since this error is always about a bad type we don't need that many characters, just enough to help you find the object in your code. So maybe 100 characters, then yes, ... plus a description like in my comment so it's clear to the reader what we did.

[stdedos]

The simplest one would've been {bad_val:.100s}, but not all classes implement __format__ 😅 (in my case, a @dataclass)
... neither would it have had the requested bells and whistles.

and {bad_val!s} does not support the format-language (so !.100s is invalid)

🙃

I have sent my review - I hope it is straightforward.