upgrade from pydantic v2.4.3 to v2.5.1 introduced a regression using `BaseSettings` with union-types about pydantic-settings HOT 5 CLOSED

I think it was a bug that was introduced and got fixed.
I don't have any idea probably @davidhewitt can help here.

Thanks for letting us know.

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Thanks @spex66 for reporting this.

Yeah, as you mentioned the fix is the change StepSingle and StepRange to inherit from BaseModel.

The reason for this problem is when you initialize the StepsAlternative, Pydantic initializes the StepSingle and StepRange. the error message comes from StepRange.

we had the same behavior in 2.4.2 (initializing all the models) but I don't know what exactly was the change in 2.5.

probably @davidhewitt can explain.

from pydantic-settings.

thx @hramezani for your quick feedback!

But I can confirm that I double checked today, switching versions back and forth, that this code was working.
So even if the behavior has not changed "behind the scenes", the error is new and smells like a regression.

from pydantic-settings.

hi @hramezani
I've retested using latest releases

• the reported error happened with pydantic 2.5.1, pydantic-core 2.14.3, pydantic-settings 2.1.0
• but the error does not happen using (latest) pydantic 2.5.2, pydantic-core 2.14.5, pydantic-settings 2.1.0

ofc I have no idea which change in pydantic or core has resolved it, maybe you have an idea?
So from my side the ticket can be closed

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@spex66 @hramezani I'm not aware of a particular bug that would have caused this and since been fixed.

I tried to repro with the versions listed here, I cannot repro with any of 2.5.0, 2.5.1, or 2.5.2. Strange.

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