Default field value priority is not consistent with setting sources priority about pydantic-settings HOT 3 CLOSED

Thanks @PrieJos for reporting this.

This is the final collected values from sources by pydantic-settings

{'MYAPP_FOO': 'value-from-osenv', 'MYAPP_BAR': '2', 'foo': 'value-from-init', 'bar': 3}

It will be passed to pydantic for validation. As populate_by_name is enabled, pydantic picks the values that you mentioned. There is no strict rule to tell pydantic which value has to be picked when populate_by_name is enabled and values are provided for both field name and alias.

So, you can fix the problem by providing init values by alias name like:

settings = Settings(**{'MYAPP_FOO':"value-from-init", 'MYAPP_BAR':3})

from pydantic-settings.

Thanks @hramezani for the reply.

So then as far as I understood you, the behavior you described here...

This is the final collected values from sources by pydantic-settings

{'MYAPP_FOO': 'value-from-osenv', 'MYAPP_BAR': '2', 'foo': 'value-from-init', 'bar': 3}

It will be passed to pydantic for validation. As populate_by_name is enabled, pydantic picks the values that you mentioned. There is no strict rule to tell pydantic which value has to be picked when populate_by_name is enabled and values are provided for both field name and alias.

... is somehow not fully consistent with the excerpt of the documentation I pasted in the ticket whenever aliases are used. Or at least, it is not clear enough in my opinion. So maybe a side note on the documentation warning about this will help. 🙏🏻

On the other hand, this solution you provided I checked it already and as you mentioned is returning the expected output.

So, you can fix the problem by providing init values by alias name like:

settings = Settings(**{'MYAPP_FOO':"value-from-init", 'MYAPP_BAR':3})

However I opted to write my own PydanticBaseSettingsSource that replaces the out-of-the-box InitSettingsSource implementation which is basically doing your proposed solution behind the scene.

Thanks!

Cheers
Jose M. Prieto

from pydantic-settings.

@PrieJos probably the documentation can be more clear about this. You can make a PR and improve it if you want and we appreciate it.
BTW, I am closing the issue for now.

from pydantic-settings.