Q: Can Configuration values be made required?

[ms-lolo]

Couldn't find an example of this in the docs but I am trying to ensure that the system fails fast if the container hasn't been properly configured when the necessary provider is called. For example:

class MyContainer(DeclarativeContainer):

    config = Configuration()

    some_client = Singleton(SomeClient, config.something_important)

Right now, if I forget to set mycontainer.config.something_important before calling mycontainer.some_client(), then SomeClient will be given None as its parameter which is actually worse than forgetting to pass the argument at all because Python will allow it even if it's not an optional parameter. I don't want to sprinkle my classes with something_important is None checks.

What I really want is to be able to specify the exact keys I would expect in a Configuration provider and have the Container initialization fail if those values are not provided. Do you have any suggestions?

[ms-lolo]

I wonder if maybe what I want is a custom provider that behaves as a stricter version of Configuration.

[rmk135]

Hey @ms-lolo , that doesn't work out of the box, but that's a good idea. I'll think how it could be implemented. The wild guess I have now is to make something like this:

class MyContainer(DeclarativeContainer):

    config = Configuration()
    config.something_important.required()

    some_client = Singleton(SomeClient, config.something_important)

There also could be a strict mode for Configuration provider that will prohibit using any undefined values.

[rmk135]

I have released version 4.10.0 with strict mode and required modifier features for the Configuration provider. Here is a doc: https://python-dependency-injector.ets-labs.org/providers/configuration.html#strict-mode-and-required-options

[rmk135]

Closing the issue. Reopen if needed.

[rmk135]

@ms-lolo , thanks for suggesting the feature!

[ms-lolo]

this seems to solve my problem, thank a lot!

[rmk135]

Glad to hear that! Thank you again