Propagate configuration values on multiple containers

[dcendents]

Hi,

I'd like to use mutiple containers like in the example: https://python-dependency-injector.ets-labs.org/examples/application-multiple-containers.html

But I have the following problem, my factories use the first configuration value and ignore the new values.
If I use a single container it works fine.

Here is an example that re-create the problem:

from dependency_injector import containers, providers


class Core(containers.DeclarativeContainer):

    config = providers.Configuration()

    greetings = providers.Factory(str, config.greeting)


class Application(containers.DeclarativeContainer):

    config = providers.Configuration()

    core = providers.Container(
        Core,
        config=config,
    )

    greetings = providers.Factory(str, config.greeting)


if __name__ == '__main__':
    container = Core()

    container.config.set("greeting", "Hello World")
    assert container.greetings() == "Hello World"

    container.config.set("greeting", "Hello Bob")
    assert container.greetings() == "Hello Bob"

    container = Application()

    container.config.set("greeting", "Hello World")
    assert container.greetings() == "Hello World"
    assert container.core.greetings() == "Hello World"

    container.config.set("greeting", "Hello Bob")
    assert container.greetings() == "Hello Bob"
    # Last one will fail, value is still "Hello World"
    assert container.core.greetings() == "Hello Bob"

I'd appreciate if you could tell me why the first value set can be seen by the Core container but subsequent updates are ignored

Thanks

[rmk135]

Hi @dcendents ,

Cool finding. That's definitely a bug. Configuration provider has a cache. It uses cache to avoid traveling for the value to a root provider. In that case cache root provider does not reset cache for a child config provider in a child container.

The workaround is to manually call container.core.config.reset_cache(). I'll also publish a fix on PyPI. Thanks for reporting the issue.

[rmk135]

@dcendents I've published a fix in 4.31.0. Thanks again for reporting the issue.

[dcendents]

Thanks @rmk135 it was quick and indeed 4.31.0 fixes the problem.