Does app.use_controllers() support DI for controller constructors in v2.0.7?

[guillaume130679]

Hey all...just trying to confirm something about DI and controller registration in BlackSheep.

I'm on version 2.0.7 and running into issues with controllers that have constructor dependencies (e.g., services injected via init). I was expecting that calling app.use_controllers() would use the DI container (app.services) to resolve those dependencies, but what I’m seeing is that it tries to instantiate the controller with no args, leading to NoneType errors.

I tried passing services=app.services to app.use_controllers() and also to app.controllers_router.use_controllers(), but that throws a TypeError, so it seems unsupported in this version?

Is this expected behavior in 2.0.7? Was DI-based controller construction added in a later version? Just want to make sure I’m not missing something obvious before I either refactor the controllers or move to manual registration.

Thanks in advance!

[RobertoPrevato]

Hi,
Yes, DI is supported in Controllers since the very first implementation of controllers, as documented here. You don't need to call use_controllers() because it is called automatically when the application starts, you only need to register types as they should be resolved when configuring the application before start-up.

But controllers inheritance is supported only since version 2.3.0, I recommend upgrading to this. :)

Example:

from blacksheep import Application
from blacksheep.server.controllers import Controller, get


class ExampleDependencyForConstructor:
    pass


class ExampleDependencyForRequestHandler:
    pass


class HomeController(Controller):

    class_dep: ExampleDependencyForConstructor

    @get("/")
    def home(self, handler_dep: ExampleDependencyForRequestHandler):
        assert isinstance(self.class_dep, ExampleDependencyForConstructor)
        assert isinstance(handler_dep, ExampleDependencyForRequestHandler)
        return self.text(f"Hello World! {id(self.class_dep)} {id(handler_dep)}")


app = Application()

# Register types
app.services.register(ExampleDependencyForConstructor)
app.services.register(ExampleDependencyForRequestHandler)

curl http://127.0.0.1:44777/
Hello World! 140631871126144 140631871126448

If something is not working for you, please provide an example of your code.