referencing dependency method in one class?

[pincoin]

Hello,

I have another question about dependency functions.

The official documentation explains dependency functions and class constructors.

Is it possible to define them as methods of a class?

For example, suppose that I've got source code like this:

class MyDependencyClass:
    def sub_dependency(self):
        print("sub_dependency")
        return("sub_dependency")

    def dependency(self, dep=Depends(self.sub_dependency)):
        print("dependency")
        return("dependency")

I cannot write the code like this because self is not defined at self.sub_dependency.

Do I have to define all dependencies as functions?

Of course, it is not a FastAPI issue. It's rather Python grammar issue. However, I hope to get your opinion and help.

Thank you.

[pincoin]

Hi,

After I asked, I searched some articles, posts, and I found out it's impossible because Python does not support this grammar not like Javascript:

let getPrice = function( price, tax = price * taxRate() ) {
    return price + tax;
}

I decided to add my dependency method dynamically into an instance like this:

authentication = get_authentication_backend() # LRU cached instance


async def get_superuser(
    self, # Because it will a method of instance.
    current_user: dict = Depends(authentication.get_current_user), # instance.method notation is now available.
    conn: AsyncConnection = Depends(engine_connect),
) -> dict:
    ...

authentication.get_superuser = get_superuser.__get__(authentication)

Now I can use method dependency in API function:

Depends(authentication.get_superuser)

It must be ugly and not an elegant solution, but I am satisfied with authentication methods and dependencies which are living together in a class.

Thank you.