Ability to map values from context

[benbender]

Problem statement:
I'm building an API. A portion of that said API is used for administrative tasks and some other part for endusers. I've got them separated by url.
I'm having a usecase which returns the data of a single user.
I would like to reuse this usecase in both portions of the api with a clean interface to do so.

In case of a user accessing this usecase (f.e. on a route "/user-info") I'm having a middleware which authenticates the user and provides his/her ID down the chain via context.

In case of the admin accessing this usecase (f.e. on a route "/admin/users/{userID}") the id of a user is provided via url-path.

To be able to reuse that usecase in both cases it would be needed to rewrite the mapping (which is, I believe, already possible) and to map the value from ctx to the usecase (which is a new request afaik).