How to actually _load_ the resource with Guardian

Guardian, like all auth libraries in all languages, is tough to wrap my head around.

I know there is a plug in the pipeline called plug Guardian.Plug.LoadResource. I know there is a function called Guardian.Plug.current_resource(conn) that takes the conn and returns that returns the resource placed in the conn by the Guardian.Plug.LoadResource plug.

What I don't know is how the LoadResource plug knows what resource to get.

In Guardian, you configure the pipeline with:

use Guardian.Plug.Pipeline, otp_app: :my_app,
                              module: GuardianImpl,
                              error_handler: ErrorHandler

The GuardianImpl is a module that uses the Guardian behaviour.

The Guardian behaviour has a callback resource_from_claims that might be implemented like this:

def resource_from_claims(claims) do
  {:ok, Repo.get(User, claims["sub"])}
end

So when you need to modify how you load the resource, you should look to see how the resource_from_claims callback is implemented.

Read more here.