How to handle hybrid storage from external libraries

[dlpetrie]

Hello, I really appreciate your article and have been trying to implement the approach as it makes a lot of sense. I also watched the Brian Ketelsen talk that referred to it as well.

Where I am struggling right now is when a library uses a hybrid approach to storage. For example, I am using the https://github.com/alexedwards/scs library for session with redis as a backend storage. So this is using a combination of http cookies and redis for tracking the session.

I create a session interface in my domain type package

package app

// SessionUser represents a user who has authenticated into the application.
type SessionUser struct {
	ID        string
	Email     string
	FirstName string
	LastName  string
}

// SessionService represents a service for managing a user session.
type SessionService interface {
	Get(ctx context.Context) (*SessionUser, error)
	Save(ctx context.Context, state *SessionUser) error
	Delete(ctx context.Context) error
}

But where do I handle the implementation for this? Do I handle it in the http package because it uses cookies? The redis package because it uses redis? Or is it another packaged called scs to where scs becomes the dependency I'm referencing.

[benbjohnson]

But where do I handle the implementation for this? Do I handle it in the http package because it uses cookies? The redis package because it uses redis? Or is it another packaged called scs to where scs becomes the dependency I'm referencing.

If you're only managing sessions in the http layer then I think you can avoid a service interface definition entirely and just use the scs library internally in the http package.

If you are managing sessions outside the http layer, then it doesn't matter too much about which package you place it into so long as its accessible. The main benefit to having the SessionService interface would be to have swappable implementations but that's not typical for most applications.