Db returns a *gorm.DB based on tenant queried from ctx.

Done returns a func() stored on ctx under the key model.CTX_DONE.

Err responds the request stored on ctx with err.Error() and status http.StatusInternalServerError.

Res returns http.ResponseWriter stored on ctx under key model.CTX_RES.

SessionID returns the session identifier of the request stored on context.

Tenant returns the tenant defined in model.Session stored on ctx.

Vars returns the mux.Vars from the *http.Request stored on ctx.