Little change of session API + Update examples

Former-commit-id: e8c58b186acf1c8932af6e886dae7035f4d581c1

_examples/sessions/database/main.go

@@ -65,5 +65,10 @@ func main() {
 		sess.Destroy(ctx)
 	})
 
+	app.Get("/update", func(ctx context.Context) {
+		// updates expire date with a new date
+		sess.ShiftExpiraton(ctx)
+	})
+
 	app.Run(iris.Addr(":8080"))
 }

_examples/sessions/securecookie/main.go

@@ -62,10 +62,16 @@ func newApp() *iris.Application {
 		mySessions.Start(ctx).Clear()
 	})
 
+	app.Get("/update", func(ctx context.Context) {
+		// updates expire date with a new date
+		mySessions.ShiftExpiraton(ctx)
+	})
+
 	app.Get("/destroy", func(ctx context.Context) {
 		//destroy, removes the entire session data and cookie
 		mySessions.Destroy(ctx)
-	}) // Note about destroy:
+	})
+	// Note about destroy:
 	//
 	// You can destroy a session outside of a handler too, using the:
 	// mySessions.DestroyByID

_examples/sessions/standalone/main.go

@@ -69,6 +69,11 @@ func main() {
 		sess.Start(ctx).Clear()
 	})
 
+	app.Get("/update", func(ctx context.Context) {
+		// updates expire date
+		sess.ShiftExpiraton(ctx)
+	})
+
 	app.Get("/destroy", func(ctx context.Context) {
 
 		//destroy, removes the entire session data and cookie

sessions/sessions.go

@@ -119,14 +119,19 @@ func (s *Sessions) Start(ctx context.Context) *Session {
 }
 
 // ShiftExpiraton move the expire date of a session to a new date by using session default timeout configuration
-func (s *Sessions) ShiftExpiraton(ctx context.Context, sid string) {
-	s.UpdateExpiraton(ctx, sid, s.config.Expires)
+func (s *Sessions) ShiftExpiraton(ctx context.Context) {
+	s.UpdateExpiraton(ctx, s.config.Expires)
 }
 
 // UpdateExpiraton change expire date of a session to a new date by using timeout value passed by `expires` parameter
-func (s *Sessions) UpdateExpiraton(ctx context.Context, sid string, expires time.Duration) {
-	if s.provider.UpdateExpiraton(sid, expires) {
-		s.updateCookie(sid, ctx, expires)
+func (s *Sessions) UpdateExpiraton(ctx context.Context, expires time.Duration) {
+	cookieValue := GetCookie(ctx, s.config.Cookie)
+
+	if cookieValue != "" {
+		sid := s.decodeCookieValue(cookieValue)
+		if s.provider.UpdateExpiraton(sid, expires) {
+			s.updateCookie(sid, ctx, expires)
+		}
 	}
 }