Add echo.OnAddRouteHandler field. As name says - this handler is called when new route is registered.

Author: aldas

echo.go

@@ -61,20 +61,28 @@ import (
 
 type (
 // Echo is the top-level framework instance.
+//
+// Goroutine safety: Do not mutate Echo instance fields after server has started. Accessing these
+// fields from handlers/middlewares and changing field values at the same time leads to data-races.
+// Same rule applies to adding new routes after server has been started - Adding a route is not Goroutine safe action.
 Echo struct {
 filesystem
 common
 // startupMutex is mutex to lock Echo instance access during server configuration and startup. Useful for to get
 // listener address info (on which interface/port was listener binded) without having data races.
-startupMutex sync.RWMutex
+startupMutex sync.RWMutex
+colorer *color.Color
+
+// premiddleware are middlewares that are run before routing is done. In case pre-middleware returns an error router
+// will not be called at all and execution ends up in global error handler.
+premiddleware []MiddlewareFunc
+middleware []MiddlewareFunc
+maxParam *int
+router *Router
+routers map[string]*Router
+pool sync.Pool
+
 StdLogger *stdLog.Logger
-colorer *color.Color
-premiddleware []MiddlewareFunc
-middleware []MiddlewareFunc
-maxParam *int
-router *Router
-routers map[string]*Router
-pool sync.Pool
 Server *http.Server
 TLSServer *http.Server
 Listener net.Listener
@@ -92,6 +100,9 @@ type (
 Logger Logger
 IPExtractor IPExtractor
 ListenerNetwork string
+
+// OnAddRouteHandler is called when Echo adds new route to specific host router.
+OnAddRouteHandler func(host string, route Route, handler HandlerFunc, middleware []MiddlewareFunc)
 }
 
 // Route contains a handler and information for matching against requests.
@@ -526,14 +537,20 @@ func (e *Echo) File(path, file string, m ...MiddlewareFunc) *Route {
 return e.file(path, file, e.GET, m...)
 }
 
-func (e *Echo) add(host, method, path string, handler HandlerFunc, middleware ...MiddlewareFunc) *Route {
+func (e *Echo) add(host, method, path string, handler HandlerFunc, middlewares ...MiddlewareFunc) *Route {
 router := e.findRouter(host)
 //FIXME: when handler+middleware are both nil ... make it behave like handler removal
 name := handlerName(handler)
-return router.add(method, path, name, func(c Context) error {
-h := applyMiddleware(handler, middleware...)
+route := router.add(method, path, name, func(c Context) error {
+h := applyMiddleware(handler, middlewares...)
 return h(c)
 })
+
+if e.OnAddRouteHandler != nil {
+e.OnAddRouteHandler(host, *route, handler, middlewares)
+}
+
+return route
 }
 
 // Add registers a new route for an HTTP method and path with matching handler

echo_test.go

@@ -1478,6 +1478,44 @@ func TestEchoListenerNetworkInvalid(t *testing.T) {
 assert.Equal(t, ErrInvalidListenerNetwork, e.Start(":1323"))
 }
 
+func TestEcho_OnAddRouteHandler(t *testing.T) {
+type rr struct {
+host string
+route Route
+handler HandlerFunc
+middleware []MiddlewareFunc
+}
+dummyHandler := func(Context) error { return nil }
+e := New()
+
+added := make([]rr, 0)
+e.OnAddRouteHandler = func(host string, route Route, handler HandlerFunc, middleware []MiddlewareFunc) {
+added = append(added, rr{
+host: host,
+route: route,
+handler: handler,
+middleware: middleware,
+})
+}
+
+e.GET("/static", NotFoundHandler)
+e.Host("domain.site").GET("/static/*", dummyHandler, func(next HandlerFunc) HandlerFunc {
+return func(c Context) error {
+return next(c)
+}
+})
+
+assert.Len(t, added, 2)
+
+assert.Equal(t, "", added[0].host)
+assert.Equal(t, Route{Method: http.MethodGet, Path: "/static", Name: "github.com/labstack/echo/v4.glob..func1"}, added[0].route)
+assert.Len(t, added[0].middleware, 0)
+
+assert.Equal(t, "domain.site", added[1].host)
+assert.Equal(t, Route{Method: http.MethodGet, Path: "/static/*", Name: "github.com/labstack/echo/v4.TestEcho_OnAddRouteHandler.func1"}, added[1].route)
+assert.Len(t, added[1].middleware, 1)
+}
+
 func TestEchoReverse(t *testing.T) {
 e := New()
 dummyHandler := func(Context) error { return nil }