Adds RequestIDHandler function to RequestID middleware

middleware/request_id.go

@@ -14,6 +14,9 @@ type (
 		// Generator defines a function to generate an ID.
 		// Optional. Default value random.String(32).
 		Generator func() string
+
+		// RequestIDHandler defines a function which is executed for a request id.
+		RequestIDHandler func(echo.Context, string)
 	}
 )
 
@@ -53,6 +56,9 @@ func RequestIDWithConfig(config RequestIDConfig) echo.MiddlewareFunc {
 				rid = config.Generator()
 			}
 			res.Header().Set(echo.HeaderXRequestID, rid)
+			if config.RequestIDHandler != nil {
+				config.RequestIDHandler(c, rid)
+			}
 
 			return next(c)
 		}

middleware/request_id_test.go

@@ -23,13 +23,20 @@ func TestRequestID(t *testing.T) {
 	h(c)
 	assert.Len(t, rec.Header().Get(echo.HeaderXRequestID), 32)
 
-	// Custom generator
+	// Custom generator and handler
+	customID := "customGenerator"
+	calledHandler := false
 	rid = RequestIDWithConfig(RequestIDConfig{
-		Generator: func() string { return "customGenerator" },
+		Generator: func() string { return customID },
+		RequestIDHandler: func(_ echo.Context, id string) {
+			calledHandler = true
+			assert.Equal(t, customID, id)
+		},
 	})
 	h = rid(handler)
 	h(c)
 	assert.Equal(t, rec.Header().Get(echo.HeaderXRequestID), "customGenerator")
+	assert.True(t, calledHandler)
 }
 
 func TestRequestID_IDNotAltered(t *testing.T) {