Custom Middleware Logging

Demonstrates the middleware escape hatch: a hand-written app.use(...) request logger placed ahead of the JSON body parser.

Nodes involved: middleware.customCode, plus the standard express.* wiring and a route attached to a logic.handlerFunction/handler.sendJson pair.

middleware.customCode wraps its raw code in app.use((req, res, next) => { ... }) — call next() to continue the chain, or respond directly to end it there. This example just logs METHOD path for every request before falling through to a trivial GET /ping route.

Generated server.js

const express = require("express");

const app = express();

function handler(req, res, next) {
  res.status(200).json({ pong: true });
}

app.use((req, res, next) => {
  console.log(`${req.method} ${req.path}`);
  next();
});

app.use(express.json());

app.get("/ping", handler);

app.listen(3003, () => {
  console.log("Server running on port 3003");
});

Run it

npx visual-node examples/03-custom-middleware-logging

curl http://localhost:3003/ping
# {"pong":true}

Watch the server's console output — it prints GET /ping for the request above, logged entirely from the custom middleware node.