Three req.param() uses and how they interact with app.param()

app.param() scenarios

var express = require('express');
var app = module.exports = express.createServer();

app.configure(function(){
  app.use(express.bodyParser());
  app.use(express.methodOverride());
  app.use(app.router);
});

app.param(':id', function(req, res, next, val) {
  console.log("Inside app.param with val = " + val);
  next();
});

// Test 1:  param in URL -- *does* call app.param() function
// curl http://localhost:3000/test/foo1
app.get('/test/:id', function(req, res){
  res.send();
});

// Test 2:  query parameter -- does not call app.param()
// curl http://localhost:3000/test?id=foo2
app.get('/test', function(req, res){
  res.send();
});

// Test 3:  form element -- does not call app.param()
// curl -d id=foo3 http://localhost:3000/test
app.post('/test', function(req, res){
  res.send();
});

app.listen(3000);