Node.js/http express post 方法失败，出现 404

Question

I used node.js express to create an api server. However the post method failed. I bevelieve It's my fault since it's very simple, but I can't pick it out. Any help would be appreciated. The following is the code:

var express = require('express');
const app = express();
app.use(express.json());
app.use(express.urlencoded({ extended: true }));
app.use(function (req, res, next) {
    var err = new Error('Not Found');
    err.status = 404;
    next(err);
});
app.use(function (err, req, res, next) {
    res.status(err.status || 500);
    res.json({
        message: err.message,
        error: err
    });
});
app.post('/chat', (req, res) => {
    const data = req.body.data;
    console.log('/chat---------------', data);
    res.status(200).send();
});
app.listen(3000, () => console.log(`Chat app listening!`));

And I tested the api with curl as the following:

curl -X POST http://localhost:3000/chat -H "Content-Type: application/json" -d '{"abc":"cde"}'

And the result displayed as 404. Where is the bug?

Answer 1

It's because you added the middleware for 404 before your endpoint, which handles all API calls.

Here is the correct order.

var express = require('express');
const app = express();
app.use(express.json());
app.use(express.urlencoded({ extended: true }));


app.post('/chat', (req, res) => {
    const data = req.body.data;
    console.log('/chat---------------', data);
    res.status(200).send();
});

app.use(function (err, req, res, next) {
  res.status(err.status || 500);
  res.json({
      message: err.message,
      error: err
  });
});

app.use(function (req, res, next) {
  var err = new Error('Not Found');
  err.status = 404;
  next(err);
});

app.listen(3000, () => console.log(`Chat app listening!`));