JavaScript / Express：TypeError：res.json不是函数

Question

My frontend is successfully connected to my server; however, my initial fetch request is throwing a:

GET http://localhost:8080/events net::ERR_EMPTY_RESPONSE

Every time I perform an action, my server is throwing:

UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): TypeError: res.json is not a function

Here is my server.js:

// Require and initiate Express
const express = require('express');
const app = express();

//Import controllers, db and bodyParser
const controller = require('./controllers');
const bodyParser = require('body-parser');
const cors = require('cors');
require('./db');


//Add bodyParser & cors middleware
app.use(cors());
app.use(bodyParser.json());

//Define routes for List Events, Add Event, and Delete Event
app.get('/events', controller.listEvents);
app.post('/events', controller.addEvent);
app.delete('/events/:id', controller.deleteEvent);


//Initiate server on port 8080
app.listen(8080, () => {
  console.log('Server is listening on http://localhost:8080');
})

And here is the GET in my controller.js:

//Gets list of events
exports.listEvents = (req, res) => {
  Event.find()
  .then(events => {
    res.json(events);
  })
}

Any suggestions would be greatly received!

Answer 1

The Event.find() promise is failing. There's no catch block to catch the error. That's the reason for UnhandledPromiseRejectionWarning

You can respond with error like this:

exports.listEvents = (req, res, next) => {
  Event.find()
  .then(events => {
    res.json(events);
  }).catch(err => { console.log(err); next(err) });
}

And add the error handler in the server.js like this:

app.use((err, req, res, next) => {
  res.status(err.status || 500).json({
    message: err.message || "Something went wrong. Please try again",
    status: err.status || 500
  });
});

This won't solve your issue, just tells you what the issue is.