POST上的404 for nodejs / express应用

Question

I've been following a tutorial online, but modifying it for my own project. Get requests to api/posts work fine, but Post requests lead to 404 and 'Error: Can't set headers after they are sent.'. I can't work out why this is.

'use strict'

const express = require('express');
const mongoose = require('mongoose');
const bodyParser = require('body-parser');
const Post = require('./models/post_schema');

const app = express();
const router = express.Router();

const port = process.env.API_PORT || 3000;

mongoose.connect('mongodb://REDACTED');

app.use(bodyParser.urlencoded({extend: true}));
app.use(bodyParser.json());

app.use(function(req, res, next) {
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.setHeader('Access-Control-Allow-Credentials', 'true');
    res.setHeader('Access-Control-Allow-Methods', 'GET,HEAD,OPTIONS,POST,PUT,DELETE');
    res.setHeader('Access-Control-Allow-Headers', 'Access-Control-Allow-Headers, Origin,Accept, X-Requested-With, Content-Type, Access-Control-Request-Method, Access-Control-Request-Headers');
    res.setHeader('Cache-Control', 'no-cache');
    next();
});

router.get('/', function(req, res) {
    res.json({ message: 'API Initlialised'});
});

router.route('/posts')
    .get(function(req, res) {
        Post.find(function(err, posts) {
            if (err) {res.send(err)}
            res.json(posts)
        })
    })
    .post(function(req, res) {
        const post = new Post();
        post.title = req.body.title;
        post.text = req.body.text;

        post.save(function(err) {
            if (err) {res.send(err)};
            res.json({ message: 'Post added!'});
        });
    });



app.use('/api', router);

app.listen(port, function() {
    console.log(`api running on port ${port}`)
})

I've gone through the express documentation, but can't find a solution. Any help would be appreciated.

Answer 1

Your server could send 2 http response, if an error occurred on the save method, I think that's why you get Can't set headers after they are sent. , try to use return statement to stop the remaining code from executing or use else clause:

post.save(function(err) {
    if (err) {
        return res.json({ success: false, error: err.message });
    }

    res.json({ message: 'Post added!'});
});

Answer 2

This might do the trick!

router.route('/posts')
    .get(function(req, res) {
        Post.find(function(err, posts) {
            if (err) return res.send(err);
            return res.json(posts)
        })
    })
    .post(function(req, res) {
        const post = new Post();
        post.title = req.body.title;
        post.text = req.body.text;

        post.save(function(err) {
            if (err) return res.send(err);
            return res.json({ message: 'Post added!'});
        });
    });