Axios OPTIONS instead of POST Request. Express Rest API (CORS) - rest

Question

Im trying to use Axios (and VueJs) to make a Cross Origin POST Request to my Rest Api (running on localhost). Instead of doing a POST request, it actually does a OPTIONS request to my Rest Api. This circumvents a middleware function that checks for a token and return 403.
This is the login function
router.post('/login', (req, res) => {
User.authUser(req.body, (err, user) => {
var passwordIsValid = bcrypt.compareSync(req.body.password, user.password);
if (err) throw err;
if (!user) {
res.json({ success: false, message: 'User nicht gefunden' });
} else if (user) {
if (!passwordIsValid) {
res.json({ success: false, message: 'Falsches Passwort' });
} else {
const payload = {
admin: user.admin
};
var token = jwt.sign(payload, config.secret, {
expiresIn: 86400
});
res.json({success: true, message: 'Token!', token: token});
}
}
})
});
How can I get Axios to make a proper POST request? I tried this hack, because I first thought the OPTIONS Request was just a preflight, but there is no request after I return 200 (or 204)
CORS Middleware:
app.use(function(req, res, next) { //set Response Headers
res.setHeader('Access-Control-Allow-Origin', '*');
res.setHeader('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
if ('OPTIONS' == req.method) {
res.send(204);
}
else {
next();
}
});

Answer 1

Axios will sometimes send an OPTIONS request as part of a cors preflight if it doesn't know the Content-Type of a request.
You can get explicitly specify the Content-Type when you build the request, and then it should send your POST request as expected.
Instead of
axios.post(url, params), try:
axios.post(url, params, {
headers: { 'Content-Type': 'application/x-www-form-urlencoded' }
})