How do I check Content-Type using ExpressJS?

Question

I have a pretty basic RESTful API so far, and my Express app is configured like so:

app.configure(function () {   app.use(express.static(__dirname + '/public'));   app.use(express.logger('dev'));   app.use(express.bodyParser()); });  app.post('/api/vehicles', vehicles.addVehicle); 

How/where can I add middleware that stops a request from reaching my app.post and app.get if the content type is not application/json?

The middleware should only stop a request with improper content-type to a url that begins with /api/.

Answer 1

If you're using Express 4.0 or higher, you can call request.is() on requests from your handlers to filter request content type. For example:

app.use('/api/', (req, res, next) => {     if (!req.is('application/json')) {         // Send error here         res.send(400);     } else {         // Do logic here     } }); 

Answer 2

This mounts the middleware at /api/ (as a prefix) and checks the content type:

app.use('/api/', function(req, res, next) {   var contype = req.headers['content-type'];   if (!contype || contype.indexOf('application/json') !== 0)     return res.send(400);   next(); });