angular.js http.POST contains no data

I'm starting out learning the MEAN stack, so apologies of this is a stupid question. I'm adapting a few tutorials to my own project, and I've made a simple REST api to a database of books.

// add book and return updated list
app.post('/api/books', function(req, res) {
    console.log("New book: ", JSON.stringify(req.body, null, 4));
    Book.create({
        title: req.body.title,
        author: req.body.author,
        pageCount: 100,
    }, function(err, book) {
        if (err)
            res.send(err);

        // get and return updated list
        Book.find(function(err, books) {
            if (err)
                res.send(err);
            res.json(books);
        });
    });
});

I'm trying to use angular to interface with this, like so:

$scope.createBook = function() {
    console.log('Trying to create ', $scope.formData);
    $http({ method: 'POST', url: '/api/books', data: $scope.formData}).then(function (response) {
        $scope.formData = {};   // reset form
        console.log('CREATE Success: ', response);
    }, function (error) {
        console.log('CREATE Error: ', error);
    });
};

The output I get from the createBook-function is Trying to create – {title: "amazingTitle", author: "amazingAuthor"}, which is as it should be, but the output from the API handler is New book: {}, which is of course not what I want. I realise this might not be enough detail to go on, but where could I be going wrong here?