app.js

app.get("/user", function(req, res) {
  User.find({})
    .then(data => {
      res.status(200).send(data);
    })
    .catch(err => res.send("Something Went Wrong"));
});

app.post("/user", function(req, res) {
  const name = req.body.name;
  const age = req.body.age;

  const user = User({
    name,
    age
  });
  user
    .save()
    .then(data => res.status(200).send(data))
    .catch(err => res.send("Error occured"));
});

app.put("/user/:id", function(req, res) {
  const name = req.body.name;
  const age = req.body.age;

  User.findByIdAndUpdate(
    { _id: req.params.id },
    {
      $set: {
        name,age
      }
    },
    { new: true }
  )
    .then(data => res.send(data))
    .catch(err => res.send(err));
});

app.delete("/user/:id", function(req, res) {
  User.findByIdAndRemove({ _id: req.params.id })
    .then(data => res.send(data))
    .catch(err => res.send("Error Occured "));
});

module.exports.handler = serverless(app);