Express JS use async function on requests

Question

app.use(async function(req, res, next) {
    try {
        var myres = await new Promise((resolve, reject) => {
            mysql_connection.query(\"select * from         


        

Answer 1

Async await can be used with no problem for DB queries. You could use try catch however there is a more elegant solution which allows you to use the error handling middleware which express offers:

You wrap your middleware with this function:

const asyncMiddleware = fn =>
  (req, res, next) => {
    Promise.resolve(fn(req, res, next))
      .catch(next);
  };

Then you can use it in the following manner:

const asyncMiddleware = require('./utils/asyncMiddleware');

router.get('/', asyncMiddleware(async (req, res, next) => {
    /* 
      if there is an error thrown in getUserFromDb, asyncMiddleware
      will pass it to next() and express will handle the error;
    */
    const user = await getUserFromDb({ id: req.params.id })
    res.json(user);
}));

If an error is thrown the control will be handed over to the error handling middleware which is middlware which has four arguments like this:

app.use(function (err, req, res, next) {
   // your error code
})