Passing route control with optional parameter after root in express?

Question

I\'m working on a simple url-shortening app and have the following express routes:

app.get(\'/\', function(req, res){
  res.render(\'index\', {
    link: nul         


        

Answer 1

That would work depending on what client.get does when passed undefined as its first parameter.

Something like this would be safer:

app.get('/:key?', function(req, res, next) {
    var key = req.params.key;
    if (!key) {
        next();
        return;
    }
    client.get(key, function(err, reply) {
        if(client.get(reply)) {
            res.redirect(reply);
        }
        else {
            res.render('index', {
                link: null
            });
        }
    });
});

There's no problem in calling next() inside the callback.

According to this, handlers are invoked in the order that they are added, so as long as your next route is app.get('/', ...) it will be called if there is no key.

Answer 2

Express version:

"dependencies": {
    "body-parser": "^1.19.0",
    "express": "^4.17.1"
  }

Optional parameter are very much handy, you can declare and use them easily using express:

app.get('/api/v1/tours/:cId/:pId/:batchNo?', (req, res)=>{
    console.log("category Id: "+req.params.cId);
    console.log("product ID: "+req.params.pId);
    if (req.params.batchNo){
        console.log("Batch No: "+req.params.batchNo);
    }
});

In the above code batchNo is optional. Express will count it optional because after in URL construction, I gave a '?' symbol after batchNo '/:batchNo?'

Now I can call with only categoryId and productId or with all three-parameter.

http://127.0.0.1:3000/api/v1/tours/5/10
//or
http://127.0.0.1:3000/api/v1/tours/5/10/8987