nodejs (express) is it possible to have case insensitive querystring?

Question

It seems that querystring is case sensitive. Is it possible to have a case insensitive querystring?

If my url has ?Id=10, accessing req.query.id returns undefined.

Answer 1

It's not possible as-is, but you could insert a very simple middleware which would, for instance, lowercase all keys in req.query:

// insert this before your routes
app.use(function(req, res, next) {
  for (var key in req.query)
  { 
    req.query[key.toLowerCase()] = req.query[key];
  }
  next();
});

Answer 2

With the solution proposed by Robert, be aware that whenever you read from req.query, you will need to use lowercased keys. This makes future additions to your API error prone.

Here is an alternative piece of middleware, using a Proxy object to modify the behavior of req.query[...], so that lookups are case insensitive:

app.use((req, res, next) => {
  req.query = new Proxy(req.query, {
    get: (target, name) => target[Object.keys(target)
      .find(key => key.toLowerCase() === name.toLowerCase())]
  })

  next();
});

Besides being less error prone, this approach also leaves the req.query intact for enumerating operations, where the original solution would potentially create duplicate key/value pairs.