Replacement for req.param() that is deprecated in Express 4

Question

We are migrating from ExpressJS 3 to ExpressJS 4, and we noted that the following APIs are being deprecated:

req.param(fieldName)
req.param(fieldName, defaultValue)

Is there a middleware that brings these APIs back, like other APIs that were 'externalized' from express to independent modules ?

EDITED: Clarification - The need is an API that provides an abstracted generic access to a parameter, regardless to if it is a path-parameter, a query-string parameter, or a body field.

Answer 1

Based on Express Documentation, we should use like this

On express 3

req.param(fieldName)

On express 4

req.params.fieldName

Personally i prefer req.params.fieldName instead req.param(fieldName)

Answer 2

Why would you want to bring it back? There's a reason that it's been deprecated and as such you should probably move away from it.

The discussion on why they are deprecating the API is available at their issue tracker as #2440.

The function is a quick and dirty way to get a parameter value from either req.params, req.body or req.query. This could of course cause trouble in some cases, which is why they are removing it. See the function for yourself here.

If you are just using the function for url parameters, you can just replace it with this a check for req.query['smth'] or 'default':

var param_old = req.param('test', 'default');
var param_new = req.query['test'] || 'default';

(Please note that an empty string is evaluated to false, so they are not actually 100% equal. What you want is of course up to you, but for the most part it shouldn't matter.)

Answer 3

Ok, after reading the threads given in references by @Ineentho, we decided to come up with the following answer:

https://github.com/osher/request-param

A connect/express middleware to enable back the req.param(name,default) API deprecated in express 4

The middleware does not only brings back the goo'old functionality. It also lets you customize the order of collections from which params are retrieved , both as default rule, and as per-call :-)

Have fun!