Set default value for URL parameter in HTTP GET in node.js

Question

I am using node.js restify.

I have a HTTP GET request that looks like this;

http://127.0.0.1//read_val?XXX=123&YYY=456&ZZZ=789

In my handling function, to retrieve the URL parameters, the relevant code will be like this;

var api_get_func = function (app, url_path) {
    function respond(req, res, next) {
        var XXX= req.query.XXX;
        var YYY = req.query.YYY;
        var ZZZ = req.query.ZZZ;

        //SQL query ...
        return next();
    }

    app.get(url_path, respond);
}

Now, what if I have a HTTP GET function like this below

http://127.0.0.1//read_val?XXX=123&YYY=456

The ZZZ parameter is not provided in the URL. How do I modify the code such that ZZZ will use a default value of, say, 111?

Kevin Reilly · Accepted Answer · 2017-04-05T08:16:30.660

If just want to check if something is provided, then you could just do:

var ZZZ = req.query.ZZZ || 111;

But... GET parameters are query strings, so we probably want to make sure it is a number.

if (!parseInt(req.query.ZZZ)) {
  req.query.ZZZ = 111;
}

Or if you want to get ternary with it:

req.query.ZZZ = parseInt(req.query.ZZZ) ? req.query.ZZZ : 111;

Do note that the other parameters are a string and that this default is being set as a number. So, you might want '111' as opposed to 111. Also, you can parseInt all of your query strings or toString them all if they are all a number, just try to make sure they all remain the same expected type. Unless of course these are all strings of text, in which case ignore all this.

`''` is not truthy; the rest of this follows though – milkandtang Mar 21 '16 at 03:35 — milkandtang, Mar 21 '16 at 03:35

score 2 · Answer 2 · answered Feb 25 '16 at 06:17

2

var api_get_func = function (app, url_path) {
    function respond(req, res, next) {
        var XXX= req.query.XXX;
        var YYY = req.query.YYY;
        var ZZZ = req.query.ZZZ || <YOUR DEFAULT VALUE>;

        //SQL query ...
        return next();
    }`enter code here`

    app.get(url_path, respond);
}

answered Feb 25 '16 at 06:17

Atul Agrawal

1,474
5
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looks awesomely simple. Is this solution applicable only to node.js restify? – guagay_wk Feb 25 '16 at 06:18
1

It is a general JavaScript thing. It is similar to doing `if (req.query.ZZZ || 111)` as the truthy value is returned. – Kevin Reilly Feb 25 '16 at 06:21
1

you can use this as well if this value can be 0 then you can use simple tertiary operator(?:) as like – Atul Agrawal Feb 25 '16 at 06:22
1

req.query.ZZZ === ' undefined' ? 'default ' : req.query.ZZZ – Atul Agrawal Feb 25 '16 at 06:23
@Atul Agrawal, your answer is good but I think Kevin Reilly's is better. Sorry, I can only mark one answer as the answer. – guagay_wk Feb 25 '16 at 06:28

Mike Brian Olivera · Answer 3 · 2020-04-24T07:43:37.660

1

In one line, the best way is this:

let limit = parseInt(req.query.limit || 0);
let page = parseInt(req.query.pagina || 1);
let offset = page * limit

Because you put a default value then you parse the content.

req.query.limit || 0

This line check if the content was sent, if not, put 0 as default value

edited Apr 24 '20 at 07:43

answered Apr 23 '20 at 18:22

Mike Brian Olivera

1,414
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Beware that parseInt might return NaN values if the req.query.limit is "abc" as example. – Jun 16 '20 at 06:55

Set default value for URL parameter in HTTP GET in node.js

3 Answers3