CODEWITHSUNDEEP
node.jsexpress
Ernani
Ernani

Reputation: 1059

Static variable through multiple API calls with Express

I want to have a variable that could keep its value from the last API call. That is, every time I call /api, it increments a variable count by 1, and when I call /value, it shows the value of count. So if I call /api 3 times and then call /value, it should print 3.

Is it possible? To keep the value of the variable throw multiple API calls? I'm trying to avoid access files and databases, I'm sure I can do that with those.

Upvotes: 5

Views: 5049

Answers (4)

user5383152
user5383152

Reputation:

You could create a module that you can require at any part of your app.

For example, you have a module in counter.js defined as

var counter = function() {
    var count = 0;

    this.addCount = function() {
        count++
    }

    this.getCount = function() {
        return count;
    }
}

counter.instance = null;

counter.getInstance = function() {
    if (this.instance === null) {
        this.instance = new counter();
    }

    return this.instance;
}

module.exports = counter.getInstance();

Now, you can use it in the server.js like this

var express = require('express');
var app = express();

var bodyParser = require('body-parser');
var morgan = require('morgan');

app.use(morgan('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));

var counter = require('./counter.js');
app.get('/value', function(req, res, next) {
    res.send('Count = ' + counter.getCount());
});

app.use('/api', require('./api.js'));

var server = app.listen(3000, function () {
    var host = server.address().address;
    var port = server.address().port;
    console.log("Server listening at http://%s:%s", host, port);
});

And in your api.js like this

var express = require('express');
var router = express.Router();

var counter = require('./counter.js');

router.get('/', function(req, res, next) {
    counter.addCount();
    res.send('API Called');
});

module.exports = router;

Upvotes: 4

QwertyKing
QwertyKing

Reputation: 64

You can set a global variable like this outside of your api...

var count = 0;

Then make an api like this...

app.get('/value', function(req, res) {
  res.send(count);
})
app.get('/api', function(req, res) {
  count = count + 1;
  res.send();
})

The above example is using the express framework. If you aren't use it, you should get used to it. It's a great framework!

Upvotes: 0

Jose Hermosilla Rodrigo
Jose Hermosilla Rodrigo

Reputation: 3683

If you create the variable in the top-level of your js file it will be global for that js file. Also if your /api and /value route handlers are in diferent files you can create a global variable that it will be visible in all your other files. But you have to take in count that no other variables should have the same name that your global variable, because it will be overwritted. Here you have a good related post : How to use global variable in node.js?

var count = 0;

app.get('/api', function(req, res) {
  count += 1;
  res.send();
}

app.get('/value', function(req, res) {
  res.send(count);
}

Upvotes: 7

Saurabh Sharma
Saurabh Sharma

Reputation: 54

Yes, Use can use express session or any other session for the same, or global variable

Upvotes: -1

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