NodeJs cat server empty JSON output issue - json

Question

I a beginner following a nodejs tutorial.
From said tutorial, I generated the following code:
[Index.js]
var express = require('express');
var app = express();
var bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
extended: true
}));
var cats = require('./cats.js')(app);
var server = app.listen(3000, function(){
console.log('Server running at http://127.0.0.1/3000');
});
[Cat.js]
var _ = require('lodash');
module.exports = function(app){
_cats = [];
/*
Create
*/
app.post('/cat', function(req, res){
console.log('Testing: ' + req.body);
res.json({info: 'Cat created successfully!'});
});
/*
Read
*/
app.get('/cat', function(req, res){
res.send(_cats);
});
.
.
.
.
When I start the node script, and post some json cat data as described in the tutorial, my web browser displays empty json brackets for each json input I made.
Can anyone tell me what I missed or I'm doing wrong? Why do I get empty JSON brackets instead of my cat data printed out?
I'm an utter newbie at NodeJS so I apologise if I have not described issues adequately.
UPDATE:
I'm using the Postman Chrome extension to POST json, {'name':'sam','age':'1','type':'alley'} to http://localhost:3000/cat.
The tutorial I'm following is on PluralSight. I don't think it's accessible without an account but they do offer a couple of days free to get you started.

Answer 1

Take a look at this working sample:
var express = require('express');
var app = express();
var cats = [];
var counter = 1;
app.post('/cat', function (req, res) {
cats.push({id: counter, name: 'Jacklyn'});
counter++;
res.json({info:'cat created successfully'});
});
app.get('/cat', function(req, res) {
res.json(cats);
});
app.listen(8888);
You need to send at least one POST request in order to have a cat in the array and after each new POST request the amount of cats will increase.

Answer 2

It's because the code you posted does not update the _cats array. The code for post handler should be:
app.post('/cat', function(req, res){
console.log('Testing: ' + req.body);
_cats.push(req.body); // This is the missing line
res.json({info: 'Cat created successfully!'});
});
Here I assume that the body contains a single object and it is already parsed. If not, you can add required manipulations...
Edit
It seems that the request body should be parsed. The express framework has an additional module, the body-parser, which is used for this purpose:
var bodyParser = require('body-parser');
app.use(bodyParser.json()); // this will parse json requests
For more information, see bodyParser on GitHub.