How to get JSON data from url in Node.js with Express

Question

I am trying to get the a Json object from a url using Express:

this is my code:

app.get('/device/:id', (req, res, next) => {
     console.log('device: ' + req.params.id + ' Request received');
     let parsedContent = JSON.parse(req.query);
     //res.status(201).send('success');
 });

this my url:

http://localhost:4001/device/1?{"type":"fridge","pcb"=2.4}

I get an error on the parsing line.

Here is the error as requested:

SyntaxError: Unexpected token o in JSON at position 1
  at JSON.parse (<anonymous>)

I have also tried this:

app.get('/device/:id', (req, res, next) => {
    let query = url.parse(req.url).query;
    if( query ) {
        let parsedContent = JSON.parse(decodeURIComponent(query));
    }
});

With this url:

http://localhost:4001/device/1??type=fridge&pcb=2.4

Still the same issue.

could you add more information and what error you get

pr0p
– pr0p

2018-07-02 15:55:14 +00:00
Commented Jul 2, 2018 at 15:55 — pr0p
– pr0p, Commented Jul 2, 2018 at 15:55
Also it is device and not dev

pr0p
– pr0p

2018-07-02 15:55:58 +00:00
Commented Jul 2, 2018 at 15:55 — pr0p
– pr0p, Commented Jul 2, 2018 at 15:55

MjZac · Accepted Answer · 2018-07-03 08:05:36Z

2

If you want to send json data in request, it is better to make use of POST request. Then the server should accept post data.

var bodyParser = require('body-parser')
app.use( bodyParser.json() );       // to support JSON-encoded bodies
app.use(bodyParser.urlencoded({     // to support URL-encoded bodies
    extended: true
}));

...

app.post('/device/:id', (req, res, next) => {
   console.log('device: ' + req.params.id + ' Request received');
   let parsedContent = JSON.parse(req.query);
   let payload = req.body.payload; // your json data
   //res.status(201).send('success');
});

if you insist on using GET request, you need to urlencode the query parameters before sending it to the server.

http://localhost:4001/device/1?payload=%7B%22type%22%3A%22fridge%22%2C%22pcb%22%3D2.4%7D

In your server code, you can access it as let payload = JSON.parse(req.query.payload)

answered Jul 3, 2018 at 8:05

MjZac

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3 Comments

user7002255 Over a year ago

Hello and thank you for your reply. I think I like your approach more.

l00k Over a year ago

downvote: POST has deferent semantic. Also consider caching / proxy handling.

MjZac Over a year ago

@l00k Why? The answer contains methods to use in both POST and GET. Also why introduce things that OP doesn't require. You could always add to the answer if you have any points.

pr0p · Accepted Answer · 2018-07-02 16:04:06Z

1

Your url should be :

http://localhost:4001/device/1?type=fridge&pcb=2.4

You can't write a query as you did in your url. It has to follow the format.

? depicts the start of the query. Then you put the key value pair as key=value and if you have many of them then use single &

So ?key1=val1&key2=val2&key3=val3 ....

Your req.query will be :

{"type":"fridge","pcb"=2.4}

edited Jul 2, 2018 at 16:04

answered Jul 2, 2018 at 15:58

pr0p

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2 Comments

user7002255 Over a year ago

hello, and thanks for the quick reply. I need to send a Json object in json format. this is meant to be a http request not a not url.

pr0p Over a year ago

If you pass it this way you do get your object as a json

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