Facebook messenger bot error Unexpected token ' in JSON at position 0

Question

I'm trying to create a Facebook messenger bot using NodeJS and Express.

I'm following the facebook guide and when I tried to run this command

curl -H "Content-Type: application/json" -X POST "localhost:4000/" -d '{"object": "page", "entry": [{"messaging": [{"message": "TEST_MESSAGE"}]}]}'

I have got this error SyntaxError: Unexpected token ' in JSON at position 0

Here is my code:

    var express = require('express');
    var bodyParser = require('body-parser');
    var request = require("request")

    var app = express();
    var port = process.env.PORT || 4000;

    app.use(bodyParser.json());
    app.use(bodyParser.urlencoded({ extended: true }));

    app.get('/', function(req, res) {
        if (req.query['hub.verify_token'] === '22222') {
            res.send(req.query['hub.challenge']);
            console.log("GET")
            res.sendStatus(200)
        }

        console.log("Error: wrong token")
    })

    app.post('/', function(req, res) {
        messaging_events = req.body.entry[0].messaging;
        console.log("post")
        for (i = 0; i < messaging_events.length; i++) {
            event = req.body.entry[0].messaging[i];
            sender = event.sender.id;
            if (event.message && event.message.text) {
                text = event.message.text;
                sendTextMessage(sender, "Text received, echo: " + text.substring(0, 200));
            }
        }
        res.sendStatus(200);
    });

    app.listen(port, function() {
        console.log('Listening on port ' + port);
    });

    var token = "<token>";

    function sendTextMessage(sender, text) {
        messageData = {
            text: text
        }
        request({
            url: 'https://graph.facebook.com/v2.6/me/messages',
            qs: { access_token: token },
            method: 'POST',
            json: {
                recipient: { id: sender },
                message: messageData,
            }
        }, function(error, response, body) {
            if (error) {
                console.log('Error sending message: ', error);
            } else if (response.body.error) {
                console.log('Error: ', response.body.error);
            }
        });
    }

I ignored this error and started the bot. Webhooks I connected via ngrok. I'm sure that on Facebook I set everything right.But I'm not getting the message information sent to my webhook from facebook.]

Edit: '{"object": "page", "entry": [{"messaging": [{"message": "TEST_MESSAGE"}]}]}' this is the error line

Do you get a line number as well about where the error occurs? — TommyBs, Aug 08 '18 at 20:06
@EdwinBabu Can you please say me how did you set up messenger on facebook? — Roma Boyko, Aug 09 '18 at 12:26

score 4 · Answer 1 · answered Dec 12 '18 at 08:17

4

try:

curl -H "Content-Type: application/json" -X POST "localhost:4000/" -d "{""object"": ""page"", ""entry"": [{""messaging"": [{""message"": ""TEST_MESSAGE""}]}]}"

answered Dec 12 '18 at 08:17

ZephyrLee

97
10

1

provide some explanation. – Harshith Rai Dec 12 '18 at 08:36
2

In windows command prompt, we use " to quote a string instead of ', and use double quote "" to escape ", at least I got the same problem but solved by this way – ZephyrLee Dec 17 '18 at 14:23
@ZephyrLee I was having trouble with this for a while and then I managed to find this question. Thank you, the changes to the quotes worked as well with the updated version of the tutorial. https://developers.facebook.com/docs/messenger-platform/getting-started/webhook-setup – Nena Mar 12 '20 at 14:45

score 2 · Answer 2 · answered Aug 11 '19 at 17:10

try this out:

curl -H "Content-Type: application/json" -X POST "localhost:4000/webhook" -d "{\"object\": \"page\", \"entry\": [{\"messaging\": [{\"message\":\"TEST_MESSAGE\"}]}]}"

use \" because the json parser needs the double quote(" ") for json parsing here we are passing
single quote(' ') that's why the parser failed to parse the json that we are passing

"{\"object\": \"page\", \"entry\": [{\"messaging\": [{\"message\":\"TEST_MESSAGE\"}]}]}"

check this out this will work.

Thanks

Facebook messenger bot error Unexpected token ' in JSON at position 0

2 Answers2

Linked