i want to make Whatsapp bot and integrated to my website. the system send the qr and users scan it through my website and after users scan and connected i want to send a message to the users it had been connected in the same page. but i got this error
UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
app.get("/create", (req, res) => {
if (req.query["session"] != undefined && req.query["session"] != "") {
venom.create(
`${req.query['session']}`,
(base64Qr, asciiQR, attempts, urlCode) => {
res.send(`<img src="${base64Qr}"></img>`)
},
(statusSession, session) => {
console.log("Status Session: ", statusSession);
},
{ logQR: false, disableWelcome: true
}).then(() => {
res.write("Connected!");
res.end();
})
} else {
res.json({ status: "Error", messages: "Wrong Parameters" });
}
});
res.send() can only be called once. You cannot call this function 2 or more times for a single request.
I am trying to send back a status of 404 to the web client when a request for a non existent record is received.
I'm using Express and MongoDB. Tested with Advanced Rest Client.
Code:
app.get('/api/courses/:id', (req, res) =>
{
dbo.collection("courses").findOne({ id: parseInt(req.params.id) }, function(err, result) {
console.log(result);
if (err) return res.status(400).send(err);
if (!result) { console.log('Null result sending 404'); return res.status(404); }
res.send(result);
});
});
If the client sends a valid id: then the record is returned as expected.
Node Console:
{ _id: 5d23e6a8c922d263376442c1, id: 1, name: 'Course 1' }
Client:
{
"_id": "5d23e6a8c922d263376442c1",
"id": 1,
"name": "Course 1"
}
When the client sends an invalid id: the console shows the message has been sent but the client waits for ever until I stop/reset the server.
Node Console:
null
Null result sending 404
Because you just set status for the response, but you never send back to client anything.
Let's send something to the client.
Example, send a json object
return res.status(404).json({message: 'Null result sending 404'});
instead of return res.status(404);
how to display Commands results in IoT Central - Commands page?
Flow:
Command sent to Device
Device received the command and returns Payload:
{
"status": 200,
"payload": {
"command": "ping",
"result_code": "ok",
"result_data": "ping 5 ms"
}
}
How to display this data in IoT Central?
Now IoT Central shows only default "Sent at ..." message.
If you set a reported property with the same name as the command when you handle the command on the device, then you can set a value that displays in the IoT Central UI. For example, using Node.js you can create a handler for a countdown method like this:
function onCountdown(request, response) {
console.log('received a request for Countdown');
console.log(JSON.stringify(request.payload, null, 2));
var fakeResponsePayload = {
key: 'value'
};
response.send(200, fakeResponsePayload, function (err) {
if (err) {
console.error('Unable to send method response: ' + err.toString());
} else {
console.log('response to Countdown sent.');
client.getTwin(function(err, twin) {
if (err) {
console.error('could not get twin');
} else {
console.log('twin created');
var patch = {
countdown:{
value: 18
}
};
twin.properties.reported.update(patch, function(err) {
if (err) {
console.error('unable to update twin: ' + err.toString());
} else {
console.log('twin state reported');
}
});
}
});
}
});
}
client.onDeviceMethod('countdown', onCountdown);
Note that the name of the field name of the command is countdown.
There is also a C++ example here: https://github.com/Azure/iot-central-firmware/blob/master/MXCHIP/mxchip_advanced/src/registeredMethodHandlers.cpp
I'm playing around with building a simple Facebook Messenger chatbot and I'm having trouble sending messages in sequence.
In the example above, it should have printed "Hello!", "1", "2", "3" in order. I'm currently following the Facebook docs found here to implement this simple text message function. I've included my Express Node.JS server code below:
Defining the sendTextMessage() function:
var request = require("request");
function sendTextMessage(user, text) {
messageData = {
text: text
};
request({
url: "https://graph.facebook.com/v2.6/me/messages",
qs: {access_token: PAGE_ACCESS_TOKEN},
method: "POST",
json: {
recipient: {id: user},
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);
} else {
console.log("Message successfully send.")
}
});
}
Using it to send a response:
sendTextMessage(user, "Hello!");
sendTextMessage(user, "1");
sendTextMessage(user, "2");
sendTextMessage(user, "3");
I even tried implementing a simple queue that queues messages and only sends one message at a time after each request's success callback. This is making me suspect that I'm not interacting with the Messenger API correctly.
Has anyone encountered this issue? How can I get messages to send in sequence? Thanks!
EDIT
Because I implemented a simple queue but still experiencing this problem, I'm including the code for my simple queue system here.
var queue = [];
var queueProcessing = false;
function queueRequest(request) {
queue.push(request);
if (queueProcessing) {
return;
}
queueProcessing = true;
processQueue();
}
function processQueue() {
if (queue.length == 0) {
queueProcessing = false;
return;
}
var currentRequest = queue.shift();
request(currentRequest, function(error, response, body) {
if (error || response.body.error) {
console.log("Error sending messages!");
}
processQueue();
});
}
queueRequest(/* Message 1 */);
queueRequest(/* Message 2 */);
queueRequest(/* Message 3 */);
UPDATE
This "bug" was reported to Facebook but it sounds like they aren't going to fix it. Please read the ticket thread on Facebook's post here for details on what they say is going on. (Thank you to Louise for getting Facebook's attention on this)
I submitted a bug report to Facebook about this because I was having the same problem. They acknowledged that it is indeed a bug and are working to fix it: https://developers.facebook.com/bugs/565416400306038
After you send a POST to /me/messages, you'll receive a response that has a message id (mine start with 'mid.' which maybe stands for message id?):
{ recipient_id: '1015411228555555',
message_id: 'mid.1464375085492:b9606c00ca33c12345' }
After being completely received by the FB Messenger API, you'll get a call to your webhook (with no message events) that confirms receipt:
{ sender: { id: '1015411228555555' },
recipient: { id: '566031806XXXXXX' },
delivery:
{ mids: [ 'mid.1464375085492:b9606c00ca33c12345' ],
watermark: 1464375085604,
seq: 176 } }
I think that delivery receipt is the best way to ensure delivery, then send the next message.
Implement the send request as a Promise and only send consequent messages once the previous one is resolved
const send = (userId, messageData) => {
return new Promise((resolve, reject) => {
request
(
{
url : BASE_URL + "me/messages",
qs : { access_token : PAGE_ACCESS_TOKEN },
method : "POST",
json :
{
recipient: { id : userId },
message: messageData,
}
}, (error, response, body) =>
{
if (error) { console.log("Error sending message: " + response.error); return reject(response.error); }
else if (response.body.error) { console.log('Response body Error: ' + response.body.error); return reject(response.body.error); }
console.log("Message sent successfully to " + userId);
return resolve(response);
}
);
});
};
You can achieve QUEUING by promises.
function delay(time) {
return new Promise(function(resolve, reject) {
setTimeout(resolve, time);
});
}
delay(2000).then(() => {
console.log('hi');
delay(2000).then(() => {
console.log('hello');
delay(2000).then(() => {
console.log('welcome');
})
})
})
Instead of adding static timeouts, I would create a queue data structure. When the bot wants to send a message, append the contents to the end of the queue. On the message post callback, check if there are any messages still in the queue and call the function again using recursion and remove from the queue accordingly.
They should be received in the order that they are sent. Make sure you're actually sending them in order and not calling an async function 4 times (and send order isn't guaranteed). (I read that you tested it but in all my testing I've never seen a receive come out of order if the send order was guaranteed.)
I added a messageId counter to the app that resets to 0 on every start of messagehandling. Then I delay with that number * 100 ms. This way I can add intentional delays as well with code like messageDelay += 15
receivedMessage(event) {
messageDelay = 0;
//...
sendMessage extend:
function sendTextMessage(recipientId, messageText) {
//...
setTimeout(function() {
callSendAPI(messageData);
}, messageDelay++ * 100)
}
The message is not sending in order because, the request is sent asynchronously to facebook, and can be sent in any order.
To solve this you have to call the next sendTextMessage when the message that should be sent before it has received a response.
Based on the recursive solution proposed by #user3884594, I kind of make it work using this (I removed the error handling in order to simplify):
send_messages (["message 01", "message 02", "message 03"]);
function send_messages (which, i = 0)
{
request({
url: 'https://graph.facebook.com/v2.10/me/messages',
qs: { access_token: FACEBOOK_ACCESS_TOKEN },
method: 'POST',
json: { recipient: { id: senderId }, message: { text: which [i] }
}, (error, response, body) =>
{
// You need to put your error handling logic here
if (i++ < which.length - 1)
send_messages (which, i);
});
}
I had exactly same problem, that solution worked for me:
function sendMessage(recipient, messages, accessToken, i) {
axios.post(baseURL + 'v2.11/me/messages/?access_token=' + accessToken,
Object.assign({}, {
messaging_type: "RESPONSE",
recipient: {
id: recipient
}
}, messages[i]['payload']) )
.then(response => {
if(i < messages.length) sendMessage( recipient, messages, accessToken, i+1 );
},
error => {})
.catch(error => {});
}
sendMessage(recipient, flow['messages'], flow['page']['accessToken'], 0);
That's my question: Sequential Message Sending Using Facebook Send-API
You can try putting them inside a setTimeout function so each one goes after a certain period of time.
So replace this:
sendTextMessage(user, "Hello!");
sendTextMessage(user, "1");
sendTextMessage(user, "2");
sendTextMessage(user, "3");
With this:
sendTextMessage(user, "Hello!");
// 1 second
setTimeout(function() {
sendTextMessage(user, "1");
}, 1000)
// 2 seconds
setTimeout(function() {
sendTextMessage(user, "2");
}, 2000)
// 3 seconds
setTimeout(function() {
sendTextMessage(user, "3");
}, 3000)
And they should go one after another. You could also embed the functions inside each other if need be.
I've got the following code that can send push notifications using Azure Notification Hubs. When a new item is inserted into the database, this code sends a push notification to the devices registered with the tag.
I'm using Ionic/Phonegap for the iOS app and the ngCordova Push Plugin. I want to add badge counts for iOS devices, but I can't seem to find a way to do this. I've tried using the push.apns.send function, but can't get it to work.
Azure Mobile Services
function insert(item, user, request) {
// Execute the request and send notifications.
request.execute({
success: function() {
// Create a template-based payload.
var payload = '{ "message" : "This is my message" }';
push.send("My Tag", payload, {
success: function(pushResponse){
// Send the default response.
request.respond();
},
error: function (pushResponse) {
console.log("Error Sending push:", pushResponse);
// Send the an error response.
request.respond(500, { error: pushResponse });
}
});
}
});
}
Phonegap
var iosConfig = {
"badge": true,
"sound": true,
"alert": true
};
$cordovaPush.register(iosConfig).then(function (deviceToken) {
var hub = new NotificationHub(mobileClient);
// This is a template registration.
var template = "{\"aps\":{\"alert\":\"$(message)\"}}";
// Register for notifications.
// (deviceId, ["tag1","tag2"], templateName, templateBody, expiration)
hub.apns.register(deviceToken, myTags, "myTemplate", template, null).done(function () {
// Registered with hub!
}).fail(function (error) {
alert("Failed registering with hub: " + error);
});
}, function (err) {
alert("Registration error: " + err)
});
I've searched through dozens of articles/tutorials and none of them work. Any help would be greatly appreciated.
I finally figured it out. The issue was that the template registration needed to include the badge. Here's what works:
Azure Mobile Services
function insert(item, user, request) {
// Execute the request and send notifications.
request.execute({
success: function() {
// Create a template-based payload.
var payload = '{ "message" : "' + originalMessage + '", "badge" : "100" }';
push.send("My Tag", payload, {
success: function(pushResponse){
// Send the default response.
request.respond();
},
error: function (pushResponse) {
console.log("Error Sending push:", pushResponse);
// Send the an error response.
request.respond(500, { error: pushResponse });
}
});
}
});
}
Phonegap
var iosConfig = {
"badge": true,
"sound": true,
"alert": true
};
$cordovaPush.register(iosConfig).then(function (deviceToken) {
var hub = new NotificationHub(mobileClient);
// This is a template registration.
var template = "{\"aps\":{\"alert\":\"$(message)\",\"badge\":\"#(badge)\" }}";
// Register for notifications.
// (deviceId, ["tag1","tag2"], templateName, templateBody, expiration)
hub.apns.register(deviceToken, myTags, "myTemplate", template, null).done(function () {
// Registered with hub!
}).fail(function (error) {
alert("Failed registering with hub: " + error);
});
}, function (err) {
alert("Registration error: " + err)
});