How to use facebook messenger send image API in Node js? - node.js

Question

I'm building a facebook bot in nodejs with facebook messenger API. I'm trying to send a image from the bot by directly uploading the image file from the heroku server itself (not through URL) and it does not work.
Here is a error log from the console.
Failed calling Send API 400 Bad Request { message: '(#100) Incorrect
number of files uploaded. Must upload exactly one file.',type:
'OAuthException', code: 100,error_subcode: 2018005,fbtrace_id:
'E32ogm/ofxd' }
The official facebook document only contains an example in curl format and I'dont know how to replicate this curl into node format.
I've tested with curl and it worked like a charm.
curl \ -F 'recipient={"id":"recipientId"}' \ -F 'message={"attachment":{"type":"image", "payload":{}}}' \ -F 'filedata=#resource/pdf_img/sample.jpg;type=image/jpeg' \ "https://graph.facebook.com/v2.6/me/messages?access_token=PAGE_ACCESS_TOKEN"
This is my node implementation that seems to be problematic,
//file_loc = __dirname+"/resource/pdf_img/sample.jpg"
function sendImageMessage(recipientId, file_loc){
let fs = require('fs');
var readStream = fs.createReadStream(file_loc);
var messageData = {
recipient : {
id : recipientId
},
message : {
attachment : {
type : "image",
payload :{}
}
},
filedata:readStream
}
callSendAPI(messageData);
}
function callSendAPI(messageData) {
request({
uri: "https://graph.facebook.com/v2.6/me/messages",
qs: {access_token: process.env.PAGE_ACCESS_TOKEN},
method: "POST",
json: messageData
}, function(error, response, body) {
if (!error && response.statusCode == 200) {
var recipientId = body.recipient_id;
var messageId = body.message_id;
if (messageId) {
console.log("Successfully sent message with id %s to recipient %s",
messageId, recipientId);
} else {
console.log("Successfully called Send API for recipient %s",
recipientId);
}
} else {
console.error("Failed calling Send API", response.statusCode, response.statusMessage, body.error);
}
});
}
Please any help with fixing my node implementation or translating that curl in to node would be appreciated.

Answer 1

You can use forms /form-data/ in the request module (which has integrated module 'form-data').
But all requests needs to be stringified.
So, based on your example, the following should do the job >>
function sendImageMessage(recipientId, file_loc){
let fs = require('fs');
var readStream = fs.createReadStream(file_loc);
var messageData = {
recipient : {
id : recipientId
},
message : {
attachment : {
type : "image",
payload :{}
}
},
filedata:readStream
}
callSendAPI(messageData);
}
function callSendAPI(messageData) {
var endpoint = "https://graph.facebook.com/v2.6/me/messages?access_token=" + process.env.PAGE_ACCESS_TOKEN;
var r = request.post(endpoint, function(err, httpResponse, body) {
if (err) {return console.error("upload failed >> \n", err)};
console.log("upload successfull >> \n", body); //facebook always return 'ok' message, so you need to read error in 'body.error' if any
});
var form = r.form();
form.append('recipient', JSON.stringify(messageData.recipient));
form.append('message', JSON.stringify(messageData.message));
form.append('filedata', messageData.filedata); //no need to stringify!
}
Details here https://github.com/request/request#forms

Answer 2

I think sending variable messagedata as formdata would solve the problem.
var FormData = require('form-data');
var fs = require('fs');
var https = require('https');
function sendImageMessage(recipientId, file_loc){
var readStream = fs.createReadStream(file_loc);
var messageData = new FormData();
messageData.append('recipient', '{id:' +recipientId+ '}');
messageData.append('message', '{attachment :{type:"image", payload:{}}}');
messageData.append('filedata', readStream);
callSendAPI(messageData);
}
Secondly you need to change request a bit since now you are using formdata. I have done it using module https and so have changed the callSendAPI() code accordingly. You can find out how to send the formdata using request module.
function callSendAPI(messageData) {
var options = {
method: 'post',
host: 'graph.facebook.com',
path: '/v2.6/me/messages?access_token=' + pagetoken,
headers: messageData.getHeaders()
};
var request = https.request(options);
messageData.pipe(request);
request.on('error', function(error) {
console.log("Unable to send message to recipient %s", recipientId);
return;
});
request.on('response', function(res) {
if (res.statusMessage == "OK") {
console.log("Successfully sent message to recipient %s", recipientId);
} else {
console.log("Unable to send message to recipient %s", recipientId);
}
return;
});
}