Facebook webhook making multiple calls for the same message?

Question

I made and echo bot on AWS with Python and serverless.

I keep getting the same request again and again. I read the faq where it says u have to deliver a status code 200 else it will keep retrying the webhook.

I'm not sure How I do this.

I have noticed that the sequence number is always the same for the calls so I assume the reply I sent was not acknowledged. my code is here

import os
import json
import requests
import random
from datetime import datetime
######################
# helper functions
######################
##recursively look/return for an item in dict given key
def find_item(obj, key):
    item = None
    if key in obj: return obj[key]
    for k, v in obj.items():
        if isinstance(v,dict):
            item = find_item(v, key)
            if item is not None:
                return item

##recursivley check for items in a dict given key
def keys_exist(obj, keys):
    for key in keys:
        if find_item(obj, key) is None:
            return(False)
    return(True)

##send txt via messenger to id
def send_message(send_id, msg_txt):
    print("Send message called")
    print (datetime.utcnow().strftime('%Y-%m-%d %H:%M:%S.%f')[:-3])
    params  = {"statusCode": 200,"access_token": os.environment['accesstoken']}
    headers = {"statusCode": "200","Content-Type": "application/json"}
    data = json.dumps({"statusCode": "200","recipient": {"id": send_id},
                       "message": {"text": msg_txt}})

    r = requests.post("https://graph.facebook.com/v2.9/me/messages", params=params, headers=headers, data=data)
    print (r.text)

    if r.status_code != 200:
        print(r.status_code)
        print(r.text)



#-----------------------------------------------------------

def hello(event, context):
    #debug
    event=json.loads(json.dumps(event))
    print("event:" )
    print(event)
    # print("context")
    # print(context)


    #handle webhook challenge
    try:

        if keys_exist(event, ["queryStringParameters","hub.verify_token","hub.challenge"]):
            print("subscribe to webhook invoked")
            v_token   = str(find_item(event, 'hub.verify_token'))
            challenge = find_item(event, 'hub.challenge')
            if ("strongtoken" == v_token):
                response = {
                    "statusCode": 200,
                    "body": str(challenge)
                }
                print(challenge)
                return response

        #handle messaging events
        if keys_exist(event, ['body']):
            event_entry=json.loads(event['body'])
            if ((len(event_entry['entry'])>0) & (keys_exist(event_entry['entry'][0],['messaging'])) ):
                messaging_event = event_entry['entry'][0]['messaging'][0]
                if (keys_exist(messaging_event,['message'])):
                    msg_txt   = messaging_event['message']['text']
                    sender_id = messaging_event['sender']['id']
                    print(sender_id)
                    first_word = msg_txt.split(" ")[0]
                    send_message(sender_id, msg_txt)
                else:
                    print("Did not send message")
                    pass
            else:
                print("Did not send message")
                pass

        else:
            pass
    except:
        pass

I have given the status code 200 in soo many places and I'm not sure y I still keep getting the same problem.

Answer 1

If you are getting multiple messages your server did not return 200 status code to webhook request from Facebook server. This means an error occurred on your part otherwise 200 should be returned. It looks to me that problems are in following lines:

params  = {"statusCode": 200,"access_token": os.environment['accesstoken']}
headers = {"statusCode": "200","Content-Type": "application/json"}
data = json.dumps({"statusCode": "200","recipient": {"id": send_id},
                   "message": {"text": msg_txt}})

Firstly you are passing statusCode in a data body of message and according to this documentation message response should not contain it.

Another problem could be sending status code inside params. I would remove status code completely from send_message method. I doubt its needed there. You are basically trying to return status 200 on wrong end. You are trying to return it on output instead of input (from Facebooks point of view).

So its quite possible you are correctly getting message from Facebook but you are still returning wrong status code because you are calling send_message method from inside messaging event and send_message method should return status "400 bad request" because you are sending faulty request. Thus your server also returns wrong response code.

Just make sure your code works correctly and 200 should be returned.

EDIT: So i would try with following code:

params  = {"access_token": os.environment['accesstoken']}
headers = {"Content-Type": "application/json"}
data = json.dumps({"recipient": {"id": send_id},
                   "message": {"text": msg_txt}})

Answer 2

I'm working on a Facebook Messenger chatbot with a Node/Express server and was having the same exact issue. The server was appropriately sending 200 responses and yet the issue persisted. I resolved the problem by caching message ID's and checking for duplicates before processing:

var NodeCache = require('node-cache');
var myCache = new NodeCache();

app.post('/webhook/', function(req, res) {
    var messageID = req.body.entry[0].messaging[0].message.mid;
    var checkForDupe = myCache.get(messageID);

    if (checkForDupe == undefined) {
        var setID = myCache.set(req.body.entry[0].messaging[0].message.mid, req.body.entry[0].messaging[0].message.mid);
        //Handle message .....

I hope this helps someone. It was driving me nuts.