How To Build A Chatbot - Part 1 🔥

Learn to build a facebook chatbot using Python and Flask

Part 2

Table of Contents

• Create Facebook Page
• Installation
  • Download Project
  • Install Dependencies
• Server
  • Flask
  • ngrok
• Code for the bot
  • Verify Method
  • Webhook Method
  • Send Message Method

Create a Facebook Page

After you've created a page, click on this Link to create a Facebook App to access FB's developer's console.

Stuff to install and setup

Prereq: Make sure you have python installed on your laptop

Download Project Files

You can download the files here

Install Dependencies

Navigate into the downloaded folder using cd and once you reach the root folder run the following command in your terminal.

pip install -r requirements.txt

Setting up your first flask server

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

if __name__ == "__main__":
    app.run()

Run the following command, python hello_world.py

Open localhost:5000 in your browser. And you'll see "Hello World"

Now, go to your root folder and run the command below.

./ngrok http 5000

Now, the whole world can see "Hello World" if they use the link ;)

Code Breakdown

verify() method

This method is used only once. It's for Facebook to check if the link you've given it is valid or not.

@app.route('/', methods=['GET'])
def verify():

    if request.args.get("hub.mode") == "subscribe" and request.args.get("hub.challenge"):
        if not request.args.get("hub.verify_token") == "test_token":
            return "Verification token mismatch", 403
        return request.args["hub.challenge"], 200

    return "Hello world", 200

webhook() method

This is the main method that recieves user's messages.

@app.route('/', methods=['POST'])
def webhook():

    # Recieve your package from facebook

    data = request.get_json()
    
    # print(data)
    
    if data["object"] == "page":

        for entry in data["entry"]:
            for messaging_event in entry["messaging"]:

                if messaging_event.get("message"):  # someone sent us a message

                    sender_id = messaging_event["sender"]["id"]        # the facebook ID of the person sending you the message
                    recipient_id = messaging_event["recipient"]["id"]  # the recipient's ID, which should be your page's facebook ID
                    message_text = messaging_event["message"]["text"]  # the message's text

                    print(sender_id)
                    print(message_text)

                    # responding to your user
                    send_message(sender_id, message_text)

                if messaging_event.get("delivery"):  # delivery confirmation
                    pass

                if messaging_event.get("optin"):  # optin confirmation
                    pass

                if messaging_event.get("postback"):  # user clicked/tapped "postback" button in earlier message
                    pass

    return "ok", 200

send_message() method

This is the method that sends messages back to Facebook.

def send_message(recipient_id, message_text):

    # Prepare your package

    params = {
        "access_token": "ADD_YOUR_PAGE_ACCESS_TOKEN"
    }
    headers = {
        "Content-Type": "application/json"
    }
    data = json.dumps({
        "recipient": {
            "id": recipient_id
        },
        "message": {
        	# add the text you want to send here
            "text": message_text
        }
    })

    # Send the package to facebook with the help of a POST request
    r = requests.post("https://graph.facebook.com/v2.6/me/messages", params=params, headers=headers, data=data)

    # do this to check for errors
    if r.status_code != 200:
    	print("something went wrong")

Useful References

Here's another tutorial
Flask Documentation
read more abour ngrok
Read about get and most requests