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Hackernoon logoHow To Create a ChatBot on Facebook Messenger Using Flask and Heroku by@pmgmt

How To Create a ChatBot on Facebook Messenger Using Flask and Heroku

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@pmgmtIhor Udod

Project Facilitator at EL Passion, Warsaw

Basic Facebook bot (will chat with you using random phrases you set up) using Flask and Python. You can start with this bot as a basic app to build something more difficult and useful.

What do you need to run this bot?

  1. Sublime Text + Terminal
  2. Clone this repo: https://github.com/udodihor/flask-fb-bot
  3. Heroku free account and Heroku CLI
  4. Facebook account (to use Facebook Developer Center)
  5. 30 min of your timeBot app

You can just clone a source code from this repo. Only few things you will need to change (Token Variables). After copying current code, go to your Terminal, open the project folder and run the following command:

$ pip install -r requirements.txt

So now, you can run a flask app using terminal (in project folder):

$ python app.py

If all goes well, you might see a URL to the Flask App. To test it, copy and paste this link to the browser or just type: http://localhost:5000

You will see an error: Invalid verification token.

1. Set up a Facebook Application

1.1. Create app

Go to: https://developers.facebook.com/apps Create a new application with a random name. Next, when prompted on the next page for the type of product you are building, click the “Set Up” button on the Messenger option.

1.2. Generate Access token

After you were redirected on the Settings page, you need to select or create a specific Facebook Page (Public community or other) to assign to your bot.

Now, you need to Generate Token for your app and actually paste this FB token to your application in 

app.py
 find 
ACCESS_TOKEN = 'GENERATED_TOKEN_FROM_FACEBOOK'
 and change value with your generated token.

1.3. Create Verify Token

Next, in the 

VERIFY_TOKEN
 value put any variable you want. To protect your bot, Facebook requires you to have a verify token. When a user messages your bot, Facebook will send your bot the message along with this verify token for your Flask app to check and verify the message is an authentic request sent by Facebook. Choose a string you want to use for your verify token and replace the placeholder in the app.py file with your code (ex. “
TESTINGTOKEN
” could be your verify token, but I’d recommend something harder for someone to guess) and place the same token (minus the quotation marks) in the Verify Token field.

2. Create a Heroku account

Register on Heroku. It's free.

3. Setup Heroku CLI

Go to your terminal, and paste following command:

$ brew tap heroku/brew && brew install heroku

or download and install automatically here.

After Heroku CLI is successfully installed, we could create our first heroku application! 👏

4. Heroku app creation

In your terminal, run next command:

$ heroku login 

and push any button.

You'll be redirected to default browser app and asked for login to your heroku account. After successful login, go back to your terminal window. Now you're logged in. To create new app, run command:

$ heroku create

If all goes well, you will see something similar to: 

Heroku will automatically create a new application instance in your account. After creation, you will see a git URL to your heroku app (we will deploy our bot there).

Finally, to deploy the app, paste next command in your terminal:

$ git push heroku master

⚠️ NOTE: If you cloned this repo, it will work fine. If you just downloaded the files from GitHub, you will need to initiate git repo, and create first commit and only then start to push your code to heroku:

$ git init.
$ git add -A && git commint -m "First commit"

After that, copy the URL of your heroku web-app you previously created. You can check it in your heroku account (go into the created application, and find an "Open" button).

5. Set up Webhook

In Facebook Developer Center, in your Messenger settings, add a Callback URL to Webhooks section: 

Here, you will need to paste URL to your heroku app (we copied it in previous step), and into another field put the value (

VERIFY_TOKEN = YOUR_CREATED_VALUE
) you've created in step 1.3.

If you've did all right, Facebook will test this callback and add this to the app. After that, for the subscription fields, be sure to check the

messages
,
messaging_postbacks
,
message_deliveries
,
messaging_pre_checkouts
boxes: 

So, it was a final step. Go to your messages in Facebook, create a new message and send it to previously created community/group.

Enjoy & Thank you! 👏 🙌

Alternative deployment, using ngrok is here

Feel free to ask me here or on reddit

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