"Payload" option on Facebook Bots buttons

Question

Facebook Send API mentions a "payload" type you can set for buttons on the Generic Response Template. However, they don't say how it works, other than:

For postback buttons, this data will be sent back to you via webhook

But how is it sent back? I don't receive any messages when I click the payload button. Has anyone successfully used it?

Bookerbookie

did you subscribed to messaging_postbacks option while setting up web-hook for messenger bot..? developers.facebook.com/docs/messenger-platform/… – Sisyphus

Answer 1

I tested it and it works for me. The payload of a button acts like the value on a html button. This means it's not visible to the user but it's the value that's send back to you.

If you create a button like that:

'attachment': {
    'type': 'template',
    'payload': {
        'template_type': 'button',
        'text': 'This is the description',
        'buttons': [
             {
                 'type': 'postback',
                 'title': 'This is the visible text',
                 'payload': 'This is the value you get back'
             }
        ]
 }

A callback including a payload looks like that:

{'timestamp': 1461697120850, 'postback': {'payload': 'this is the value you get back'}, 'recipient': {'id': xxxxxxxx}, 'sender': {'id': xxxxxxxx}}

Kornegay

how to capture it's value in php ? – Amish

@Amish if(isset($input['entry'][0]['messaging'][0]['message']['quick_reply'])){ $payload_txt = $input['entry'][0]['messaging'][0]['message']['quick_reply']['payload']; – Fairlead

Have you test these lines ? I tried it it's not working – Backpack

During debugging I log all requests received into a textfile: file_put_contents("testfile.txt", json_encode( $input ) . PHP_EOL, FILE_APPEND | LOCK_EX); – Seven

Good for viewing request structure – Seven

Is anyone able to see docs on the maximum allowed size of the payload. Can't find it here – Edana

how can i add custom keys to the default button array 'attachment': { 'type': 'template', 'payload': { 'template_type': 'button', 'text': 'This is the description', 'buttons': [ { 'type': 'postback', 'title': 'This is the visible text', 'payload': 'This is the value you get back' 'custom_field': number } ] } – Oppression

Answer 2

When you click the Button a POST message is sent to your /webhook.

You have to handle the payload like this:

app.post('/webhook/', function (req, res) {
  messaging_events = req.body.entry[0].messaging;
  for (i = 0; i < messaging_events.length; i++) {
    event = req.body.entry[0].messaging[i];
    sender = event.sender.id;
    if (event.message && event.message.text) {
      text = event.message.text;
      // Handle a text message from this sender
    } else if (event.postback && event.postback.payload) {
      payload = event.postback.payload;
      // Handle a payload from this sender
    }
  }
  res.sendStatus(200);
});

This code snippet is from the Getting Started Guide from Facebook except for the else if where you can react on the payload.

Shiver

hi, how can we implement with php, unable to find perfect way to get the value of payload – Amish

Answer 3

This is how you read back the payload:

$payload = $input['entry'][0]['messaging'][0]['postback']['payload'];

Indistinct