How to post new message to slack after receive response from interactive button

Question

I feel like I am missing out some parts, but I could not figure out and will require some help here.

I have a slack button to receive user's response and this response will trigger another block message and I intend to send this block as a new message to slack.

However, this ended up returning an empty body to slack.

Is there a way for me to post a new message to slack base on user's response through the interactive button?

This is the function that will send message out to slack

SLACK_URL = "https://slack.com/api/chat.postMessage" # use postMessage if we want visible for everybody, postEphemeral private view
channel_id = channel
user = user
bot_token = os.environ["BOT_TOKEN"]
data = urllib.parse.urlencode({
        "token": bot_token,
        "channel": channel_id,
        "attachments": json.dumps(block),
        "user": user,
        "link_names": True
    })
data = data.encode("ascii")
request = urllib.request.Request(SLACK_URL, data=data, method="POST")
request.add_header( "Content-Type", "application/x-www-form-urlencoded" )
res = urllib.request.urlopen(request).read()
print('res:', res)

This is the response I see from my logs, which return empty to slack

"attachments": [
        {
            "id": 1,
            "fallback": "[no preview available]"
        }

All my block kit code are all from slack block kit builder