Submitting modal from views_open() always fails

Description

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What type of issue is this? (place an x in one of the [ ])

• bug
• enhancement (feature request)
• question
• documentation related
• testing related
• discussion

Requirements (place an x in each of the [ ])

• I’ve read and understood the Contributing guidelines and have done my best effort to follow them.
• I’ve read and agree to the Code of Conduct.
• I’ve searched for any related issues and avoided creating a duplicate issue.

---

Bug Report

Hey- I’m using the python-slackclient v2.7.2 in my Flask app to open a modal and get user input. I followed this guide https://python-slackclient.readthedocs.io/en/latest/basic_usage.html under the section ‘Opening a modal’. I followed the exact steps there, but always get the error ‘We had some trouble connecting. Try again?’ when I try to submit the modal. I’ve been searching for a solution, but the example seems right- it IS returning a 200 response with an empty body on success. I’ve tried a bunch of other examples as well, but the form won’t submit even though the proper response is being sent in less than 3 seconds

Reproducible in:

slackclient version: 2.7.2

python version: 3.8.2

OS version(s): OSX catalina 10.15.4

Steps to reproduce:

1. Add the following to an app.py file:

from flask import Flask, request, make_response, Response
from slack import WebClient
from slack.errors import SlackApiError
from slack.signature import SignatureVerifier

import os
import json


# Your app's Slack bot user token
SLACK_BOT_TOKEN = os.environ["SLACK_BOT_TOKEN"]
SLACK_VERIFICATION_TOKEN = os.environ["SLACK_VERIFICATION_TOKEN"]

# Slack client for Web API requests
client = WebClient(SLACK_BOT_TOKEN)

# Flask web server for incoming traffic from Slack
app = Flask(__name__)
signature_verifier = SignatureVerifier(os.environ["SLACK_SIGNING_SECRET"])

@app.route("/", methods=["POST"])
def slack_app():
  if not signature_verifier.is_valid_request(request.get_data(), request.headers):
    return make_response("invalid request", 403)

  if "command" in request.form \
    and request.form["command"] == "/open-modal":
    trigger_id = request.form["trigger_id"]
    try:
      response = client.views_open(
        trigger_id=trigger_id,
        view={
          "type": "modal",
          "callback_id": "modal-id",
          "title": {
            "type": "plain_text",
            "text": "Awesome Modal"
          },
          "submit": {
            "type": "plain_text",
            "text": "Submit"
          },
          "close": {
            "type": "plain_text",
            "text": "Cancel"
          },
          "blocks": [
            {
              "type": "input",
              "block_id": "b-id",
              "label": {
                "type": "plain_text",
                "text": "Input label",
              },
              "element": {
                "action_id": "a-id",
                "type": "plain_text_input",
              }
            }
          ]
        }
      )
      return make_response("", 200)
    except SlackApiError as e:
      code = e.response["error"]
      return make_response(f"Failed to open a modal due to {code}", 200)

  elif "payload" in request.form:
    payload = json.loads(request.form["payload"])
    if payload["type"] == "view_submission" \
      and payload["view"]["callback_id"] == "modal-id":
      submitted_data = payload["view"]["state"]["values"]
      print(submitted_data)  # {'b-id': {'a-id': {'type': 'plain_text_input', 'value': 'your input'}}}
      return make_response("", 200)

  return make_response("", 404)

if __name__ == "__main__":
  # export SLACK_SIGNING_SECRET=***
  # export SLACK_API_TOKEN=xoxb-***
  # export FLASK_ENV=development
  app.run("localhost", 5000)


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

1. Set your environment variables.
2. Run the app with python3 -m flask run
3. Start ngrok with ngrok http 5000
4. Create a slash command in your slack app called /open-modal and set the endpoint to the ngrok https endpoint from above.
5. Invoke /open-modal in slack, enter input, and click Submit
6. See error

Expected result:

The form submits successfully and POST’s data back to the endpoint…

[arevaloleo]

@seratch I have the right interactivity endpoint setup and the endpoint can receive the modal id. I am using fastapi not flask btw.

@app.post("/interactive")
async def interactive(request: Request):
    form = await request.form()
    body = jsonable_encoder(form['payload'])
    dict_payload = json.loads(body)
    print("received callback_id"+dict_payload.get('view').get('callback_id'))
    return ""

I guess the issue seem to be slackclient won’t close the modal after the submission somehow?

could you solve it?

[seratch]

Hi, thanks for sharing this!

I’m afraid that you haven’t yet set up the Request URL in the Interactivity & Shortcuts section. To receive view submission requests, telling your endpoint URL to the Slack API server beforehand is required. Refer to https://api.slack.com/interactivity/handling#setup for more details.

Also, I will improve this SDK’s document to be more friendly for developers. Thanks a lot 🙇