Slack API invalid_block

user_1287962 0
Viewed 12180

I'm building a simple slack bot and I am playing with the checkboxes element.

When I return the following from my API in a JSON response to a slash-command I get an error failed with the error "invalid_blocks", however, when I put this in the block-kit-builder it works perfectly (including "sending to slack" button)

Any ideas why this is failing when I run my slash command - and is it possible to see more detailed error messages from slack?

{
  "blocks": [
    {
      "elements": [
        {
          "style": "primary",
          "text": {
            "emoji": true,
            "text": "Create new TODO list",
            "type": "plain_text"
          },
          "type": "button",
          "value": "value"
        },
        {
          "style": "primary",
          "text": {
            "emoji": true,
            "text": "Help",
            "type": "plain_text"
          },
          "type": "button",
          "value": "value"
        }
      ],
      "type": "actions"
    },
    {
      "text": {
        "text": "Today",
        "type": "mrkdwn"
      },
      "type": "section"
    },
    {
      "elements": [
        {
          "initial_options": [
            {
              "text": {
                "text": "Get Into the garden",
                "type": "mrkdwn"
              },
              "value": "foo"
            }
          ],
          "options": [
            {
              "text": {
                "text": "Get Into the garden",
                "type": "mrkdwn"
              },
              "value": "foo"
            }
          ],
          "type": "checkboxes"
        },
        {
          "style": "primary",
          "text": {
            "emoji": true,
            "text": "Add new Task",
            "type": "plain_text"
          },
          "type": "button",
          "value": "value"
        }
      ],
      "type": "actions"
    }
  ],
  "type": "home"
}
slack-api
5 Answers

I am using the Slack Web API. I was getting the similar error. After a lot of looking around, here's how I solved it.

import json


blocks = [{...}]

payload = {
    "blocks": json.dumps(blocks)
}

You will then send this payload.

user_26504270

In the Block Kit Builder, the data is a JSON with a blocks key. In the Slack API, the blocks param is only the list of JSON objects.

blocks = [
    {
        "text": {
            "text": "Its the list of your blocks",
            "type": "mrkdwn"
        },
        "type": "section"
    }
]
text = 'Alternative data in text'
client.chat_postMessage(channel=channel_id, blocks=blocks, text=text)
user_166458540

Another cause of this problem seems to be too many blocks being returned. I can't find any documentation about this whatsoever, but personal experience seems to indicate about 20 blocks is the maximum.

An alternative is to return fewer blocks, with paging actions -- paging works well with the "replace" message so that the content being paged through does not result in many separate messages.

user_4301280
user_44050290

It appears that not all valid elements in block kit tool can be posted as a message, despite the fact that message preview works fine in the Block Tool.

In my case, the code failed when I included an input block and passed when i removed it. The input block was generated by the Block Kit tool.

        {
            "type": "input",
            "element": {
                "type": "plain_text_input",
                "action_id": "plain_text_input-action"
            },
            "label": {
                "type": "plain_text",
                "text": "Feedback",
                "emoji": true
            }
        }

The error was {'ok': False, 'error': 'invalid_blocks'}

Also, although the documentation for python says you need to urlEncode the JSON-based array, there is no example, and it is incorrect. https://api.slack.com/methods/chat.postMessage

You can see on line 29 in the SDK test code below that blocks= takes a regular list of dicts not a string. https://github.com/slackapi/python-slack-sdk/blob/c9dc6aa0907a72c16cf36aa15e7e80031a9fdce2/integration_tests/samples/basic_usage/sending_a_message.py

user_11618100
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