Hey team,

TLDR; I want my Zapier to perform an action in Slack that isn’t possible with the out-of-the-box Zapier/Slack scopes. How can I achieve this?

As part of my Zapier flow, I want to add a emoji reaction to a message. This isn’t provided by the Slack application, so I create a Custom Action. No problems. Here’s the code it’s generated as my custom action:

export async function addEmojiReactionToSlackMessage({
  channelId,
  messageTimestamp,
  emojiName,
}: {
  channelId: string;
  messageTimestamp: string;
  emojiName: string;
}): Promise<{ result: boolean }> {
  // Define the API endpoint URL
  const url = 'https://slack.com/api/reactions.add';

  // Prepare the request body with the required parameters
  const requestBody = {
    channel: channelId,
    name: emojiName, // The emoji reaction to add, provided as input
    timestamp: messageTimestamp,
  };

  // Make the API request using fetchWithZapier
  const response = await fetchWithZapier(url, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify(requestBody),
  });

  // Throw an error if the response is not ok
  await response.throwErrorIfNotOk();

  // Parse the JSON response
  const data = await response.json();

  // Return the result indicating success
  return { result: data.ok };
}

When I run the action, I get the following error (emphasis added): 

kemit:log] {"message":"Relay Response","data":{"status":200,"requestId":"4f7fd502-48b5-4a9f-a4fa-72b4afa81efa","text":"{\"ok\":false,\"error\":\"missing_scope\",\"needed\":\"reactions:write\",\"provided\":\"identify,channels:history,groups:history,channels:read,emoji:read,files:read,groups:read,im:read,mpim:read,reactions:read,search:read,stars:read,team:read,users:read,users:read.ema"}}

"emit:data] {"result":false}

exit code: 0

The Zapier app by default doesn’t request the reactions:write scope when installed into Slack, so the error is understandable.

I have looked at and discarded the following options:

Extending the scopes requested by Zapier app on install into Slack

I can’t see how this is even possible. The scopes appear to be fixed. Have I missed something?

Using a separate Slack App and tokens with the right scope

I created a new Slack App with the reactions:write scope and generated OAuth tokens.

1. It doesn’t appear to be possible to use this in place of the OAuth approval flow in the Zapier Editor
2. I tried using the OAuth token in the Custom Action as a Bearer token as discussed here, but no joy. Get the following error

lemit:log] {"message":"Relay Response","data":{"status":200,"requestId":"5c8b8abd-b05c-4df6-afb3-298ce6ac0692","text":"{\"ok\":false,\"error\":\"invalid_auth\",\"warning\":\"missing_charset\",\"response_metadata\":{\"warnings\":t\"missing_charset\"]}}"}}

eemit:data] {"result":false}

Any suggestions for how to achieve the above?