How do I generate a custom session id for my Slack Q&A agent using Postgres Memory?

Below is an explanation and a potential workaround since Slack doesn't provide a dedicated session id out-of-the-box:

Why No Session ID from Slack?

The Slack event payload, as received via the Slack Trigger node, doesn't include a dedicated session id. In contrast, when using a normal Chat Trigger node (or similar), n8n attaches a session id that the Postgres Chat Memory node expects. With Slack, you have to work around this limitation.

How to Work Around the Issue

You can generate your own session key based on information available in the Slack message payload—such as the user id and channel id—to use as a session id for storing chat history. For example:

1. Use a Function Node:
   After the Slack Trigger node, you can add a Function node that creates a custom session id. A simple approach is to concatenate the Slack user id and channel id.

   JAVASCRIPTCopied
   // Access user id and channel id from the incoming JSON
   const userId = $json.event.user;
   const channelId = $json.event.channel;
   
   // Create a session id (you could also hash this for security/length)
   const sessionId = `${userId}-${channelId}`;
   
   // Attach the session id to the JSON for further processing
   return {
     json: {
       ...$json,
       sessionId
     }
   };

2. Pass the Custom Session ID:
   Then, in your Postgres Chat Memory node, reference the custom session id using:

   JAVASCRIPTCopied
   {{ $json.sessionId }}

   This will allow the memory node to recognize and use the session id you generated for that particular conversation context.

Key Points to Remember

• Custom Generation: Since Slack doesn't provide a session id natively, it’s up to your workflow to generate and manage session linkage.
• Consistency: Ensure the logic for session id generation is applied consistently across all incoming Slack messages to maintain proper context retention.
• Memory Node Expectation: The Postgres Chat Memory node requires a consistent session key to store and retrieve past interactions effectively.

This approach should allow your Slack Q&A agent to work with Postgres memory, ensuring conversation context is maintained even though Slack doesn't inherently map a session id.