How to Use Consistent UUIDs for message ID with useChat and FastAPI When Using streamResponse

[haya4ux]

I’m using the useChat hook from the AI SDK in a Next.js front end with a FastAPI back end, and I generate message IDs using uuidv4. I’m utilizing streamResponse for handling responses.

Currently, for messages with role: "user", I can successfully use the IDs generated on the client side and pass them to FastAPI, where they are processed correctly. However, I’m unsure how to handle the message IDs for role: "assistant" responses generated by the server.

Specifically, I have the following questions:

1. Is it possible to generate the ID on the client side and pass it to FastAPI for consistent use?

   • If so, how would I implement this effectively? An example of sending the ID from the client to FastAPI and ensuring it works well with streamResponse would be very helpful.

2. How would I handle ID generation on the server side and have it work seamlessly with useChat?

   • If the ID is generated on the FastAPI side, how should I pass this back to the client and ensure that the useChat hook uses this server-generated ID correctly, especially in the context of streamResponse?
   • Detailed steps or a code example on how to synchronize the server-generated ID with the local state of useChat would be greatly appreciated.

   I’m looking for guidance on which approach is generally recommended and how to implement it effectively with streamResponse.

[johnnyoshika]

Although my setup is a bit different, I have the same question about consistent IDs. I too can pick up the user message id by assigning true to sendExtraMessageFields in useChat:

useChat({
  sendExtraMessageFields: true, // Necessary to send message id
})

However, I'm not able to pick up the assistant id on the server, as it looks like it gets generated on the client.

My setup:

Node + express:

  const result = await streamText({
    model,
    messages,,
    onFinish: async event => {
      // I can't pick up the assistant ID here b/c it looks like it gets generated on the client and never gets sent to the server
      await onFinish(event.text);
    }
  });

  result.pipeDataStreamToResponse(res, {
    sendUsage: false,
  });

[QiaoLi1996]

Is any update? I'm also looking for pass the assistant id on the server to the client.data and setdata seem to work very well.

[johnnyoshika]

I haven't seen anything