Middleware Logging for generateObject and passing additional parameters to middleware

[LaurinBrechter]

I want to log my LLM calls in a middleware. Currently, this is my code for doing so:

export const loggingMiddleware: LanguageModelV1Middleware = {
  wrapGenerate: async ({ doGenerate, params }) => {
    const result = await doGenerate();

    if (result.response && result.response.modelId) {
      await db.insert(llmCallsTable).values({
        modelId: result.response.modelId,
        promptTokens: result.usage?.promptTokens,
        completionTokens: result.usage?.completionTokens,
        totalTokens:
          result.usage?.promptTokens + result.usage?.completionTokens,
      });
    } else {
      console.log("No modelId found in response");
    }

    return result;
  },
};

export const loggedGPT4oMini = experimental_wrapLanguageModel({
  model: openai("gpt-4o-mini"),
  middleware: loggingMiddleware,
});

Just to clarify, it seems that it is not possible to use generateObject with middleware. Is this correct?

And another question: Can I pass additional parameters to the experimental_wrapLanguageModel or loggedGPT4oMini function? In my example, I want to also save the function that called the language model in my logs. I guess one 'hack' would be to include the name of the function in the prompt or in the headers. But is there also another option?

export async function getTopics(resourceId: number) {

    const result = await generateText({
        model: loggedGPT4oMini,
        prompt: '',
        middlewareParams: {functionName: 'getTopics', resourceId: resourceId}
    })
}

[lgrammel]

Just to clarify, it seems that it is not possible to use generateObject with middleware. Is this correct?

No, that is not correct. The middleware works on the model level and wrapped models are usable in generateObject.

Re args: you can use factory functions for your middleware and pass in what's needed. Would that work?

[LaurinBrechter]

Hey, thanks for the quick reply. Yes, I had some other error when I called the function which made me think it wasn't possible with generateObject but now that's fixed. Okay, I'll look into factory functions (I think I never used them before that's probably why I didn't know this was a possibility here).