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# Possible to pass any custom metadata in for middleware?

160 views · 3 likes · 3 posts


Jamie (@jamie-getlibretto) · 2025-04-11

I was looking to use the Middleware functionality to intercept calls, and send the event to our own service. Yet, I would like to be able to pass some custom "metadata" into the call. I was thinking just something as simlpe as:

```
const wrappedLlm = wrapLanguageModel({
    model: openai.chat('gpt-4o'),
    middleware: [loggingMiddleware]
});

const { text } = await generateText({
  model: wrappedLlm,
  messages: [{ role: 'user', content: 'Hello' }],
  metadata: {
    field1: "data 1",
    field2: "data 2",
  }
});
```

Is there anything like this? Is there someway i could handle this with the telemetry metadata?


Nico Albanese (@nicoalbanese) · 2025-04-14 · ♥ 3

Hey! You could use provider metadata for this:

```ts
import { openai } from '@ai-sdk/openai';
import { generateText, wrapLanguageModel, LanguageModelV1Middleware } from 'ai';
import 'dotenv/config';

export const yourLogMiddleware: LanguageModelV1Middleware = {
  wrapGenerate: async ({ doGenerate, params }) => {
    console.log('doGenerate called');
    console.log('METADATA', params.providerMetadata);

    const result = await doGenerate();

    console.log('doGenerate finished');
    console.log(`generated text: ${result.text}`);

    return result;
  },
};

const wrappedModel = wrapLanguageModel({
  model: openai('gpt-3.5-turbo'),
  middleware: yourLogMiddleware,
});

async function main() {
  const { text, usage } = await generateText({
    model: wrappedModel,
    prompt: 'Invent a new holiday and describe its traditions.',
    providerOptions: {
      yourLogMiddleware: {
        value1: 'hello',
        value2: 'world',
      },
    },
  });

  console.log(text);
  console.log();
  console.log('Usage:', usage);
}

main().catch(console.error);
```


Jamie (@jamie-getlibretto) · 2025-04-14

This is fantastic and exactly what we needed. Thanks!