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nicoalbanese merged 1 commit into from
Jul 8, 2025
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docs: update middleware for v5 beta #7127

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35 changes: 28 additions & 7 deletions content/docs/03-ai-sdk-core/40-middleware.mdx
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Original file line number Diff line number Diff line change
Expand Up @@ -182,7 +182,10 @@ Here are some examples of how to implement language model middleware:
This example shows how to log the parameters and generated text of a language model call.

```ts
import type { LanguageModelV2Middleware, LanguageModelV2StreamPart } from 'ai';
import type {
LanguageModelV2Middleware,
LanguageModelV2StreamPart,
} from '@ai-sdk/provider';

export const yourLogMiddleware: LanguageModelV2Middleware = {
wrapGenerate: async ({ doGenerate, params }) => {
Expand All @@ -204,14 +207,31 @@ export const yourLogMiddleware: LanguageModelV2Middleware = {
const { stream, ...rest } = await doStream();

let generatedText = '';
const textBlocks = new Map<string, string>();

const transformStream = new TransformStream<
LanguageModelV2StreamPart,
LanguageModelV2StreamPart
>({
transform(chunk, controller) {
if (chunk.type === 'text') {
generatedText += chunk.text;
switch (chunk.type) {
case 'text-start': {
textBlocks.set(chunk.id, '');
break;
}
case 'text-delta': {
const existing = textBlocks.get(chunk.id) || '';
textBlocks.set(chunk.id, existing + chunk.delta);
generatedText += chunk.delta;
break;
}
case 'text-end': {
console.log(
`Text block ${chunk.id} completed:`,
textBlocks.get(chunk.id),
);
break;
}
}

controller.enqueue(chunk);
Expand All @@ -236,7 +256,7 @@ export const yourLogMiddleware: LanguageModelV2Middleware = {
This example shows how to build a simple cache for the generated text of a language model call.

```ts
import type { LanguageModelV2Middleware } from 'ai';
import type { LanguageModelV2Middleware } from '@ai-sdk/provider';

const cache = new Map<string, any>();

Expand Down Expand Up @@ -270,7 +290,7 @@ This example shows how to use RAG as middleware.
</Note>

```ts
import type { LanguageModelV2Middleware } from 'ai';
import type { LanguageModelV2Middleware } from '@ai-sdk/provider';

export const yourRagMiddleware: LanguageModelV2Middleware = {
transformParams: async ({ params }) => {
Expand Down Expand Up @@ -299,7 +319,7 @@ Guard rails are a way to ensure that the generated text of a language model call
is safe and appropriate. This example shows how to use guardrails as middleware.

```ts
import type { LanguageModelV2Middleware } from 'ai';
import type { LanguageModelV2Middleware } from '@ai-sdk/provider';

export const yourGuardrailMiddleware: LanguageModelV2Middleware = {
wrapGenerate: async ({ doGenerate }) => {
Expand All @@ -323,7 +343,8 @@ To send and access custom metadata in Middleware, you can use `providerOptions`.

```ts
import { openai } from '@ai-sdk/openai';
import { generateText, wrapLanguageModel, LanguageModelV2Middleware } from 'ai';
import { generateText, wrapLanguageModel } from 'ai';
import type { LanguageModelV2Middleware } from '@ai-sdk/provider';

export const yourLogMiddleware: LanguageModelV2Middleware = {
wrapGenerate: async ({ doGenerate, params }) => {
Expand Down
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