Return writer for lang-chain stream. (#517)

Co-authored-by: Max Leiter <max.leiter@vercel.com>
vercel · Aug 28, 2023 · bbf4403 · bbf4403
1 parent 8a2cbaf
commit bbf4403
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diff --git a/.changeset/quick-shrimps-smash.md b/.changeset/quick-shrimps-smash.md
@@ -0,0 +1,5 @@
+---
+'ai': patch
+---
+
+langchain-stream: return langchain `writer` from LangChainStream
diff --git a/docs/pages/docs/api-reference/langchain-stream.mdx b/docs/pages/docs/api-reference/langchain-stream.mdx
@@ -37,7 +37,7 @@ export const runtime = 'edge'
 
 export async function POST(req: Request) {
   const { messages } = await req.json()
-  const { stream, handlers } = LangChainStream()
+  const { stream, handlers, writer } = LangChainStream()
 
   const llm = new ChatOpenAI({
     streaming: true

diff --git a/packages/core/streams/langchain-stream.ts b/packages/core/streams/langchain-stream.ts
@@ -35,6 +35,7 @@ export function LangChainStream(callbacks?: AIStreamCallbacksAndOptions) {
       .pipeThrough(
         createStreamDataTransformer(callbacks?.experimental_streamData)
       ),
+    writer,
     handlers: {
       handleLLMNewToken: async (token: string) => {
         await writer.ready