web document loading

src/index.js

@@ -1,23 +1,67 @@
 import 'dotenv/config';
-import { ChatOpenAI } from "@langchain/openai";
+process.env.OPENAI_API_KEY;
+import { ChatOpenAI, OpenAIEmbeddings } from "@langchain/openai";
 import { ChatPromptTemplate } from "@langchain/core/prompts";
 import { StringOutputParser } from "@langchain/core/output_parsers";
+import { MemoryVectorStore } from "langchain/vectorstores/memory";
+import { createRetrievalChain } from "langchain/chains/retrieval";
+import { createStuffDocumentsChain } from "langchain/chains/combine_documents";
+
+import { CheerioWebBaseLoader } from "langchain/document_loaders/web/cheerio";
+import { RecursiveCharacterTextSplitter } from "langchain/text_splitter";
+
+const chatModel = new ChatOpenAI({});
+const loader = new CheerioWebBaseLoader(
+  "https://docs.smith.langchain.com/"
+);
+
+const docs = await loader.load();
+
+const splitter = new RecursiveCharacterTextSplitter();
+
+const splitDocs = await splitter.splitDocuments(docs);
+
+const embeddings = new OpenAIEmbeddings();
+
+const vectorstore = await MemoryVectorStore.fromDocuments(
+  splitDocs,
+  embeddings
+);
+
+const retriever = vectorstore.asRetriever();
+
+const prompt =
+  ChatPromptTemplate.fromTemplate(`Answer the following question based only on the provided context:
+
+<context>
+{context}
+</context>
+
+Question: {input}`);
+
+const documentChain = await createStuffDocumentsChain({
+  llm: chatModel,
+  prompt,
+});
+
+const retrievalChain = await createRetrievalChain({
+  combineDocsChain: documentChain,
+  retriever,
+});
 
 const outputParser = new StringOutputParser();
 
-const prompt = ChatPromptTemplate.fromMessages([
+// const prompt = ChatPromptTemplate.fromMessages([
-  ["system", "You are an old farmer"],
+//   ["system", "You are an old farmer"],
-  ["user", "{input}"],
+//   ["user", "{input}"],
-]);
+// ]);
 
-process.env.OPENAI_API_KEY;
 
-const chatModel = new ChatOpenAI({});
 
-const chain = prompt.pipe(chatModel).pipe(outputParser);
+// const chain = prompt.pipe(chatModel).pipe(outputParser);
 
-const res = await await chain.invoke({
+const res = await retrievalChain.invoke({
-  input: "Write a beautiful poem no longer than 5 lines including the phrase 'hello world'",
+  input: "What is langsmith",
 });
 
 console.log(res);