In this article, we will explore how to create a modern RAG (Retrieval-Augmented Generation) application utilizing Next.js 14 and LangChain. This application will allow you to build a custom chat interface that answers user questions based on your personalized data sources, specifically focusing on PDF documents as the primary data source.
To kick off, we’ll set up an API route named loadDocuments
. This route will be responsible for loading documents from your data source and storing them in a vector database. It is essential to understand the data structure and how documents can be loaded into the system.
The simplest way to load a PDF document is via LangChain's PDFLoader
. Here are the general steps:
Install Required Packages: Before diving into coding, ensure you have installed the necessary packages.
Setup PDF Loader: Use the following code snippet to initialize the loader:
const loader = new PDFLoader('path/to/your/document.pdf');
For multiple PDF documents stored locally, you’d utilize the MultiPDFLoader
function:
const loader = new MultiFileLoader(['path/to/doc1.pdf', 'path/to/doc2.pdf'], pdfLoaderHandler);
If your PDF files are stored externally (for instance, in a database), you would utilize the WebPDFLoader
. This approach requires reading the file data as binary data (blob):
const blob = await readFromDatabase(); // Function to fetch blob from your database
const loader = new WebPDFLoader(blob);
However, for multiple PDFs from the database, you would read and load each file, storing them in an array.
Once you have your documents loaded, you’ll want to split them into manageable chunks. You can use LangChain's RecursiveTextSplitter
to manage the size of chunks and how they overlap. For example, splitting into chunks of 1000 characters with an overlap of 200 characters:
const textSplitter = new RecursiveTextSplitter(( chunkSize: 1000, chunkOverlap: 200 ));
const chunks = textSplitter.splitDocuments(docs);
It's important to sanitize the content to prevent any parsing errors, particularly with characters such as backslashes.
Next, you will need to choose an embedding model and create a vector store for managing your embeddings. If you choose to use the Zeta
vector search, ensure you set up the associated database and table:
const zetaClient = new ZetaClient();
const vectorStore = new ZetaVectorStore(zetaClient, 'your-table-name');
Finally, add your documents to the vector store using the addDocuments
function.
After setting up your document loading and storage, it’s time to create the chatbot API, termed chatbot
. This API will handle user interactions and generate responses using a language model.
In the chatbot route, define necessary constants and helper functions. Key tasks include:
This could be accomplished like so:
const promptTemplate = "You're an assistant for Question Answering tasks. Use only the retrieved context and history to answer questions.";
Instantiate your language model, create a retriever from your vector store, and define a retrieval chain. This chain will leverage both your question history and current user inquiries to fetch necessary documents and generate responses.
Wrap your output using a streaming text response to handle the real-time chat interface. This allows for a seamless user experience as responses are generated.
With the backend API set up, we move to the UI aspect. Using React, create a chat interface:
Here is a simplified example for rendering messages:
messages.map((message, index) => (
<div key=(index) className=(message.role === 'user' ? 'user-message' : 'ai-message')>
<span>(message.role)</span>
<p>(message.content)</p>
</div>
))
Finally, remember to create a form for user input and submit their queries, linking everything to the chatbot API for interaction.
To see it in action, start your Next.js application using:
npm run dev
Before using the chatbot, ensure to run the loadDocuments
function to populate the vector database. Navigate to /chatbot
, where you should see your chat interface ready for interaction.
By following the steps outlined in this article, you can establish a custom RAG application using Next.js and LangChain. This interface allows users to query specific information based on the data you provide, demonstrating the powerful capabilities of combining these technologies.
RAG, Next.js, LangChain, API route, PDF documents, vector database, chatbot, user messages, AI responses, embedding model.
Q1: What is RAG? A1: RAG stands for Retrieval-Augmented Generation, which combines information retrieval with natural language generation to produce contextually relevant responses.
Q2: How do I load PDF documents into my application?
A2: You can use PDFLoader
for local documents or WebPDFLoader
for external PDFs. For multiple documents, MultiFileLoader
can be employed.
Q3: What is a vector store? A3: A vector store is a type of database specifically designed to manage and retrieve vectors generated from document embeddings, making it optimized for searching and analyzing large datasets.
Q4: Can the chatbot answer questions outside its knowledge base? A4: No, the current setup restricts the chatbot to answering questions based solely on the custom data provided through your document sources.
Q5: Is it possible to add more data sources later? A5: Yes, you can extend your application by integrating additional data sources and updating the vector store with new documents as needed.
In addition to the incredible tools mentioned above, for those looking to elevate their video creation process even further, Topview.ai stands out as a revolutionary online AI video editor.
TopView.ai provides two powerful tools to help you make ads video in one click.
Materials to Video: you can upload your raw footage or pictures, TopView.ai will edit video based on media you uploaded for you.
Link to Video: you can paste an E-Commerce product link, TopView.ai will generate a video for you.