AI Document Chat - RAG Introduction

March 5, 2025

📝 I've written a detailed blog post about RAG introduction. Check out this post!

A modern application that combines document processing with AI capabilities, allowing users to upload files and have natural conversations with an AI assistant about their content through semantic search and vector embeddings.

CategoryDetails
FrontendReact, TypeScript, Vite, TanStack Router/Query, Tailwind CSS, Shadcn UI
BackendHono, Drizzle ORM, PostgreSQL with pgvector
AI IntegrationMistral AI (embedding & mistral-large-latest), AI SDK
TypePersonal Project
StatusPrivate for now
CodePrivate for now

I'm a junior developer actively learning and building my skills. If you're interested in this project or would like to discuss potential job opportunities, please feel free to contact me directly.

Project Overview

This project demonstrates the implementation of Retrieval Augmented Generation (RAG) in a practical application. It enables users to upload documents of various formats (PDF, HTML, TXT) and engage in context-aware conversations with an AI assistant that can reference specific information from these documents.

AI Document Chat main interface showing document upload and list

Technical Implementation

The application architecture consists of a modern React frontend built with Vite and TypeScript, with a lightweight Hono-based Node.js backend. Document processing happens in multiple stages: parsing, chunking, generating embeddings using Mistral's mistral-embed model, and storing these vector representations in PostgreSQL using the pgvector extension. When users ask questions, the application retrieves relevant document chunks and uses Mistral's mistral-large-latest model to generate informative responses.

Interface showing a document being uploaded

Key Features

FeatureImplementation
Document ProcessingMulti-format support with automated chunking and embedding
Vector SearchSemantic similarity search using pgvector
AI Chat InterfaceStream-based responses with Mistral Large model
Document ManagementUpload and delete documents
Theme SupportDark/light mode
View of the chat messages

Development Challenges

Building this application presented several technical hurdles that required thoughtful solutions:

ChallengeSolution
Different Format TypesImplemented specialized handlers for PDF, HTML, and TXT formats
Chunking StrategyUsed Langchain text splitter with optimal overlap for context preservation
Vector Database IntegrationHow to add pgvector to a PostgreSQL database
Streaming ResponsesAI SDK integration with frontend and backend
View of the initial chat message

Architecture Overview

The RAG pipeline follows these key steps:

  1. Document upload and parsing to extract raw text
  2. Text chunking
  3. Vector embedding generation using Mistral embedding models
  4. Storage in PostgreSQL with pgvector for efficient similarity search
  5. Query processing that combines retrieved context with AI generation using Mistral's large language model

Learning Outcomes

This project provided extensive learning opportunities in:

  1. Vector database implementation
  2. LLM integration for document understanding
  3. Streaming AI responses
  4. Document processing pipelines
  5. Semantic search implementation
View of the settings

The project demonstrates how Retrieval Augmented Generation can significantly enhance applications by grounding responses in specific document contexts and providing more accurate information retrieval compared to traditional approaches.