Build RAG Chatbot with LangChain, Milvus, GPT-4o mini, and text-embedding-3-large
Retrieval-Augmented Generation (RAG) is a game-changer for GenAI applications, especially in conversational AI. It combines the power of pre-trained large language models (LLMs) like OpenAI’s GPT with external knowledge sources stored in vector databases such as Milvus and Zilliz Cloud, allowing for more accurate, contextually relevant, and up-to-date response generation.
This tutorial shows you how to build a simple RAG chatbot in Python using the following components:
- LangChain: An open-source framework that helps you orchestrate the interaction between LLMs, vector stores, embedding models, etc, making it easier to integrate a RAG pipeline.
- Milvus: An open-source vector database optimized for store, index, and search large-scale vector embeddings efficiently, perfect for use cases like RAG, semantic search, and recommender systems.
- GPT-4o mini : A compact, high-performance large language model developed by OpenAI.
- text-embedding-3-large: OpenAI's text embedding model, generating embeddings with 1536 dimensions, designed for tasks like semantic search and similarity matching.
By the end of this tutorial, you’ll have a functional chatbot capable of answering questions based on a custom knowledge base.
Note: Since we may use proprietary models in this process, make sure you have the required API key beforehand.
Step 1: Install and Set Up LangChain
Install LangChain and related modules:
%pip install --quiet --upgrade langchain-text-splitters langchain-community langgraph
Step 2: Install and Set Up GPT-4o mini
pip install -qU langchain-openai
import getpass
import os
if not os.environ.get("OPENAI_API_KEY"):
os.environ["OPENAI_API_KEY"] = getpass.getpass("Enter API key for OpenAI: ")
from langchain_openai import ChatOpenAI
llm = ChatOpenAI(model="gpt-4o-mini")
Step 3: Install and Set Up text-embedding-3-large
pip install -qU langchain-openai
import getpass
import os
if not os.environ.get("OPENAI_API_KEY"):
os.environ["OPENAI_API_KEY"] = getpass.getpass("Enter API key for OpenAI: ")
from langchain_openai import OpenAIEmbeddings
embeddings = OpenAIEmbeddings(model="text-embedding-3-large")
Step 4: Install and Set Up Milvus
pip install -qU langchain-milvus
from langchain_milvus import Milvus
vector_store = Milvus(
connection_args={"uri": "./milvus.db"},
embedding_function=embeddings,
auto_id=True,
drop_old=True,
)
Step 5: Build a RAG Chatbot
Now that you’ve set up all components, let’s start to build a simple chatbot. We’ll use the Milvus introduction doc as a private knowledge base. You can replace it with your own dataset to customize your RAG chatbot.
import bs4
from langchain import hub
from langchain_community.document_loaders import WebBaseLoader
from langchain_core.documents import Document
from langchain_text_splitters import RecursiveCharacterTextSplitter
from langgraph.graph import START, StateGraph
from typing_extensions import List, TypedDict
# Load and chunk contents of the blog
loader = WebBaseLoader(
web_paths=("https://milvus.io/docs/overview.md",),
bs_kwargs=dict(
parse_only=bs4.SoupStrainer(
class_=("doc-style doc-post-content")
)
),
)
docs = loader.load()
text_splitter = RecursiveCharacterTextSplitter(chunk_size=1000, chunk_overlap=200)
all_splits = text_splitter.split_documents(docs)
# Index chunks
_ = vector_store.add_documents(documents=all_splits)
# Define prompt for question-answering
prompt = hub.pull("rlm/rag-prompt")
# Define state for application
class State(TypedDict):
question: str
context: List[Document]
answer: str
# Define application steps
def retrieve(state: State):
retrieved_docs = vector_store.similarity_search(state["question"])
return {"context": retrieved_docs}
def generate(state: State):
docs_content = "\n\n".join(doc.page_content for doc in state["context"])
messages = prompt.invoke({"question": state["question"], "context": docs_content})
response = llm.invoke(messages)
return {"answer": response.content}
# Compile application and test
graph_builder = StateGraph(State).add_sequence([retrieve, generate])
graph_builder.add_edge(START, "retrieve")
graph = graph_builder.compile()
Test the Chatbot
Yeah! You've built your own chatbot. Let's ask the chatbot a question.
response = graph.invoke({"question": "What data types does Milvus support?"})
print(response["answer"])
Example Output
Milvus supports various data types including sparse vectors, binary vectors, JSON, and arrays. Additionally, it handles common numerical and character types, making it versatile for different data modeling needs. This allows users to manage unstructured or multi-modal data efficiently.
What Have You Learned?
You've learned how to build a complete RAG pipeline, implementing vector similarity search with Milvus and contextual response generation with GPT-4o mini. Through hands-on development, you've discovered how to optimize document chunking for better retrieval and manage application state with LangGraph. You've also learned practical implementation details like setting up API authentication and configuring vector stores. While this tutorial covered the basics, RAG systems are incredibly versatile - you can extend this foundation by using different document sources, embedding models, or LLMs to create increasingly sophisticated AI applications.
We'd Love to Hear What You Think!
We’d love to hear your thoughts! 🌟 Join our vibrant Milvus Discord community to share your experiences, ask questions, or connect with thousands of AI enthusiasts. Your journey matters to us!
If you like this tutorial, show your support by giving our Milvus GitHub repo a star ⭐—it means the world to us and inspires us to keep creating! 💖
Further Resources
🌟 In addition to this RAG tutorial, unleash your full potential with these incredible resources to level up your RAG skills.
- Step 1: Install and Set Up LangChain
- Step 2: Install and Set Up GPT-4o mini
- Step 3: Install and Set Up text-embedding-3-large
- Step 4: Install and Set Up Milvus
- Step 5: Build a RAG Chatbot
- What Have You Learned?
- We'd Love to Hear What You Think!
- Further Resources
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