app1.py

from langchain_community.document_loaders import WebBaseLoader
from langchain.vectorstores.chroma import Chroma
from langchain_community import embeddings
from langchain_community.chat_models import ChatOllama
from langchain_core.runnables import RunnablePassthrough
from langchain_core.output_parsers import StrOutputParser
from langchain_core.prompts import ChatPromptTemplate
from langchain_text_splitters import CharacterTextSplitter

model_local = ChatOllama(model="mistral-openorca")

#1. Split data into chunks
urls = [
    "https://svelte.dev/blog/runes",
    "https://svelte-5-preview.vercel.app/docs/runes",
    "https://svelte.dev/blog/whats-new-in-svelte-january-2024",
    "https://medium.com/@flavio.pinnelli/svelte-5-how-runes-change-the-game-dc7773549c7a",
]

docs = [WebBaseLoader(url).load() for url in urls]
docs_list = [item for sublist in docs for item in sublist]
text_splitter = CharacterTextSplitter.from_tiktoken_encoder(chunk_size=7500, chunk_overlap=100)
docs_splits = text_splitter.split_documents(docs_list)

#2. Convert documents to embeddings and store them
vectorstore = Chroma.from_documents(
    documents=docs_splits,
    collection_name="rag-chroma",
    embedding=embeddings.ollama.OllamaEmbeddings(model='nomic-embed-text'),
)

retriever = vectorstore.as_retriever()

#3. Before RAG
print("Before Rag\n")
before_rag_template = "What do you know about {topic}"
before_rag_prompt = ChatPromptTemplate.from_template(before_rag_template)
before_rag_chain = before_rag_prompt | model_local | StrOutputParser()
print(before_rag_chain.invoke({"topic": "Svelte 5"}))

#4 After RAG
print("\n########\nAfter RAG\n")
after_rag_template = """Answer the question based only on the following context: 
{context}
Question: {question}
"""

after_rag_prompt = ChatPromptTemplate.from_template(after_rag_template)
after_rag_chain = (
    {"context": retriever, "question": RunnablePassthrough()}
    | after_rag_prompt
    | model_local
    | StrOutputParser()
)

print(after_rag_chain.invoke("What do you know about Svelte 5?"))