LangChain Vector Database

Setup

uv pip install -U langchain langchain-community langchain-openai langchain-chroma openai agno

Example

agent_with_knowledge.py

import pathlib

from agno.agent import Agent
from agno.knowledge.knowledge import Knowledge
from agno.vectordb.langchaindb import LangChainVectorDb
from langchain_text_splitters import CharacterTextSplitter
from langchain_chroma import Chroma
from langchain_community.document_loaders import TextLoader
from langchain_openai import OpenAIEmbeddings

chroma_db_dir = pathlib.Path("./chroma_db")

# Load, split, and embed the documents with LangChain
raw_documents = TextLoader("data/state_of_the_union.txt", encoding="utf-8").load()
text_splitter = CharacterTextSplitter(chunk_size=1000, chunk_overlap=0)
documents = text_splitter.split_documents(raw_documents)
Chroma.from_documents(
    documents, OpenAIEmbeddings(), persist_directory=str(chroma_db_dir)
)

# Point Agno at the existing vectorstore
db = Chroma(
    embedding_function=OpenAIEmbeddings(), persist_directory=str(chroma_db_dir)
)
knowledge = Knowledge(
    vector_db=LangChainVectorDb(knowledge_retriever=db.as_retriever())
)

agent = Agent(knowledge=knowledge)
agent.print_response(
    "What did the president say about broadcasting and the State of the Union?",
    markdown=True,
)

LangChainVectorDb wraps a vectorstore you already manage with LangChain. Pass a retriever with knowledge_retriever, or pass the vectorstore itself with vectorstore and Agno creates a retriever on the first search.

LangChainVectorDb is search-only. insert() and upsert() raise NotImplementedError. Load documents through LangChain, then wire the retriever to Agno. Filter expressions are not supported. Dictionary filters apply only when Agno builds the retriever from vectorstore; a retriever passed with knowledge_retriever ignores them.

LangChainVectorDb Params

Parameter	Type	Default	Description
`vectorstore`	`Any`	`None`	A LangChain vectorstore instance. Used to create a retriever on first search if `knowledge_retriever` is not set.
`search_kwargs`	`dict`	`None`	Search parameters passed to `vectorstore.as_retriever()`. Defaults to `{"k": limit}` at search time.
`knowledge_retriever`	`Any`	`None`	A LangChain `BaseRetriever` instance. Takes precedence over `vectorstore`.
`name`	`str`	`None`	Name of the vector database.
`description`	`str`	`None`	Description of the vector database.

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LangChain Vector Database

Setup

Example

LangChainVectorDb Params

​Setup

​Example

​LangChainVectorDb Params

Setup

Example

LangChainVectorDb Params