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This template turns Cohere into a librarian.

It demonstrates the use of a router to switch between chains that can handle different things: a vector database with Cohere embeddings; a chat bot that has a prompt with some information about the library; and finally a RAG chatbot that has access to the internet.

For a fuller demo of the book recomendation, consider replacing books_with_blurbs.csv with a larger sample from the following dataset: .

Environment Setup​

Set the COHERE_API_KEY environment variable to access the Cohere models.


To use this package, you should first have the LangChain CLI installed:

pip install -U langchain-cli

To create a new LangChain project and install this as the only package, you can do:

langchain app new my-app --package cohere-librarian

If you want to add this to an existing project, you can just run:

langchain app add cohere-librarian

And add the following code to your file:

from cohere_librarian.chain import chain as cohere_librarian_chain

add_routes(app, cohere_librarian_chain, path="/cohere-librarian")

(Optional) Let's now configure LangSmith. LangSmith will help us trace, monitor and debug LangChain applications. LangSmith is currently in private beta, you can sign up here. If you don't have access, you can skip this section

export LANGCHAIN_API_KEY=<your-api-key>
export LANGCHAIN_PROJECT=<your-project> # if not specified, defaults to "default"

If you are inside this directory, then you can spin up a LangServe instance directly by:

langchain serve

This will start the FastAPI app with a server is running locally at http://localhost:8000

We can see all templates at http://localhost:8000/docs We can access the playground at http://localhost:8000/cohere-librarian/playground

We can access the template from code with:

from langserve.client import RemoteRunnable

runnable = RemoteRunnable("http://localhost:8000/cohere-librarian")