# neo4j_cypher This template allows you to interact with a Neo4j graph database in natural language, using an OpenAI LLM. It transforms a natural language question into a Cypher query (used to fetch data from Neo4j databases), executes the query, and provides a natural language response based on the query results. [![Diagram showing the workflow of a user asking a question, which is processed by a Cypher generating chain, resulting in a Cypher query to the Neo4j Knowledge Graph, and then an answer generating chain that provides a generated answer based on the information from the graph.](https://raw.githubusercontent.com/langchain-ai/langchain/master/templates/neo4j-cypher/static/workflow.png "Neo4j Cypher Workflow Diagram")](https://medium.com/neo4j/langchain-cypher-search-tips-tricks-f7c9e9abca4d) ## Environment Setup Define the following environment variables: ``` OPENAI_API_KEY= NEO4J_URI= NEO4J_USERNAME= NEO4J_PASSWORD= ``` ## Neo4j database setup There are a number of ways to set up a Neo4j database. ### Neo4j Aura Neo4j AuraDB is a fully managed cloud graph database service. Create a free instance on [Neo4j Aura](https://neo4j.com/cloud/platform/aura-graph-database?utm_source=langchain&utm_content=langserve). When you initiate a free database instance, you'll receive credentials to access the database. ## Populating with data If you want to populate the DB with some example data, you can run `python ingest.py`. This script will populate the database with sample movie data. ## Usage To use this package, you should first have the LangChain CLI installed: ```shell pip install -U langchain-cli ``` To create a new LangChain project and install this as the only package, you can do: ```shell langchain app new my-app --package neo4j-cypher ``` If you want to add this to an existing project, you can just run: ```shell langchain app add neo4j-cypher ``` And add the following code to your `server.py` file: ```python from neo4j_cypher import chain as neo4j_cypher_chain add_routes(app, neo4j_cypher_chain, path="/neo4j-cypher") ``` (Optional) Let's now configure LangSmith. LangSmith will help us trace, monitor and debug LangChain applications. You can sign up for LangSmith [here](https://smith.langchain.com/). If you don't have access, you can skip this section ```shell export LANGCHAIN_TRACING_V2=true export LANGCHAIN_API_KEY= export LANGCHAIN_PROJECT= # if not specified, defaults to "default" ``` If you are inside this directory, then you can spin up a LangServe instance directly by: ```shell langchain serve ``` This will start the FastAPI app with a server is running locally at [http://localhost:8000](http://localhost:8000) We can see all templates at [http://127.0.0.1:8000/docs](http://127.0.0.1:8000/docs) We can access the playground at [http://127.0.0.1:8000/neo4j_cypher/playground](http://127.0.0.1:8000/neo4j_cypher/playground) We can access the template from code with: ```python from langserve.client import RemoteRunnable runnable = RemoteRunnable("http://localhost:8000/neo4j-cypher") ```