docs/langchain/templates/neo4j-vector-memory/README.md

# neo4j-vector-memory

This template allows you to integrate an LLM with a vector-based retrieval system using Neo4j as the vector store.
Additionally, it uses the graph capabilities of the Neo4j database to store and retrieve the dialogue history of a specific user's session.
Having the dialogue history stored as a graph allows for seamless conversational flows but also gives you the ability to analyze user behavior and text chunk retrieval through graph analytics.


## Environment Setup

You need to define the following environment variables

```
OPENAI_API_KEY=<YOUR_OPENAI_API_KEY>
NEO4J_URI=<YOUR_NEO4J_URI>
NEO4J_USERNAME=<YOUR_NEO4J_USERNAME>
NEO4J_PASSWORD=<YOUR_NEO4J_PASSWORD>
```

## Populating with data

If you want to populate the DB with some example data, you can run `python ingest.py`.
The script process and stores sections of the text from the file `dune.txt` into a Neo4j graph database.
Additionally, a vector index named `dune` is created for efficient querying of these embeddings.


## 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-vector-memory
```

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

```shell
langchain app add neo4j-vector-memory
```

And add the following code to your `server.py` file:
```python
from neo4j_vector_memory import chain as neo4j_vector_memory_chain

add_routes(app, neo4j_vector_memory_chain, path="/neo4j-vector-memory")
```

(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=<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:

```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-vector-memory/playground](http://127.0.0.1:8000/neo4j-parent/playground)  

We can access the template from code with:

```python
from langserve.client import RemoteRunnable

runnable = RemoteRunnable("http://localhost:8000/neo4j-vector-memory")
```