Have you ever struggled to write complex SQL or graph database queries? What if you could just describe what you want in plain English and get the results directly? Thanks to advancements in natural language processing, tools like LangChain make this not only possible but incredibly intuitive.

In this article, I will demonstrate how to use Python, LangChain, and Neo4j to seamlessly query a graph database using natural language. LangChain will handle the conversion of natural language queries into Cypher queries, providing a streamlined and time-saving experience.

What is LangChain?

LangChain is an open-source framework designed to simplify the creation of applications that utilize large language models (LLMs). Whether you're building chatbots, question-answering systems, text summarizers, or tools for generating database queries, LangChain provides a robust foundation.

By leveraging LangChain, developers can quickly prototype and deploy applications that bridge the gap between natural language and machine intelligence.

Prerequisites

Before we dive in, ensure that you have Python and Neo4j installed on your system. If not, you can install them using the resources below:

• Download Python
• Download Neo4j

Alternatively, you can run Neo4j in Docker. Here’s the command to do so:

Run Neo4j in Docker

Setting Up the Environment

Install Python Dependencies

Install the necessary Python libraries by running the following command:

pip install --upgrade --quiet langchain langchain-neo4j langchain-openai langgraph

Download the Dataset

For this tutorial, we’ll use the Goodreads Book Datasets With User Rating 2M, which can be downloaded from here.

Load the Dataset into Neo4j

To populate the graph database with our dataset, use the following script:

Querying the Graph Database Using LangChain

With everything set up, we’ll now use LangChain to query the graph database using natural language. LangChain will process your input, convert it into a Cypher query, and return the results. For this demonstration, we’ll leverage the GPT-4o-mini model and the following tools:

Example Queries

Here are some sample queries and their results:

Query 1: Find all the books written by "J.K. Rowling" and published by "Bloomsbury Publishing".

Result:

• Harry Potter and the Sorcerer’s Stone: Rating: 4.8, Language: English
• Harry Potter and the Chamber of Secrets: Rating: 4.7, Language: English

Query 2: Who is the author of "The Lord of the Rings"?

Result: The author of "The Lord of the Rings" is J.R.R. Tolkien.

Query 3: Who is the author of "The Power of One"?

Result: The author of "The Power of One" is Bryce Courtenay.

Query 4: List books published by Penguin Books.

Result:
The following books are published by Penguin Books:

1. Untouchable - Rating: 3.72, Language: English
2. The Complete Verse and Other Nonsense - Rating: 4.18, Language: Not Available
3. The Beloved: Reflections on the Path of the Heart - Rating: 4.19, Language: English
4. Americana - Rating: 3.43, Language: English
5. Great Jones Street - Rating: 3.48, Language: English
6. Gravity’s Rainbow - Rating: 4.0, Language: English
7. City of Glass (The New York Trilogy, #1) - Rating: 3.79, Language: English
8. Ghosts (The New York Trilogy, #2) - Rating: 3.64, Language: English
9. Moon Palace - Rating: 3.94, Language: English
10. The Invention of Solitude: A Memoir - Rating: 3.78, Language: Not Available

Why Use Natural Language Queries?

Natural language querying offers numerous advantages:

1. Ease of Use: No need to memorize complex query languages like SQL or Cypher.
2. Efficiency: Quickly retrieve results without debugging intricate query syntax.
3. Accessibility: Enables non-technical users to interact with databases effortlessly.

Conclusion

LangChain combined with Neo4j demonstrates how powerful natural language processing can be in simplifying database interactions. This approach opens up possibilities for creating user-friendly tools like chatbots, question-answering systems, and even analytics platforms.

If you found this guide helpful or have any questions, feel free to share them in the comments below. Let’s continue exploring the limitless possibilities of natural language and AI-driven technologies!