📦 Neo4j Database Singleton (Python)

This project provides a simple implementation of a Singleton pattern for managing a Neo4j database connection in Python using the official driver.

🚀 Overview

The goal of this module is to ensure that:

• Only one database connection is created and reused
• Multiple calls return the same instance
• Connection management is centralized and controlled

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🧠 Concept

This implementation uses:

• A class-level static variable (db_driver)
• A classmethod to control access to the database connection
• A safeguard in __init__ to prevent multiple instantiations

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🛠️ Requirements

• Python 3.x
• Neo4j Python Driver

Install the dependency:

pip install neo4j

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▶️ Usage

Initialize the connection (once)

from database import Database

db = Database.getConnection("bolt://localhost:7687", "test_user", "root")

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Reuse the connection anywhere

from database import Database

db = Database.getConnection()

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Verify Singleton behavior

db1 = Database.getConnection("bolt://localhost:7687", "test_user", "root")
db2 = Database.getConnection()

print(db1 is db2)  # True

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Execute a query

from database import Database

driver = Database.getConnection()

with driver.session() as session:
    result = session.run("MATCH (n) RETURN n LIMIT 5")
    
    for record in result:
        print(record)

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Close the connection

driver = Database.getConnection()
driver.close()

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⚙️ How It Works

1. The first call to getConnection():

   • Creates a new Neo4j driver instance
   • Stores it in db_driver

2. Subsequent calls:

   • Return the existing instance
   • Ignore new parameters (if provided)

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⚠️ Limitations

• ❗ No connection validation (does not check if the connection is still alive)
• ❗ No support for multiple databases or environments
• ❗ Thread safety is not guaranteed
• ❗ Credentials cannot be updated after initialization

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💡 Possible Improvements

• Add connection health checks
• Support multiple environments (dev/staging/prod)
• Implement thread-safe Singleton
• Add connection pooling management
• Use context managers for sessions

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🧪 Example Use Case

Useful in:

• Small applications
• Scripts
• Prototypes
• Services where only one DB connection is needed

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📄 License

MIT License