How to Connect Python to Neo4j Graph Database: Complete Guide

Neo4j is the world's leading graph database, designed to store and query highly connected data efficiently. When combined with Python, Neo4j enables developers to build powerful applications that leverage relationships between data points. This comprehensive guide covers everything you need to know about connecting Python to Neo4j.

Why Use Neo4j with Python?

Neo4j with Python offers powerful capabilities:

• Native graph storage optimized for relationships
• Powerful Cypher query language for pattern matching
• Excellent performance for traversing relationships
• ACID compliance for data integrity
• Real-time insights from connected data
• Perfect for social networks, recommendations, fraud detection
• Scalable architecture for enterprise applications
• Rich ecosystem of graph algorithms

Prerequisites

Before connecting Python to Neo4j, ensure you have:

• Python 3.6 or higher installed
• Neo4j database installed (Community or Enterprise)
• Basic understanding of graph databases and Cypher
• Neo4j connection details (URI, username, password)

Installing the Neo4j Driver

Install the official Neo4j Python driver:

bash

pip install neo4j

Basic Connection to Neo4j

Let's start with a simple connection:

python

from neo4j import GraphDatabase

# Connection details
uri = "bolt://localhost:7687"
username = "neo4j"
password = "your_password"

# Create driver
driver = GraphDatabase.driver(uri, auth=(username, password))

# Verify connectivity
driver.verify_connectivity()

print("Connected to Neo4j successfully!")

# Close driver
driver.close()

Connection with Error Handling

python

from neo4j import GraphDatabase
from neo4j.exceptions import ServiceUnavailable, AuthError

def create_neo4j_connection():
    try:
        driver = GraphDatabase.driver(
            "bolt://localhost:7687",
            auth=("neo4j", "password"),
            max_connection_lifetime=3600,
            max_connection_pool_size=50,
            connection_acquisition_timeout=120
        )
        
        # Verify connection
        driver.verify_connectivity()
        
        print("Successfully connected to Neo4j")
        
        # Get server info
        with driver.session() as session:
            result = session.run("CALL dbms.components() YIELD versions")
            version = result.single()[0][0]
            print(f"Neo4j version: {version}")
        
        return driver
        
    except ServiceUnavailable as e:
        print(f"Neo4j service unavailable: {e}")
        return None
    except AuthError as e:
        print(f"Authentication failed: {e}")
        return None
    except Exception as e:
        print(f"Error: {e}")
        return None

# Usage
driver = create_neo4j_connection()
if driver:
    driver.close()

Creating Nodes

python

from neo4j import GraphDatabase

driver = GraphDatabase.driver(
    "bolt://localhost:7687",
    auth=("neo4j", "password")
)

# Create a single node
with driver.session() as session:
    result = session.run("""
        CREATE (e:Employee {
            employee_id: $employee_id,
            first_name: $first_name,
            last_name: $last_name,
            email: $email,
            department: $department,
            salary: $salary
        })
        RETURN e
    """, employee_id="EMP001", first_name="John", last_name="Doe",
         email="john@company.com", department="Engineering", salary=75000)
    
    record = result.single()
    print(f"Created node: {record['e']}")

driver.close()

Creating Multiple Nodes

python

from neo4j import GraphDatabase

driver = GraphDatabase.driver(
    "bolt://localhost:7687",
    auth=("neo4j", "password")
)

# Create multiple nodes
employees = [
    {"id": "EMP001", "name": "John Doe", "dept": "Engineering"},
    {"id": "EMP002", "name": "Jane Smith", "dept": "Marketing"},
    {"id": "EMP003", "name": "Bob Johnson", "dept": "Sales"}
]

with driver.session() as session:
    for emp in employees:
        session.run("""
            CREATE (e:Employee {
                employee_id: $id,
                name: $name,
                department: $dept
            })
        """, id=emp["id"], name=emp["name"], dept=emp["dept"])
    
    print(f"Created {len(employees)} employee nodes")

driver.close()

Creating Relationships

python

from neo4j import GraphDatabase

driver = GraphDatabase.driver(
    "bolt://localhost:7687",
    auth=("neo4j", "password")
)

with driver.session() as session:
    # Create two nodes and relationship
    session.run("""
        CREATE (e1:Employee {employee_id: 'EMP001', name: 'John Doe'})
        CREATE (e2:Employee {employee_id: 'EMP002', name: 'Jane Smith'})
        CREATE (e1)-[:REPORTS_TO {since: date('2024-01-01')}]->(e2)
    """)
    
    print("Nodes and relationship created!")
    
    # Create relationship between existing nodes
    session.run("""
        MATCH (e1:Employee {employee_id: 'EMP003'})
        MATCH (e2:Employee {employee_id: 'EMP002'})
        CREATE (e1)-[:WORKS_WITH {project: 'ProjectX'}]->(e2)
    """)
    
    print("Relationship created between existing nodes!")

driver.close()

Querying Nodes

Find All Nodes

python

from neo4j import GraphDatabase

driver = GraphDatabase.driver(
    "bolt://localhost:7687",
    auth=("neo4j", "password")
)

with driver.session() as session:
    # Find all employee nodes
    result = session.run("""
        MATCH (e:Employee)
        RETURN e.employee_id, e.name, e.department
        ORDER BY e.name