使用 Neo4j 和 Python 构建应用程序

pip install neo4j

from neo4j import GraphDatabase

# URI examples: "neo4j://localhost", "neo4j+s://xxx.databases.neo4j.io"
URI = "<URI for Neo4j database>"
AUTH = ("<Username>", "<Password>")

with GraphDatabase.driver(URI, auth=AUTH) as driver:
    driver.verify_connectivity()

# Get the name of all 42 year-olds
records, summary, keys = driver.execute_query(
    "MATCH (p:Person {age: $age}) RETURN p.name AS name",
    age=42,
    database_="neo4j",
)

# Loop through results and do something with them
for person in records:
    print(person)

# Summary information
print("The query `{query}` returned {records_count} records in {time} ms.".format(
    query=summary.query, records_count=len(records),
    time=summary.result_available_after,
))

from neo4j import GraphDatabase


URI = "<URI for Neo4j database>"
AUTH = ("<Username>", "<Password>")
employee_threshold=10


def main():
    with GraphDatabase.driver(URI, auth=AUTH) as driver:
        with driver.session(database="neo4j") as session:
            for i in range(100):
                name = f"Thor{i}"
                org_id = session.execute_write(employ_person_tx, name)
                print(f"User {name} added to organization {org_id}")


def employ_person_tx(tx, name):
    # Create new Person node with given name, if not exists already
    result = tx.run("""
        MERGE (p:Person {name: $name})
        RETURN p.name AS name
        """, name=name
    )

    # Obtain most recent organization ID and the number of people linked to it
    result = tx.run("""
        MATCH (o:Organization)
        RETURN o.id AS id, COUNT{(p:Person)-[r:WORKS_FOR]->(o)} AS employees_n
        ORDER BY o.created_date DESC
        LIMIT 1
    """)
    org = result.single()

    if org is not None and org["employees_n"] == 0:
        raise Exception("Most recent organization is empty.")
        # Transaction will roll back -> not even Person is created!

    # If org does not have too many employees, add this Person to that
    if org is not None and org.get("employees_n") < employee_threshold:
        result = tx.run("""
            MATCH (o:Organization {id: $org_id})
            MATCH (p:Person {name: $name})
            MERGE (p)-[r:WORKS_FOR]->(o)
            RETURN $org_id AS id
            """, org_id=org["id"], name=name
        )

    # Otherwise, create a new Organization and link Person to it
    else:
        result = tx.run("""
            MATCH (p:Person {name: $name})
            CREATE (o:Organization {id: randomuuid(), created_date: datetime()})
            MERGE (p)-[r:WORKS_FOR]->(o)
            RETURN o.id AS id
            """, name=name
        )

    # Return the Organization ID to which the new Person ends up in
    return result.single()["id"]


if __name__ == "__main__":
    main()

from neo4j import GraphDatabase


driver = GraphDatabase.driver(URI, auth=AUTH)
session = driver.session(database="neo4j")

# session/driver usage

session.close()
driver.close()