neo4j图库

一.neo4j认识

neo4j官方驱动支持Python语言，驱动程序主要包含Driver类型和Session类型。Driver对象包含Neo4j数据库的详细信息，包括主机url、安全验证等配置，还管理着连接池（Connection Pool）；Session对象是执行事务单元的逻辑上下文，事务是在Session的上下文中执行的。由于Session不是线程安全的，并能够从Driver对象管理的连接池中回收利用（Recycle）连接，因此，Session对象是轻量级的（lightweight），用完之后应立即销毁（disposable）。

Driver对象和Session对象的关系是：Driver对象负责管理连接池，从连接池中分配连接创建Session对象；Session对象在单个线程中接收Cypher和启动事务，在事务执行完成之后，立即销毁Session对象；Driver对象负责回收连接，等待为下一个Session对象分配连接。

在neo4j中，一个node节点也算是一个图(如果用py2neo来操作的话，会清楚的感受到)，create创建是会重复创建的，但是merge不会，merge只会更新多的部分

二.使用neo4j驱动操作python

https://zhuanlan.zhihu.com/p/82958776

https://www.cnblogs.com/ljhdo/p/10907941.html

1.安装

pip install neo4j-driver
# 或者pip install neo4j-driver==1.4.0

2.例子(使用驱动运行cypher语句)

driver.session().run("cypher语句")，可增删改查

from neo4j import GraphDatabase

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

def add_friend(tx, name, friend_name):
    tx.run("MERGE (a:Person {name: $name}) "
           "MERGE (a)-[:KNOWS]->(friend:Person {name: $friend_name})",
           name=name, friend_name=friend_name)

def print_friends(tx, name):
    for record in tx.run("MATCH (a:Person)-[:KNOWS]->(friend) WHERE a.name = $name "
                         "RETURN friend.name ORDER BY friend.name", name=name):
        print(record["friend.name"])

with driver.session() as session:
    session.write_transaction(add_friend, "Arthur", "Guinevere")
    session.write_transaction(add_friend, "Arthur", "Lancelot")
    session.write_transaction(add_friend, "Arthur", "Merlin")
    session.read_transaction(print_friends, "Arthur")

三.使用py2neo模块操作python

1.创建节点(关系)

from py2neo import Node,Relationship,Graph,NodeMatcher
graph = Graph("http://47.100.10.149:7474", auth=("neo4j", "neo4j@cnic"))
node1 = Node("Lable", id="xx1",name="XX1") #参数一为节点标签，之后的为节点属性
node2 = Node("Lable", id="xx2",name="XX2")
#Realationship(start_node,"关系名称",end_node,关系属性)
re = Realationship(node1,"关系名称",node2,id="X",name="x")  
graph.create(node1)
graph.create(node2)
graph.create(re)

使用cursor

from py2neo import Node,Relationship,Graph,NodeMatcher
graph = Graph("http://47.100.10.149:7474", auth=("neo4j", "neo4j@cnic"))
node1 = Node("Lable", id="xx1",name="XX1") #参数一为节点标签，之后的为节点属性
node2 = Node("Lable", id="xx2",name="XX2")
re = Realationship(node1,"关系名称",node2,id="X",name="x")  
#Realationship(start_node,"关系名称",end_node,关系属性)
nodes = [node1,node2]
nodes_relations = [re]
cursor = graph.begin()
sub = Subgraph(nodes=nodes, relationships=nodes_relations)
cursor.create(sub)
cursor.commit()

删除，删除带关系的节点，要先删除关系，可使用graph.separte

from py2neo import Graph, NodeMatcher

graph = Graph("http://47.100.10.149:7474",auth=("neo4j","neo4j@cnic"))
matcher = NodeMatcher(graph)
node_label = "Person2"
node_list = matcher.match(node_label)
for i in node_list:
    graph.delete(i)

查某个label下的节点的所有关系

 nodes = matcher.match("Instrument3")
    relations = []
    for node in nodes:
        relation_list = RelationshipMatcher(graph).match((node,))
        for relation in relation_list:
            print(relation)