图数据库neo4j(三)python 连接neo4j，实现增删改查

图数据库neo4j(二)python 连接neo4j
更多可以阅读https://blog.csdn.net/column/details/23835.html

环境

py2neo—3.1.2、
python3.6。
neo4j3.5

增删改查

连接neo4j

# -*- coding: utf-8 -*-

from py2neo import Graph, Node, Relationship, NodeSelector 
graph = Graph("http://localhost:7474", username="neo4j", password='password')

清空库

graph.delete_all()

创建节点

'''
1 —— 创建node，函数第一个参数是节点类型，第二个参数是value值
'''
a = Node('PersonTest', name='张三')
b = Node('PersonTest', name='李四')
r = Relationship(a, 'KNOWNS', b)
s = a | b | r
graph.create(s)

Node查询

Input：

# 用CQL进行查询，返回的结果是list
data1 = graph.data('MATCH(p:PersonTest) return p')
print("data1 = ", data1, type(data1))

output:整体输出，并未单条输出

data1 =  [{'p': (ab38fb4:PersonTest {name:"张三"})}, {'p': (ec86073:PersonTest {name:"李四"})}] <class 'list'>

Input：find_one方法

# 用find_one()方法进行node查找，返回的是查找node的第一个node
data2 = graph.find_one(label='PersonTest', property_key='name', property_value="李四")
print ("data2 = ", data2, type(data2))

output:输出一条

data2 =  (ec86073:PersonTest {name:"李四"}) <class 'py2neo.types.Node'>

Input：find方法，遍历输出单条

# 用find()方法进行node查找,需要遍历输出，类似于mongodb
data3 = graph.find(label='PersonTest')
for data in data3:
    print ("data3 = ", data)

output：

data3 =  (ab38fb4:PersonTest {name:"张三"})
data3 =  (ec86073:PersonTest {name:"李四"})

关系查询

'''
3　——　Relationship查询
'''
relationship = graph.match_one(rel_type='KNOWNS')
print (relationship, type(relationship))

Output:

(b55c600)-[:KNOWNS]->(b811b1f) <class 'py2neo.types.Relationship'>

更新push

'''
    4 —— 更新Node的某个属性值，若node没有该属性，则新增该属性
'''
node1 = graph.find_one(label='PersonTest', property_key='name', property_value="张三")
node1['age'] = 21
graph.push(node1)
data4 = graph.find(label='PersonTest')
for data in data4:
    print ("data4 = ", data)

output:

data4 =  (a2d68e1:PersonTest {age:21,name:"张三"})
data4 =  (e4a1ab9:PersonTest {name:"李四"})

基于上面的操作，再次定义node1[‘age’] = 99,并执行graph.push(node1)，发现已经更新

node1['age'] = 99
graph.push(node1)
data5 = graph.find(label='PersonTest')
for data in data5:
    print ("data5 = ", data)

output:

data5 =  (a2d68e1:PersonTest {age:99,name:"张三"})
data5 =  (e4a1ab9:PersonTest {name:"李四"})

删除node与relationship

'''
    5 —— 删除某node，在删除node之前需要先删除relationship
'''
node = graph.find_one(label='PersonTest', property_key='name', property_value="李四")
relationship = graph.match_one(rel_type='KNOWNS')
graph.delete(relationship)
graph.delete(node)
data6 = graph.find(label='PersonTest')
for data in data6:
    print ("data6 = ", data)

output:

没有输出

多条件查询

'''
    6 —— 多条件查询
'''
a = Node('PersonTest', name='张三', age=21, location='广州')
b = Node('PersonTest', name='李四', age=22, location='上海')
c = Node('PersonTest', name='王五', age=21, location='北京')
r1 = Relationship(a, 'KNOWS', b)
r2 = Relationship(b, 'KNOWS', c)
s = a | b | c | r1 | r2
graph.create(s)
data7 = graph.find(label='PersonTest')
for data in data7:
    print ("data7 = ", data)

output:

data7 =  (`张三`:PersonTest {age:21,location:"广州",name:"张三"})
data7 =  (`李四`:PersonTest {age:22,location:"上海",name:"李四"})
data7 =  (`王五`:PersonTest {age:21,location:"北京",name:"王五"})

NodeSelector-select单条件查询，返回的是多个结果

# 单条件查询，返回的是多个结果
selector = NodeSelector(graph)
persons = selector.select('PersonTest', age=21)
print("data8 = ", list(persons))

output:整体一条输出

data8 =  [(ca77b49:PersonTest {age:21,location:"广州",name:"张三"}), (a4efa9c:PersonTest {age:21,location:"北京",name:"王五"})]

多条件查询

# 多条件查询
selector = NodeSelector(graph)
persons = selector.select('PersonTest', age=21, location='广州')
print("data9 = ", list(persons))

output:

data9 =  [(c14b444:PersonTest {age:21,location:"广州",name:"张三"})]

orderby

# orderby进行更复杂的查询
selector = NodeSelector(graph)
persons = selector.select('PersonTest').order_by('_.age')
for data in persons:
    print ("data10 = ", data)

data10 =  (a3c4b1d:PersonTest {age:21,location:"广州",name:"张三"})
data10 =  (a6492e5:PersonTest {age:21,location:"北京",name:"王五"})
data10 =  (e155f3b:PersonTest {age:22,location:"上海",name:"李四"})

整理日期：2018-08-16

参考文献:https://py2neo.org/v4/database.html#the-graph