Neo4j-列表字符串转数字列表

• 问题来自一个需求：用load csv导入neo4j时，数字列表变成了字符串，需要把它转回列表状态。

  由于手头没有原始数据，这里用其他数据库进行实验。

• Neo4j版本：community-4.2

• 时间：2022-10-21

方案一

• 模拟一个列表字符串，保存为节点属性

  MATCH (n:IndustryChain{name:'主动元件'}) 
  set n.list = '[1,2,3,4]'
  

• 尝试去掉字符串中的括号，然后拆分为列表

  MATCH (n:IndustryChain{name:'主动元件'}) 
  with substring(n.list,1,7) as numstr,n
  with split(numstr,',') as nlist, n
  set n.list = nlist
  

• 将列表中元素转为整型，修改节点属性为新列表

  MATCH (n:IndustryChain{name:'主动元件'}) 
  with [num in n.list | toInteger(num) ] as numlist,n
  set n.list = numlist
  return n.list
  

• 整合上述步骤

  MATCH (n:IndustryChain{name:'主动元件'}) 
  with substring(n.list,1,7) as numstr,n
  with split(numstr,',') as nlist, n
  with [num in nlist | toInteger(num) ] as numlist,n
  set n.list = numlist
  

• 由于列表长度不固定，且没找到获取字符串长度的函数，用replace方式去除括号

  MATCH (n:IndustryChain{name:'主动元件'}) 
  with replace(n.list, "[", "") as strL,n
  with replace(n.list, "]", "") as numstr,n
  with split(numstr,',') as nlist, n
  with [num in nlist | toInteger(num) ] as numlist,n
  set n.list = numlist
  

方案二

• 新命令：

  MATCH (n:IndustryChain{name:'主动元件'}) 
  with replace(n.list, "[", "") as strL,n
  with replace(n.list, "]", "") as numstr,n
  with split(numstr,',') as nlist, n
  with [num in nlist | toInteger(num) ] as numlist,n
  set n.list = numlist
  

相关知识：

• String functions - Neo4j Cypher Manual
  • substring(n.list,1,7)
  • replace(n.list, "[", "")
  • split(numstr,',')
• Lists - Neo4j Cypher Manual
  • [num in nlist | toInteger(num) ]
• SET - Neo4j Cypher Manual
  • set命令