Question

看起来像一个简单的错误，但我无法找到任何具体的信息，所以希望你能够了解这里发生的事情。

基本上我正在尝试迭代两组数据，为第一组创建元素，并根据某些条件将它们与第二组中的元素相关联。条件检查也是通过“foreach技巧”进行的，因此有2级嵌套FOREACH的

FOREACH (plc IN [{name:'bar2',id:'pepe'},{name:'foo2',id:'papa'},{name:'foo3',id:'paps'}] |
   MERGE (place:Place {id:plc.id})
   ON CREATE SET place = plc

   FOREACH (evt IN [{placename:'foo2',id:'pewpew'},{placename:'foo2',id:'powpow'},{placename:'bar2',id:'pawpaw'},{placename:'bar2',id:'pwaaagh'},{placename:'foo3',id:'pwaaagh'}] |

      FOREACH (ignoreme in CASE WHEN evt.placename = plc.name THEN [1] ELSE [] END |
         CREATE (e:Event)-[rel:IN]->(place) 
         SET e=evt
)))

快乐地咯咯地笑着Neo4j向我发出Unknown identifier "e"

Answer 1

我建议您在UNWIND之前使用FOREACH进行尝试。

WITH
  [{name:'bar2',id:'pepe'},{name:'foo2',id:'papa'},{name:'foo3',id:'paps'}] AS plcs,
  [{placename:'foo2',id:'pewpew'},{placename:'foo2',id:'powpow'},{placename:'bar2',id:'pawpaw'},{placename:'bar2',id:'pwaaagh'},{placename:'foo3',id:'pwaaagh'}] AS evts
UNWIND plcs AS plc
MERGE (place:Place {id:plc.id})
WITH place, plc, evts
UNWIND evts AS evt
WITH place, plc, evt
WHERE evt.placename = plc.name
CREATE (e:Event)-[:IN]->(place)
  SET e=evt

Answer 2

似乎是一个错误。您可以通过将较长的创建模式拆分为两个来解决它，以便创建e变量。

FOREACH (plc IN [{name:'bar2',id:'pepe'},{name:'foo2',id:'papa'},{name:'foo3',id:'paps'}] |
   MERGE (place:Place {id:plc.id})
   ON CREATE SET place = plc

   FOREACH (evt IN [{placename:'foo2',id:'pewpew'},{placename:'foo2',id:'powpow'},{placename:'bar2',id:'pawpaw'},{placename:'bar2',id:'pwaaagh'},{placename:'foo3',id:'pwaaagh'}] |

      FOREACH (ignoreme in CASE WHEN evt.placename = plc.name THEN [1] ELSE [] END |
         CREATE (e:Event)
         CREATE (e)-[rel:IN]->(place) 
         SET e=evt
)))

嵌套FOREACH语句检查中的未知标识符错误

2 个答案: