How to create the relationship between node by specific property?

[William_Lin]

Hello, everyone
I'm trying to create relationships between the existing Node by JsonList.

MATCH (n:Recipe) WHERE  n.id >5000 AND n.id<5040
WITH apoc.convert.fromJsonList(n.formula) AS datas, n
FOREACH (data in datas|
MERGE (:Scent{name:data.scent})-[:addDrop{drops:data.drops}]->(:Recipe{id:n.id}))

the Recipe( about n.formula) Json format is like below:

{....,
  "createdAt": "2017-04-09T05:37:12",
  **"formula": "[{"scent":"B9","drops":"1","color":"#E5127F"},{"scent":"M18","drops":"2","color":"#62B86A"},{"scent":"T24","drops":"5","color":"#F07736"},{"scent":"T44","drops":"3","color":"#84825E"},{"scent":"MA51","drops":"2","color":"#E86FA2"},{"scent":"BA69","drops":"3","color":"#84825E"}]"**,
  "id": 5001,
....
}

After I run this sctipt, I got the error :
Neo.ClientError.Schema.ConstraintValidationFailed
Node(154918) already exists with label Recipe and property id = 5001

How should I create the relationship to the existing node by specific property of the node (by id)?

[intouch_vivek]

William_Lin:

e node (by id

Hi @William_Lin,

Please look into below link

Neo4j Graph Database Platform

Creating and working with linked lists in Cypher - Neo4j Graph Database Platform

At some point when working with a graph, you may want to create a linked list out of some nodes. If each of the nodes to be linked has its own variable, this is easy, you just do a CREATE… Read more →

[William_Lin]

Hi Vivek,
Thanks a lot, I will try it.

[William_Lin]

William_Lin:

MATCH (n:Recipe) WHERE n.id >5000 AND n.id<5040 WITH apoc.convert.fromJsonList(n.formula) AS datas, n FOREACH (data in datas| MERGE (:Scent{name:data.scent})-[:addDrop{drops:data.drops}]->(:Recipe{id:n.id}))

I found I should MATCH existing node(:Recipe{id:n.id}) first, and then to connect the relationship inside FOREACH loop.

MATCH (n:Recipe) WHERE  n.id >5000 AND n.id<5040
WITH apoc.convert.fromJsonList(n.formula) AS datas, n
MATCH (q:Recipe{id:n.id})
FOREACH (data in datas|
MERGE (:Scent{name:data.scent})-[:addDrop{drops:data.drops}]->(q))

Thanks!