如何在 Neo4j 中将结果值从一条语句传递到另一条语句

Question

我有下面的代码，它运行多个语句，第一个语句应该return一个结果被第二个语句[=19使用=], 是来自 android app.

的调用
return session.writeTransaction(wrte=>{ let r : any if(context.auth){ //This Statement returns ID of the node wrte.run('MATCH (p:Person{identity:{identity}}) CREATE (p)-[po:POST]->(a:Post{post:{post},userName:{userName}}) RETURN ID(a)', {identity: context.auth.uid, post: data.post, userName: context.auth.token.name }) } return r as neo4j.v1.StatementResult }) //how to get the ID from the Last Statement .then((val) => session.readTransaction(read => { console.log(val.records[0].get(0)) return read.run('MATCH (p:Post) WHERE id(p) = {any} RETURN p',{any: val.records[0].get(0)}) })) .then(result => { session.close(); driver.close() console.log(result) var singleRecord = result.records[0] var dat = singleRecord.get(0) if(result.records[0] == null){ return null } else { return { "post": dat.properties.post, "userName":dat.properties.userName, } } }).catch(error => { session.close() console.log(error) driver.close() throw new functions.https.HttpsError(error,"some error"); }) });

console.log(val.records[0].get(0)) return未定义，如何正确传递结果以及如何检索 ID？

Answer 1

在你的 Cypher 声明中，你写了 RETURN ID(a)。因此，您需要在 StatementResult 上访问的密钥称为 ID(a).

使用val.records[0].get('ID(a)').

注意：如果您为该值设置别名（例如 RETURN ID(a) AS id），那么您将执行 val.records[0].get('id').

Answer 2

我只需要 return 每 笔交易

代码：

return session.writeTransaction(wrte=>{
    let r : any

    if(context.auth){
      r = wrte.run('MATCH (p:Person{identity:{identity}}) CREATE (p)-[po:POST]->(a:Post{post:{post},userName:{userName}}) RETURN ID(a) AS id', 
           {identity: context.auth.uid, post: data.post, userName: context.auth.token.name  })
    }

   return r as neo4j.v1.StatementResult
  }

)

  .then((r) => {
    return session.readTransaction(tx =>
      tx.run('MATCH  (p:Post) WHERE id(p) = {v} RETURN p',{v: r.records[0].get(0)})
    )

    .then(result => {
      session.close();      
      driver.close()
      var singleRecord = result.records[0]
      var dat = singleRecord.get(0)

      if(result.records[0] == null){

        return  null
        //response.send(false) 
      } else {
        return {

          "post": dat.properties.post,
          "dateTime":dat.properties.dateTime
      }
        //response.send(true) 
      }
    }).catch(error => {
      session.close()
      console.log(error)
      driver.close()
      throw new functions.https.HttpsError(error,"some error");
    })
  })
}
)

Answer 3

您的第一个查询可以只 return a 节点，无需进行第二个查询。这样效率会高很多。

而不是这个：

MATCH (p:Person{identity:{identity}})
CREATE (p)-[po:POST]->(a:Post{post:{post},userName:{userName}})
RETURN ID(a) AS id`

这样做：

MATCH (p:Person{identity:{identity}})
CREATE (p)-[po:POST]->(a:Post{post:{post},userName:{userName}})
RETURN a

如何在 Neo4j 中将结果值从一条语句传递到另一条语句

How to pass result value from one statement to another in Neo4j

typescript

neo4j

cypher

google-cloud-functions

neo4j-driver