循环在neo4j中创建或更新节点

Question

我是Neo4J的新手，所以我很坚持通过一些值循环。

技能列表

let data = [
  'big_data, business_intelligence',
  'big_data, data_collection',
  'big_data, economic_growth',
  'big_data, economy'
]

，我想创建或更新右侧左侧之间的关系

for (let item of data) {
    CreateSkillToSkillRelation(item);
}

const CreateSkillToSkillRelation = async (relation) => {
  let mainSkill = relation.split(",")[0];
  let secundarySkill = relation.split(",")[1];

  try {
    // Check if the relationship exists
    let { records } = await session.run(
      "MATCH(main:SKILL {name:$mainSkill}) -[relation:SKILL_TO_SKILL]-> (secundary:SKILL {name:$secundarySkill}) RETURN relation",
      { mainSkill, secundarySkill }
    );

    let count =
      records[0]?._fields[0].properties.count > 0
        ? records[0]._fields[0].properties.count + 1
        : 1;

    // If count is greater then 1 then lets update the counter
    if (count > 1) {
      await session.run(
        "MATCH(main:SKILL {name:$mainSkill}) -[relation:SKILL_TO_SKILL]-> (secundary:SKILL {name:$secundarySkill}) SET relation.count = $count RETURN main, secundary",
        {
          mainSkill,
          secundarySkill,
          count,
        }
      );
    }
    // Otherwise the skill relation is not created so lets create one
    else {
      await session.run(
        "CREATE(main:SKILL {name:$mainSkill}) -[:SKILL_TO_SKILL {count:$count}]-> (secundary:SKILL {name:$secundarySkill}) RETURN main, secundary",
        {
          mainSkill,
          secundarySkill,
          count,
        }
      );
    }

    await session.close();
  } catch (error) {
    console.log(error);
  }
};

我有技能串行的 开放交易；要么从交易中运行，要么使用其他会话。

有什么想法我该如何解决？

Answer 1

for (let item of data) {
    CreateSkillToSkillRelation(item);
}

不在等待您创造的承诺，因此您基本上试图与仅支持单个并发事务的单个会话同时运行所有这些承诺。

您应该在> CreateSkilltoskillRyation 的每个呼叫中​​创建一个会话，或使用单个会话等待每个呼叫。

尽管请注意，您可以在> CreateSkilltoSkillRyation 的末尾关闭会话，但仅在成功时，我建议您将等待session.close.close（）; 移动到最后一个块中。

Answer 2

1. 同事的答案 @just_another_dotnet_devev 是绝对正确的：您可以在循环中运行异步功能在其中一个。

2. 密码语言非常丰富，您可以使用它来完成尝试使用JavaScript循环进行的所有操作。像这样的东西，使用 和 merge < /a>：

   
   

---

const CreateSkillToSkillRelations = async (data) => {
  const session = driver.session();
  try {
    let { records } = await session.run(
        `WITH split(row, ',') as rels
         WITH trim(rels[0]) as mainSkill, 
              trim(rels[1]) as secundarySkill
         MERGE (main:SKILL {name: mainSkill})
               -[relation:SKILL_TO_SKILL]->
               (secundary:SKILL {name: secundarySkill})
           ON CREATE SET relation.count = 1
           ON MATCH SET relation.count = relation.count + 1
         RETURN main, relation, secundary`,
         { data }
    );
  } catch (error) {
    console.log(error);
  } finally {
    await session.close()
  }
};