Question

让我们假设这个模型：

(notification)-[:CONCERNS]->(user)

为了简单起见，让我们想象每个notification与特定主题相关的聊天条目相关。
因此，当用户进入Football主题并输入：＆＃34;嗨大家好！＆＃34;时，最终创建的notification包含这些属性（包括其他属性）：

topidId（String）
occurredOn（时间戳（长））
body（字符串 - 聊天消息的摘录）

请注意，notification和topic之间没有直接关系事实上，在未来，我不想用用户的通知机制污染Neo4j。
Redis或RDBMS可以更好地处理它。

基本上，如果我运行此查询：

MATCH (user:User {_id: "30c62b1f-4556-4966-b60c-3547d4c8d522"})
WITH user 
MATCH user<-[:CONCERNS]-(n:Notification)
RETURN n.topicId AS TopicId, n.body as Body
ORDER BY n.occurredOn DESC

它可以返回：

TopicID     Body
123         Fine and you !  // I want to retain only this for Football (123 being Football)
123         Hey! How are you?   
456         Yes, I'm here !  // I want to retain only this for tennis (456 being Tennis)
456         Are you here?

如何更改查询以获取此结果，作为每个主题的最新消息。

  123     Fine and you !
  456     Yes, I'm here !

Answer 1

这个怎么样？

MATCH (user:User {_id: "30c62b1f-4556-4966-b60c-3547d4c8d522"})
MATCH user<-[:CONCERNS]-(n:Notification)
WITH user, collect(n) AS notifications
ORDER BY n.occurredOn DESC
WITH user, notifications[0] AS notification
RETURN notification.topicId AS TopicId, notification.body as Body
ORDER BY notification.occurredOn DESC

Cypher /检索每个主题的最新通知

1 个答案: