Neo4j：如何将多个密码合二为一？

Question

我有一个带有常用社交图的 Neo4j 数据库。我正在尝试创建一个活动源（用户 X 关注了你，用户 Y 喜欢了你的消息等）

有User 和Message 节点。

还有Follows、Likes 和Mentions 关系，每个关系都有一个created_on 属性。

（实际上我想要更多的关系，但为了简洁起见，我将其保留为 3 以作为示例）

我正在尝试返回一个活动事件列表，按日期分页和排序。每个活动都会有它发生的日期、与之相关的用户和消息（如果适用）。

我对每种活动类型/关系都有此工作，但我正在努力将它们全部组合成一个密码/响应。

Cyphers 分别是……

喜欢

MATCH (me:User {username:"matt"})-[:Owner]->(msg:Message)<-[likes:Likes]-(user:User) RETURN user, msg, likes.created_on ORDER BY likes.created_on LIMIT 25

提及

MATCH (me:User {username:"matt"})<-[mentions:Mentions]-(msg:Message)-[:Owner]-(user:User) RETURN user, msg, mentions.created_on ORDER BY mentions.created_on LIMIT 25

关注

MATCH (me:User {username:"Matt"})<-[follows:Follows]-(user:User) RETURN user, follows.created_on ORDER BY follows.created_on LIMIT 25

我最初将它们全部与optional 组合在一起，但这会返回每行不止一个结果/关系类型。因此，一个 Activity 可以同时具有 comment 和 mention。这会弄乱限制请求，因为我们有 2 个活动占用一个结果。

然后我尝试了WHERE 和OR

 MATCH (me:User {username:"Matt"})-[r]-(m)--(u)
    WHERE me-[:Owner]->(m:Message)<-[r:Likes]-(u:User)
    OR me<-[r:Message]-(m:Message)-[:Owner]-(u:User)
    OR me<-[r:Follows]-(u:User)
    RETURN m, u, r.created_on
    ORDER BY r.created_on
    LIMIT 25

但我现在迷路了！这似乎根本没有返回任何结果

关于如何将上述密码组合到一个请求中的任何建议/指针？

Answer 1

试试这样的

MATCH (me:User {username:"matt"})
OPTIONAL MATCH (me)-[:Owner]->(msg:Message)<-[likes:Likes]-(user:User) 
WHERE likes.created_on > x-days-ago
WITH me, msg, user, likes.created_on as created_on
ORDER BY created_on LIMIT 25
WITH me, collect(distinct {user:user, created_on:created_on}) as activities
OPTIONAL MATCH (me)<-[mentions:Mentions]-(msg:Message)-[:Owner]->(user:User) 
WITH me, msg, user, mentions.created_on as created_on, activities
ORDER BY created_on LIMIT 25
WITH me, activities + collect(distinct {user:user, created_on:created_on}) as activities
OPTIONAL MATCH (me)<-[follows:Follows]-(user:User) 
WITH me, msg, user, follows.created_on as created_on, activities
ORDER BY created_on LIMIT 25
UNWIND (activities + collect(distinct {user:user, created_on:created_on})) as activity
RETURN activity
ORDER BY activity.created_on LIMIT 25

Answer 2

你可以使用联合http://neo4j.com/docs/stable/query-union.html 这样你就得到了所有的结果