Cypher：我可以返回收藏集或类似收藏吗？

Question

I currently have the following cypher to return a list of Users, with the Roles they are assigned and the Application that the Role is for.

MATCH (u:User)-[:HAS_ROLE]->(r:Role)-[:ROLE_OF]->(a:App)
RETURN u as User, COLLECT([r, a]) as Roles

This returns a User and a collection of their roles and apps, but the collection is simply [roleA, appA, roleB, appA, roleC, appB...].

Is there any way to return something like [[roleA, appA], [roleB, appA], [roleC, appB]...] as processing this list on the assumption that it is role, app, role, app does not seem like good practice to me.

I can return the roles and apps as separate collections, but then I do not know which app each role is assigned to. The only other way I can think of doing this is to perform multiple queries, which I do not want to do.

I am sure there must be a better way, maybe using WITH, but I am new to Cypher.

Many thanks for your help :)

Answer 1

You query appears to be working for me.

http://console.neo4j.org/r/4zp6uv

The output is:

+--------------------------------------------------------------------------------------------------------+
| User               | Roles                                                                             |
+--------------------------------------------------------------------------------------------------------+
| Node[5]{name:"u1"} | [[Node[4]{name:"r1"},Node[2]{name:"a1"}],[Node[3]{name:"r2"},Node[1]{name:"a2"}]] |
+--------------------------------------------------------------------------------------------------------+
1 row
14 ms

If you are still having some issues for some reason or another you could try modifying the query slightly just to break it up.

MATCH (u:User)-[:HAS_ROLE]->(r:Role)-[:ROLE_OF]->(a:App)
WITH u, [r, a] as tuple
RETURN u as User, COLLECT(tuple) as Roles