Neo4j：根据节点表示路径密码查询结果

Question

I have the following node structure Emp[e_id, e_name, e_bossid] . What is more I have a recursive query that exploit the database in recursive traversal on SELF relation e_bossid-[REPORTS_TO]->e_id

MATCH (e:Employee) WHERE NOT (e)-[:REPORTS_TO]->()
SET e:Root;

MATCH path = (b:Root)<-[:REPORTS_TO*]-(e:Employee)
RETURN path
limit 1000;

However the result is PATH. I would like to have result in form of NODES not the path. I tried to use the nodes(path) , but it gives me an error:

org.codehaus.jackson.map.JsonMappingException: Reference node not available (through reference chain: java.util.ArrayList[0]->java.util.HashMap["rel"]->java.util.HashMap["nodes(path)"]->java.util.ArrayList[0]->org.neo4j.rest.graphdb.entity.RestNode["restApi"]->org.neo4j.rest.graphdb.RestAPIFacade["direct"]->org.neo4j.rest.graphdb.ExecutingRestAPI["referenceNode"])

When I query without nodes(path) it seems to return only paths.

How this should be done on the ground of cypher query?

Answer 1

I'm not sure why you would want to get all possible paths in your organizational hierarchy. Maybe what you want to get is a set of paths from the leaves of the tree to the root of the tree, and to return each unique set as a row of nodes.

MATCH (b:Employee)
WHERE NOT (b)-[:REPORTS_TO]->()
MATCH (l:Employee)
WHERE NOT (l)<-[:REPORTS_TO]-()
MATCH p = shortestPath((b)<-[:REPORTS_TO*]-(l))
RETURN nodes(p) as reports

As far as your error goes, that looks like a bug, although I don't know what version of Neo4j you are using. In all likelihood, your query won't complete because your Root employees are still a member of the Employee label. Which means that this pattern: MATCH path = (b:Root)<-[:REPORTS_TO*]-(e:Employee) matches the Root employees on each side of the variable length traversal.

Give my query a try and let me know what happens.