Neo4j Cypher version 1.8 : Probable bug with relat

问题:

http://console.neo4j.org/r/yx62bk

In the graph above, the query

start n=node(7,8,9) 
match n-[objectScore:score]->o-[:object_of_destination]->d<-[:destination_score]-n, 
o-[:instance_of]->ot, o-[:date]->oDate, d-[:date]->dDate where ot.name='HOTEL'  
return n, o, objectScore,  d;

returns o as null.

Change the query to remove relationship identifier - objectScore

start n=node(7,8,9) 
match n-[:score]->o-[:object_of_destination]->d<-[:destination_score]-n,
o-[:instance_of]->ot, o-[:date]->oDate, d-[:date]->dDate where ot.name='HOTEL'  
return n, o, objectScore,  d;

and the output returns o node correctly.

For my scenario I need both of them. Not sure How to do that? Any suggestions on this.

回答1:

Nice find. We track Cypher issues on github, so I've opened an issue about it there: https://github.com/neo4j/community/issues/837

Thanks so much for reporting it!

Edit: I've found the problem. A simple workaround is to, ironically, introduce an optional relationship. The problem is located in one of the matchers Cypher can use, and by marking a piece of your pattern as optional, you force Cypher to use a different matcher. If you want to

So, change your MATCH to this:

match n-[objectScore:score]->o-[:object_of_destination]->d<-[:destination_score]-n, 
      o-[:instance_of]->ot, 
      o-[:date]->oDate, 
      d-[?:date]->dDate 

A real fix is in the works.