过滤与某个节点没有关系的Neo4j节点

Question

I want to find all Foos that are not yet associated with my Bar. I use neo4j.rb (4.1.2) and Rails (4.2). The code I use now, that produces the right output but feels unoptimal is:

@foos = Foo.all.find_all do |foo|
  foo.bars.rels_to(current_bar).count == 0
end 

Is there a better way of doing this with Cypher?

Answer 1

Here is one way to do this in Cypher. I assume you are only interested in direct relationships, and that Bar nodes are identified by an id property.

MATCH (b:Bar), (f:Foo)
WHERE b.id = 123 AND NOT (b)--(f)
RETURN b, COLLECT(f);