ruby-on-rails - Neo4j.rb 对两种关系分别查询进出

Question

这是我的 Neo4j 模型

class User
 include Neo4j::ActiveNode
 has_many :both, :followers, type: :following, model_class: 'User'
end

user1 有 2 个输出和 1 个输入，如下所示

用户 1 ---> 用户 2

用户 1 ---> 用户 3

用户 1 <--- 用户 3

如果我像下面这样查询它会返回输入/输出

user1.followers.count #returns 3

我想分别查询一个用户的进出

我怎么能用 Neo4j.rb 做到这一点..

提前致谢。

Answer 1

由于关联规定了匹配 Cypher 的编写方式，因此在调用该方法以更改其行为时，您无法覆盖该方法。解决方案是再创建两个关联。

class User
  include Neo4j::ActiveNode
  has_many :both, :followers, type: :following, model_class: 'User'
  has_many :out,  :following, type: :following, model_class: 'User'
  has_many :in,   :followed_by, type: :following, model_class: 'User'
  end
end

# Or, to make it feel more Ruby...

class User
  include Neo4j::ActiveNode
  [[:both, :followers], [:out, :following], [:in, :followed_by]].each do |dir, assoc|
    has_many dir, assoc, type: :following, model_class: 'User'
  end
end


2.2.0 :008 >   User.followers.to_cypher
 => "MATCH (node2:`User`), (result_followers:`User`), node2-[rel1:`following`]-(result_followers:`User`)" 
2.2.0 :009 > User.following.to_cypher
 => "MATCH (node2:`User`), (result_following:`User`), node2-[rel1:`following`]->(result_following:`User`)" 
2.2.0 :010 > User.followed_by.to_cypher
 => "MATCH (node2:`User`), (result_followed_by:`User`), node2<-[rel1:`following`]-(result_followed_by:`User`)"