ruby-on-rails - 为什么我的递归函数不起作用？

Question

我有一个基于 neo4j.rb 的 rails 模型（评论）。我的简单方法应该返回孩子的数量，而是返回 LocalJumpError（没有给出块（yield））。我究竟做错了什么？

has_many :both, :children, model_class: Comment, unique: true

def get_number_of_replies
    if children.count == 0
      0
    else
      children.count + children.each.get_number_of_replies
    end
end

Answer 1

我认为

children.count + children.each.get_number_of_replies

应该

children.count + children.collect(&:get_number_of_replies).sum

正如您的错误所示，each需要一个块。

Answer 2

您需要遍历每个孩子以获得所需的结果：

def get_number_of_replies
  if children.count == 0
    0
  else
    total = 0
    children.each do |c|
      total += children.get_number_of_replies
    end
    children.count + total
  end
end

Answer 3

Brad Werth 写的是正确的。问题还在于，当子连接双向工作时，我正在创建一个无限循环。所以这里是解决方案：

  has_many :out, :children, model_class: Comment, unique: true
  has_one :in, :child_of, model_class: Comment, unique: true

  def get_number_of_replies
    result = 0
    unless children.count() == 0
      result += children.count
      children.each do |child|
        result += child.get_number_of_replies
      end
    end
    result
  end