CODEWITHSUNDEEP
ruby-on-railsruby
Marcin Doliwa
Marcin Doliwa

Reputation: 3659

Simple recursive method in model

I'm trying to write very simple recursive method, but can't make it work. I have simple comments hierarchy with ids like here:

1--
   2--
      4--
   3--
      5--

Now I want to save their ids in array (tree order) [0]=1, [1]=2, [2]=4, [3]=3, [4]=5

I start building this array in Entry model with

def comment_tree
  comment = self.comments.find(1) #it's temporary, just to check if it works
  return recur(comment,0)
end

private
def recur(comment,i)
  @tree[i]=comment.id #added attr_accessible :@tree
  if comment.children.any?
    comment.children.each {|c| recur(c,i+1)}
  else
    return
  end
  @tree
end

This doesn't work, as block runs twice the same counter argument recur(4,2) and recur(3,2). I need something like global $i to keep this arras index, but I'm sure there must be better way of doing it. The same is with @tree, do I really have to add new variable to model just to use it as a return parameter from recur method? I won't use it in any other place.

Upvotes: 1

Views: 373

Answers (1)

Matt
Matt

Reputation: 5398

How about this:

def comment_tree
  comment = self.comments.find(1)
  tree = []
  recur(comment, tree)
  tree
end

private
def recur(comment, acc)
  acc << comment.id
  comment.children.each {|c| recur(c, acc) }
end

Upvotes: 2

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