Indent every child of a depth first search (ruby on rails)? - ruby-on-rails

Question

I am new to rails, and I was wondering if there was a simple (or not simple) way to indent every child of a DPS?
I have a model called "Comment" that has_many :comments and belongs_to :comment. In my view I've implemented a DPS to display each comment and each comment on that comment, and each comment on that comment, etc.
My code looks like this:
<div class=feed>
<% #comments.each do |comment| %>
<% if comment.comment_id == nil # display all original comments %>
<!-- subject -->
<div class="subject">
<%= comment.subject %>:
</div>
<!-- create array of replies -->
<% replies = Array.new %>
<% replies.push(comment) %>
<% while replies.any? %>
<% reply = replies[0] %>
<% replies.delete_at(0) %>
<!--- name -->
<div class="comment">
<%= User.find(reply.user_id).name %>
<!-- comment -->
<%= reply.body %>
<% if user_signed_in? %>
<%= link_to "reply", new_comment_comment_path(reply.id) %>
<% end %>
</div>
<% reply.comments.each do |further_replies| %>
<% replies.push(further_replies) %>
<% end %>
<br>
<% end %>
<br>
<% end %>
<% end %>
</div>
where I push each comment onto "replies" and visit each reply one by one.
Is there a good way to indent each child comment?
Thanks!

Answer 1

You can use act_as_tree structure, in that case your model will be like -
class Comment
has_many :replies, class_name: 'Comment', foreign_key :comment_id
belongs_to :user
end
Your html code will be very simple in that case like
<div class=feed>
<% #comments.each do |comment| %>
<div class="subject">
<%= comment.subject %>:
</div>
<% comment.replies.each do |reply| %>
<div class="comment">
<%= reply.user..name %>
<%= reply.body %>
<% if user_signed_in? %>
<%= link_to "reply", new_comment_comment_path(reply.id) %>
<% end %>
</div>
<br>
<% end %>
<br>
<% end %>
</div>

Answer 2

I figured out a different approach that worked well. I implemented a recursive depth first search in "CommentsController" that returned a hash of { comments => amount_to_indent }, where comments are in the order that they were visited. In the view file iterated though the hash, using comment and amount_of_indent where appropriate.
class CommentsController < ApplicationController
def index
#comments = Comment.all
# depth first search
#visited = Hash.new
#comments.each do |comment|
if !comment.comment_id # has not parent comment
indent = 0
comment_array = DFS(comment, #visited, indent)
end
end
end
def DFS(comment, visited, indent)
visited[comment] = indent # add elements in order in which they are visited
comment.comments.each do |reply|
DFS(reply, visited, indent + 4)
end
visited
end
And in the view file:
<div class="feed">
<% #visited.each do |reply, indent| %>
<!-- display subject of all parent comments -->
<div class="subject">
<% if !reply.comment_id? %>
<%= reply.subject %>:
<% end %>
</div>
<!--- name and content -->
<div class="comment">
<!-- preceed comment with indent -->
<%= raw(('&nbsp') * indent) %>
<%= User.find(reply.user_id).name + ":" + reply.body %>
<% if user_signed_in? %>
<%= link_to "reply", new_comment_comment_path(reply.id) %>
<!--%= link_to 'delete', response, method: :delete, data: { confirm: 'Are you sure?' } %-->
<% end %>
</div>
<% end %>
</div>
If anyone runs into the same issue I did!