Rendering a view of hierarchical lists with unknown/unlimited nesting - ruby-on-rails

Question

The following pattern is a set of lists nested within other list items.
<ul id="nestedlist">
<li> 1
<ul>
<li> 1.1
<ul>
<li> 1.1.1</li>
<li> 1.1.2</li>
<li> 1.1.3</li>
</ul>
</li>
<li class="connect"> 1.2
<ul>
<li> 1.2.1</li>
<li> 1.2.2</li>
<li> 1.2.3</li>
<li> 1.2.4</li>
<li> 1.2.5
<ul>
<li> 1.2.5.1</li>
<li> 1.2.5.2
<ul>
<li> 1.2.5.2.1</li>
<li> 1.2.5.2.2</li>
</ul>
</li>
<li> 1.2.5.3</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
The model Node
belongs_to :parentnode
has_many :children_nodes, foreign_key: :parentnode_id, class_name: 'Parentnode'
Thus an unlimited number of levels can be defined in a hierarchy.
The view rendering is essential a pattern where each node can become a parentnode
Parentnode.children_nodes.each_with_index do |node, index|
node.name
**parent_indicies.(index + 1)**
end
How can this be rendered in a rails view to represent each node level and its nesting level when the nesting levels are not known beforehand?

Answer 1

You can use rails helper methods to generate rails view.
Example:
content_tag(:ul) do
(1..10).each do |node|
concat content_tag(:li, node)
end
end
And the logic would be to use recursion:
def generate_list(node, level)
return if node == nil
#put logic of generating ul li here.
#add ul if node.children_nodes.present?
#else add li.
node.children_nodes.each_with_index |node, index|
generate_list(node, "#{level}.#{index+1}"
end
end
This is just the base logic. I hope you can do the rest of the part. If you still face difficulty just let me know.
Updated with below working code to generate html:
class Node
attr_accessor :val, :children_nodes
def initialize(value)
self.val = value
self.children_nodes = []
end
end
p1 = Node.new("P")
n1 = Node.new("1")
n2 = Node.new("2")
p1.children_nodes.push(n1)
p1.children_nodes.push(n2)
def generate_list(node, level, final_str)
return if node == nil
if node.children_nodes.size > 0
final_str << "<li> #{node.val}"
final_str << "<ul> "
else
final_str << "<li> #{node.val} </li>"
end
node.children_nodes.each_with_index do |n, index|
generate_list(n, "#{level}.#{index+1}", final_str)
end
if node.children_nodes.size > 0
final_str << "</ul> "
final_str << "</li>"
end
end
def generate(node)
final_str = ""
final_str << "<ul>"
generate_list(node, 1, final_str)
final_str << "</ul>"
final_str
end
puts generate(p1)