Question

I am trying to write a Rails helper method to convert a nested hash into a nested HTML list.

For example:

{
  :parent => "foo",
  :children => [
    {
      :parent => "bar",
      :children => [
        {
          :parent => "baz",
          :children => []
        }
      ]
    }
  ]
}

should become:

<ul>
  <li>foo</li>
  <ul>
    <li>bar</li>
    <ul>
      <li>baz</li>
    </ul>
  </ul>
</ul>

The hash may have any number of levels, and any number of parents per level.

What is the best way to achieve this please?

Answer 1

You can make a recursive method to render to hash to a nested set of lists. Place this in your relevant helper:

def hash_list_tag(hash)
  html = content_tag(:ul) {
    ul_contents = ""
    ul_contents << content_tag(:li, hash[:parent])
    hash[:children].each do |child|
      ul_contents << hash_list_tag(child)
    end

    ul_contents.html_safe
  }.html_safe
end