Rails - Aug 2007 - easy way to render a tree

Hello list,

I''m trying to render a tree using the following helper function (added
it to
ApplicationHelper):

def display_tree_recursive(tree, parent_id)
  ret = "<ul>"
  tree.each do |node|
    if node.parent_id == parent_id
      ret += "<li style=\"list-style:none;\">"
      ret += yield node
      ret += display_tree_recursive(tree, node.id) { |n| yield n }
      ret += "</li>"
    end
  end
  ret += "</ul>"
end

In my view, I''ve got the following Erb code:

 <%    display_tree_recursive(@categories,0) do |node|

        if node.parent_id == 0

           "<b>" + node.name + "</b>"
        else

            pos = 20 if node.parent_id == 0;
            pos = node.parent_id+20 if node.parent_id != 0;
             "<span
style=\"position:relative;right:#{pos}p\">#{node.name
}</span>"
        end

    end

   %>


Of course I''m going nowhere with this logic and that''s why
I''d like to know
of an easy and effective way to render a tree hierachically, in a way that a
child get more to the right than its parent. Is there any helper available
for this?

Thanks.

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Hi Marcelo

def list_tree(tree, level = 0, &block)
  content = tree.children.inject '''' do |mem, node|
    mem + block[node, level] + list_tree(node, level + 1, &block)
  end

  content_tag :ul, content_tag(:li, content),
    :class => "#{tree.class.name.tableize}_#{level}"
end

<%
list_tree @tree do |node, level|
  content_tag("h#{level}", node.name) + content_tag(:p, node.text)
end

%>

Regards
Florian

PS: untested...

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Thanks Florian... actually I''ve used the following code and it is
working
nicely, I will try you code though and let you know how it worked :)

       def display_tree_recursive(tree, parent_id)
  ret = "<ul>"
  tree.each do |node|
    if node.parent_id == parent_id




      if (node.parent_id == 0)
        classe = "root_node"
      else
        classe = "sub_node"
      end
      ret += "<li class=\"#{classe}\">"
      ret += "<span class=\"#{classe}\">"

      ret +=  link_to node.name, {:controller => "documents",
:action =>
"list", :id => node.id}
      ret += display_tree_recursive(tree, node.id) { |n| yield n }
      ret += "</span>"
      ret += "</li>"
    end
  end
  ret += "</ul>"
end

The CSS'' classes used:

.root_node {

    font-size:14px;
    font-weight:bolder;
    list-style:none;
}

.sub_node {

    font-size:14px;
    text-indent:0px;
    left:15px;
    font-weight:normal;
    position:relative;
    list-style-position:inherit;

}

Thanks!

Marcelo.

On 8/29/07, Florian Aßmann <florian.assmann-htSm2yLGOjU@public.gmane.org>
wrote:
>
>
> Hi Marcelo
>
> def list_tree(tree, level = 0, &block)
>   content = tree.children.inject '''' do |mem, node|
>     mem + block[node, level] + list_tree(node, level + 1, &block)
>   end
>
>   content_tag :ul, content_tag(:li, content),
>     :class => "#{tree.class.name.tableize}_#{level}"
> end
>
> <%>
> list_tree @tree do |node, level|
>   content_tag("h#{level}", node.name) + content_tag(:p,
node.text)
> end
>
> %>
>
> Regards
> Florian
>
> PS: untested...
>
> >
>
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