Why does my recursive method from helper not return every value?

问题

I want to display a tree of categories managed with the gem ancestry.

I would like to use a helper which will recursively go through the tree and return the categories one by one, for the moment without html tags or content.

module CategoriesHelper
  def display_tree(category)
    if category.has_children? 
      category.children.each do |sub_category|
        display_tree(sub_category)
        puts(sub_category.name) # to check if it goes here
      end
    end
    category.name
  end
end

The category argument is one of the root categories.

What should it return?

In the web page: It displays only the root level category Sport Beauty Automobile
In the console: Men Indoor Women Children Water sport Garage

If get them, then it means that the recursion works, but it does not. Why does it return only the first iteration?

Also I would like to get them in the following order:

root/child/child-of-child

but if I want to return category.name, it should be in the last position.

Could you please give me your comments?

PS: I just found out (during adding tags) that I was using the word "recursivity" all along my searches but it doesn't exist, even if many people are using it on stackOveflow ;o) -> "recursion", but still I'm stuck

** EDIT **

Now I use this code:

            module CategoriesHelper

              def display_tree(category)
                tree = "<div class =\"nested_category\">#{category.name}" 
                if category.has_children? 
                  category.children.each do |sub_category|
                    tree += "#{display_tree(sub_category)}"
                  end
                end
                tree += "</div>"
              end
            end

which gives me:

        <div class ="nested_category">Sport
            <div class ="nested_category">Men</div>
            <div class ="nested_category">Women
                <div class ="nested_category">Indoor</div>
            </div>
            <div class ="nested_category">Children</div>
            <div class ="nested_category">Water sport</div>
        </div> 
        <div class ="nested_category">Beauty</div> 
        <div class ="nested_category">Automobile
            <div class ="nested_category">Garage</div>
        </div>

But that html is not interpreted and the same code is shown in the displayed webpage. I mean that I see

I probably missed something... maybe knowledge oO

Thx

回答1:

The mothod you are using will return just one value (the fist call to category.name actually) About the console, you are getting the puts that you have inside the loop (that is not the return value of the method).

Try this and let me know if there's still something not clear enough:

module CategoriesHelper

  def display_tree(category)
    tree = category.name 
    if category.has_children? 
      category.children.each do |sub_category|
        tree += "/#{display_tree(sub_category)}"
      end
    end
    tree
  end

end

回答2:

        module CategoriesHelper

          def display_tree(category)
            tree = "<div class =\"nested_category\">#{category.name}" 
            if category.has_children? 
              category.children.each do |sub_category|
                tree += "#{display_tree(sub_category)}"
              end
            end
            tree += "</div>"
            tree.html_safe #That was missing to interprete the html returned...
          end
        end

I answer for my last edit question. I had to add this line :