My name
is
Jon Skeet

Recursive method wont loop childs children

I´m trying to create a recursive method to create a menu. The menu I want to achieve displays the childrens children and so on. I´ve debugged the code and it goes all the way down to the "youngest child".

public string GetMenu(Node currentPage)
    {
        StringWriter stringWriter = new StringWriter();
        using (HtmlTextWriter writer = new HtmlTextWriter(stringWriter))
        {

        foreach (var item in currentPage.ChildrenAsList)
        {
            writer.RenderBeginTag(HtmlTextWriterTag.Li);
            writer.AddAttribute(HtmlTextWriterAttribute.Href, item.Url);
            writer.RenderBeginTag(HtmlTextWriterTag.A);
            writer.Write(item.Name);


            if (item.ChildrenAsList.Any())
            {
                writer.RenderBeginTag(HtmlTextWriterTag.Ul);
                GetMenu(new Node(item.Id));
                writer.RenderEndTag();
            }
            writer.RenderEndTag();
            writer.RenderEndTag();
        }
    }
    return stringWriter.ToString();
}

This method give the output:

<ul class="nav nav-sidebar">

    <li>
    <a href="/artikelsida001/">Artikelsida001
    <ul>

    </ul>
    </a></li>
    <li><a href="/patrikartikelsida/">PatrikArtikelsida
    <ul>

    </ul>
    </a></li>
    <li><a href="/en-testsida/">En testsida</a></li>
    </ul>

Each time you call GetMenu, you're creating a new StringWriter - but you're ignoring the return value from your recursive calls. The simplest fix would probably be to change it to:

public string GetMenu(Node currentPage)
{
    var stringWriter = new StringWriter();
    using (var htmlWriter = new HtmlTextWriter(stringWriter))
    {
        RenderMenu(currentPage, writer);
    }
    return stringWriter.ToString();
}

private void RenderMenu(Node node, HtmlTextWriter writer)
{
    // Mostly copied from the code in the question...
    foreach (var item in currentPage.ChildrenAsList)
    {
        writer.RenderBeginTag(HtmlTextWriterTag.Li);
        writer.AddAttribute(HtmlTextWriterAttribute.Href, item.Url);
        writer.RenderBeginTag(HtmlTextWriterTag.A);
        writer.Write(item.Name);

        if (item.ChildrenAsList.Any())
        {
            writer.RenderBeginTag(HtmlTextWriterTag.Ul);
            // Note the change here
            RenderMenu(new Node(item.Id), writer));
            writer.RenderEndTag();
        }
        writer.RenderEndTag();
        writer.RenderEndTag();
    }
}

Note how the recursion now calls RenderMenu with the same writer.

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