Custom navigation provider in SharePoint 2013

SharePoint 2013 has many options for configuration of Global Navigation, Current Navigation and so forth. Navigation can be configured to use site hierarchy or terms store or inherit these settings. Navigation data is made available to controls in the master page via Navigation Providers. SharePoint 2013 has following OOB providers available to use as datasource.

        SPNavigationProvider

        SPSiteMapProvider

        SPContentMapProvider

        SPXmlContentMapProvider

        AdministrationQuickLaunchProvider

        SharedServicesQuickLaunchProvider

        GlobalNavSiteMapProvider

        CombinedNavSiteMapProvider

        CurrentNavSiteMapProvider

        CurrentNavSiteMapProviderNoEncode

        GlobalNavigation

        CurrentNavigation

        SiteDirectoryCategoryProvider

        MySitePersonalQuickLaunchProvider

        MySiteHostTopNavigationProvider

        GlobalNavigationSwitchableProvider

        CurrentNavigationSwitchableProvider

        GlobalNavigationTaxonomyProvider

        CurrentNavigationTaxonomyProvider

        MySiteMapProvider

        MySiteLeftNavProvider

        MySiteDocumentStaticProvider

        MySiteSitesPageStaticProvider

        MySiteSubNavProvider

        EduTopNavProvider

        MySiteHostQuickLaunchProvider

        QuickLaunchSiteMap

Despite all these options being available, at times there is a need to have a custom navigation provider which extends/modifies behavior of OOB navigation providers. I found an excellent post here which describes how such a control can be developed.

public class CustomNavProvider : SiteMapProvider
{
    private const string PROVIDERNAME = "GlobalNavigationTaxonomyProvider";

    public override SiteMapNode RootNode
    {
        get
        {
            return SiteMap.Providers[PROVIDERNAME].RootNode;
        }
    }

    public override SiteMapNode CurrentNode
    {
        get
        {
            return SiteMap.Providers[PROVIDERNAME].CurrentNode;
        }
    }

    public override SiteMapNodeCollection GetChildNodes(SiteMapNode parent)
    {
        SiteMapNodeCollection childNodes = new SiteMapNodeCollection();
        if ((parent == null) || (parent.Key == null)) return childNodes;

        foreach (SiteMapNode tempNode in SiteMap.Providers[PROVIDERNAME].GetChildNodes(parent))
        {
            //do stuff with tempNode
            childNodes.Add(tempNode);
        }

        return childNodes;
    }

    public override SiteMapNode FindSiteMapNode(string rawUrl)
    {
        return SiteMap.Providers[PROVIDERNAME].FindSiteMapNode(rawUrl);
    }

    public override SiteMapNode GetParentNode(SiteMapNode node)
    {
        return SiteMap.Providers[PROVIDERNAME].GetParentNode(node);
    }
}