A DD4T.net Implementation - Taxonomy Converter

In a previous post, I presented the Taxonomy Factory and a way of retrieving taxonomies and keywords from Tridion. One of the promises I made in there was to explain the conversion process from a Tridion Keyword to a specialized class MyKeyword, a subclass of DD4T.ContentModel.IKeyword.

The DD4T IKeyword class does not provide a way to navigate the taxonomy downwards -- it only provides a ParentKeywords property. Therefore, I created IMyKeyword:

public interface IMyKeyword : IKeyword
{
    IList<IMyKeyword> ChildKeywords { get; }
    IMyKeyword ParentKeyword { get; }
    new IList<IMyKeyword> ParentKeywords { get; }
}

Its accompanying implementation class is quite trivial:

using dd4t = DD4T.ContentModel;

public class MyKeyword : dd4t.Keyword, IMyKeyword
{
    private IList<IMyKeyword> _childKeywords = new List<IMyKeyword>();
    public IList<IMyKeyword> ChildKeywords
    {
        get { return _childKeywords; }
    }

    private IList<IMyKeyword> _parentKeywords = new List<IMyKeyword>();
    public IMyKeyword ParentKeyword
    {
        get { return _parentKeywords.FirstOrDefault(); }
    }
    public new IList<IMyKeyword> ParentKeywords
    {
        get { return _parentKeywords; }
    }
}

In order to convert a Tridion.ContentDelivery.Taxonomies.Keyword to MyKeyword, I'm using the following TaxonomyConverter class, which performs a recursive deep-copy of the given Tridion Keyword to a MyKeyword instance, by populating all properties and building the Parent/Child keyword sets.

using dd4t = DD4T.ContentModel;
using tridion = Tridion.ContentDelivery.Taxonomies;

public class TaxonomyConverter
{
    public IMyKeyword ConvertToDD4T(tridion.Keyword keyword)
    {
        string publicationUri = UriHelper.GetPublicationUri(keyword.KeywordUri);
        dd4t.Publication publication = BuildPublication(keyword, publicationUri);

        IMyKeyword result = new MyKeyword()
        {
            Description = keyword.KeywordDescription,
            Id = keyword.KeywordUri,
            Key = keyword.KeywordKey,
            MetadataFields = BuildMetadata(keyword.KeywordMeta),
            OwningPublication = publication,
            Path = BuildPath(keyword),
            Publication = publication,
            PublicationId = publicationUri,
            TaxonomyId = keyword.TaxonomyUri,
            Title = keyword.KeywordName
        };

        ConvertToDD4TList(result.ParentKeywords, keyword.ParentKeywords);
        ConvertToDD4TList(result.ChildKeywords, keyword.KeywordChildren);

        return result;
    }

    public void ConvertToDD4TList(IList<IMylKeyword> myKeywords, IList tridionKeywords)
    {
        if (tridionKeywords == null)
        {
            return;
        }

        foreach (tridion.Keyword tridionKeyword in tridionKeywords)
        {
            myKeywords.Add(ConvertToDD4T(tridionKeyword));
        }
    }

    private dd4t.FieldSet BuildMetadata(CustomMeta customMeta)
    {
        IDictionary nameValues = customMeta.NameValues;
        if (customMeta == null || nameValues.IsNullOrEmpty())
        {
            return null;
        }

        dd4t.FieldSet fieldSet = new dd4t.FieldSet();
        foreach (NameValuePair pair in nameValues.Values)
        {
            string name = pair.Name;
            switch (pair.ValueType)
            {
                case 2: // Date
                    fieldSet.Add(name, new dd4t.Field()
                    {
                        Name = name,
                        DateTimeValues = pair.MultipleValues.Cast<DateTime>().ToList()
                    });
                    break;

                case 3: // Numeric
                    fieldSet.Add(name, new dd4t.Field()
                    {
                        Name = name,
                        NumericValues = pair.MultipleValues.Cast<float>().Select(x => Convert.ToDouble(x.ToString())).ToList()
                    });
                    break;

                default: // String
                    fieldSet.Add(name, new dd4t.Field()
                    {
                        Name = name,
                        Values = pair.MultipleValues.Cast<string>().ToList()
                    });
                    break;
            }
        }

        return fieldSet;
    }
}