Skip to main content

A DD4T.net Implementation - Taxonomy Factory

I have noticed that in all my recent projects, there is a strong need for an easy and well performing way of handling taxonomies. Functionality ranges from being able to read a Keyword in a taxonomy, to traverse the child/parent relationships, to read metadata on a Keyword and also to read related Components tagged against a Keyword.

In order to provide these features, I implemented a DD4T factory that deals with Tridion taxonomies. Namely, I created the ITaxonomyFactory that defines certain method signatures. I'm using Ninject to bind the interface to an actual implementing class, so using this in DD4T context is trivial.

public interface ITaxonomyFactory
{
    MyKeyword GetTaxonomy(string taxonomyXmlNameOrUri);
    MyKeyword GetKeywordByUri(MyKeyword root, string uri);
}

The factory class uses the TaxonomyFactory and TaxonomyRelationManager to interact with the data published to the Content Delivery database.

Method GetTaxonomy takes either a Taxonomy XML name, as defined in Tridion CMS (which is resolved using the labels mechanism described in post Everything's a Label) or TcmUri of a Tridion Category.

The method uses the CacheWrapper described in post A Simple TTL Cache, in order to store either a root Keyword object or a null value for a given amount of time.

The returned value, MyKeyword, is a specialization object of DD4T.ContentModel.IKeyword, which will be described in a follow-up post.

public class MyTaxonomyFactory : ITaxonomyFactory
{
    [Inject]
    public virtual ICacheWrapper CacheWrapper { get; set; }

    private TaxonomyFactory taxonomyFactory;
    private TaxonomyRelationManager manager;

    public MyTaxonomyFactory()
    {
        taxonomyFactory = new TaxonomyFactory();
        manager = new TaxonomyRelationManager();
    }

    public MyKeyword GetTaxonomy(string taxonomyXmlNameOrUri)
    {
        MyKeyword result;
        object cacheElement;
        string taxonomyUri = DD4TResourceProvider.GetTaxonomyLabel(taxonomyXmlNameOrUri);
        string key = "category" + taxonomyUri;

        if (CacheWrapper.TryGet(key, out cacheElement))
        {
            result = cacheElement as MyKeyword;
        }
        else
        {
            tridion.Keyword tridionKeyword = taxonomyFactory.GetTaxonomyKeywords(taxonomyUri);
            if (tridionKeyword == null)
            {
                result = null;
                CacheWrapper.Insert(key, false, 1);
            }
            else
            {
                TaxonomyConverter taxonomyConverter = new TaxonomyConverter();
                result = taxonomyConverter.ConvertToDD4T(tridionKeyword);
                CacheWrapper.Insert(key, result, 60);
            }
        }

        return result;
    }

Method GetKeywordByUri is a simple traversal method starting from a keyword in the taxonomy and searching depth-first for a keyword whose TcmUri matches a TcmUri we look for. The implementation makes use of a fancy delegate method, through which we can easily supply different comparison logic. The KeywordComparer returns a boolean result from comparing two Keywords. In the GetKeywordByUri method, we simply provide a comparer that only checks the keywords TcmUri. This mechanism is very flexible and easy to extend for other types of comparisons, for example by keyword title, key or even some custom meta field.

private delegate bool KeywordComparer(MyKeyword keyword);

public MyKeyword GetKeywordByUri(MyKeyword root, string uri)
{
    return SearchKeyword(root, delegate(MyKeyword keyword)
    {
        return keyword != null && keyword.Id.Equals(uri);
    });
}

private MyKeyword SearchKeyword(MyKeyword root, KeywordComparer keywordComparer)
{
    if (keywordComparer(root))
    {
        return root;
    }

    foreach (MyKeyword childKeyword in root.ChildKeywords)
    {
        MyKeyword result = SearchKeyword(childKeyword, keywordComparer);
        if (result != null)
        {
            return result;
        }
    }

    return null;
}

As an example, the following code snippet reads a taxonomy and a given keyword in it:

    ITaxonomyFactory factory = 
            DependencyResolver.Current.GetService<ITaxonomyFactory>();
    MyKeyword root = factory.GetTaxonomy("Product-Catalog");
    MyKeyword product = factory.GetKeywordByUri(root, "tcm:123-456-1024");


Comments

Popular posts from this blog

Toolkit - Dynamic Content Queries

This post if part of a series about the  File System Toolkit  - a custom content delivery API for SDL Tridion. This post presents the Dynamic Content Query capability. The requirements for the Toolkit API are that it should be able to provide CustomMeta queries, pagination, and sorting -- all on the file system, without the use third party tools (database, search engines, indexers, etc). Therefore I had to implement a simple database engine and indexer -- which is described in more detail in post Writing My Own Database Engine . The querying logic does not make use of cache. This means the query logic is executed every time. When models are requested, the models are however retrieved using the ModelFactory and those are cached. Query Class This is the main class for dynamic content queries. It is the entry point into the execution logic of a query. The class takes as parameter a Criterion (presented below) which triggers the execution of query in all sub-criteria of a Criterio

A DD4T.net Implementation - Custom Binary Publisher

The default way to publish binaries in DD4T is implemented in class DD4T.Templates.Base.Utils.BinaryPublisher and uses method RenderedItem.AddBinary(Component) . This produces binaries that have their TCM URI as suffix in their filename. In my recent project, we had a requirement that binary file names should be clean (without the TCM URI suffix). Therefore, it was time to modify the way DD4T was publishing binaries. The method in charge with publishing binaries is called PublishItem and is defined in class BinaryPublisher . I therefore extended the BinaryPublisher and overrode method PublishItem. public class CustomBinaryPublisher : BinaryPublisher { private Template currentTemplate; private TcmUri structureGroupUri; In its simplest form, method PublishItem just takes the item and passes it to the AddBinary. In order to accomplish the requirement, we must specify a filename while publishing. This is the file name part of the binary path of Component.BinaryConten

Scaling Policies

This post is part of a bigger topic Autoscaling Publishers in AWS . In a previous post we talked about the Auto Scaling Groups , but we didn't go into details on the Scaling Policies. This is the purpose of this blog post. As defined earlier, the Scaling Policies define the rules according to which the group size is increased or decreased. These rules are based on instance metrics (e.g. CPU), CloudWatch custom metrics, or even CloudWatch alarms and their states and values. We defined a Scaling Policy with Steps, called 'increase_group_size', which is triggered first by the CloudWatch Alarm 'Publish_Alarm' defined earlier. Also depending on the size of the monitored CloudWatch custom metric 'Waiting for Publish', the Scaling Policy with Steps can add a difference number of instances to the group. The scaling policy sets the number of instances in group to 1 if there are between 1000 and 2000 items Waiting for Publish in the queue. It also sets the