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A Implementation - A Component Factory that Caches

A DD4T ComponentFactory is in charge of retrieving or searching for IComponent models by using either serving them from local cache or delegating the call to a ComponentProvider that uses the Tridion Broker API to look things up in the Content Delivery database.

When retrieving Component models, the ComponentFactory uses a couple of methods that take as parameters the TcmUri of the Component and a Component Template TcmUri.

    IComponent GetComponent(string componentUri, string templateUri = "");
    bool TryGetComponent(string componentUri, out IComponent component, string templateUri = "");

The default ComponentFactory from DD4T .net v1.31 has been written in a relaxed fashion, and don't enforce a mandatory Component Template TcmUri. If a lazy developer chooses not to pass a templateUri, the code still works. However, the call to the Content Delivery database is not cached. This results in performance degradation when the internal DD4T cache is expired, and a new call to a previously retrieved Component is made. The request will make all its way to the database.

This issue can easily be prevented by passing a Component Template TcmUri to these two methods. However, developers being lazy people, I want to enforce the second parameter to be passed and to have a valid TcmUri in it.

As such, I created my own CachingComponentFactory class as a specialization of the DD4T default ComponentFactory, where I overrode the two methods:

    public class CachingComponentFactory : ComponentFactory, IComponentFactory
        public new IComponent GetComponent(string componentUri, string templateUri)
            if (!UriHelper.IsValidTcmUri(templateUri))
                throw new ComponentNotFoundException();

            return base.GetComponent(componentUri, templateUri);

        public new bool TryGetComponent(string componentUri, out IComponent component, string templateUri)
            if (!UriHelper.IsValidTcmUri(templateUri))
                component = null;
                return false;

            return base.TryGetComponent(componentUri, out component, templateUri);

The code is very straight forward and expects the second TcmUri parameter to be passed and to be a valid TcmUri. Anything else results is a ComponentNotFoundException.

The only thing left to do is to wire up my CachingComponentFactory in Ninject so that it is used every time an IComponentFactory instance is requested.



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