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A DD4T.net Implementation - Strong Typed Models

After a year-long project of DD4T Java, where we developed version 2.0 of the framework, it is now time to do it all over again, this time in .NET. This is the first of a series of posts dedicated to implementing DD4T .NET.

DD4T Java v2.0 offers a few goodies that are currently not available in DD4T .NET (v1.31). For example strong type model support or a Model Factory.

I'm going to start with presenting a flavor of strong type models that can be used in your project. I initially went on and called them ViewModels, but in fact they are more like domain models. They are used as building blocks for creating the actual view models that the Views use.

As such, the domain models represent a one to one mapping of the Schema and the properties inside each model class represent fields in the Schema. They are strong typed because they follow the same types declared in the fields (numeric, text, Component Link, Keyword, etc). Multi-valued fields are represented as IList generics.

Let's take the following example and explain it in detail.

    public class Device : BaseModel
    {
        public Banner Banner { get; set; }
        public IList<EmbeddedParagraph> Body { get; set; }
        public IList<BaseModel> RelatedItems { get; set; }
        public DeviceMetadata Metadata { get; set; }

        public class DeviceMetadata
        {
            public double LegacyId { get; set; }
            public string ShortTitle { get; set; }
            public IList<IKeyword> Products { get; set; }
            public DateTime UpdateDate { get; set; }
        }

        public Device(IComponent component) : base(component) { }
    }


The Device model represents a direct mapping of the Schema Device and each property inside the model represents a field in the Schema. The simple types are Text (string), Numeric (double), Date (DateTime). Embedded fields, Component link fields and Multimedia links have their own domain model types, defined in their respective classes.

Property Banner represents a single-value Component link to another model based on Schema Banner. However, property RelatedItems is a multi-value Component link that in the Schema it is configured to allow more than one possible type. Hence, the type of the IList generic is BaseModel, which simply represents the base class each domain model inherits from. More about the BaseModel, below.

Text fields in a Schema that represent Keywords in a Category are mapped to DD4T.ContentModel.IKeyword properties in the model.

I chose to implement metadata fields as properties of an inner class nested inside each domain model (i.e. DeviceMetadata in the example above).

Embedded fields (e.g. Body) have their own domain model class, only they don't represent a Component like the Device model does. They lack the constructor that take an IComponent parameter as well. Below is such a embedded domain class:

    public class EmbeddedParagraph : BaseModel
    {
        public string Heading { get; set; }
        public string Body { get; set; }
    }


Multimedia Schemas map to similar domain models, but with a little twist -- they don't contain any fields/properties; they only contain metadata fields/properties and a DD4T.ContentModel.IMultimedia property to hold the multimedia metadata itself.

    public class Image : BaseModel
    {
        public IMultimedia Multimedia { get; set; }
        public ImageMetadata Metadata { get; set; }

        public class ImageMetadata
        {
            public string AltText { get; set; }
            public string TitleText { get; set; }
        }

        public Image(IComponent component) : base(component) { }
    }


The BaseModel class declares a few base properties, such as Id, Schema, or model Title. It also handles some basic Component Link resolving (resolving the URL of a Page where this domain model appears on -- but more about that in another post).

    public class BaseModel : IComparable<BaseModel>
    {
        public string Id { get; set; }
        public ISchema Schema { get; set; }
        public string Title { get; set; }

        public BaseModel() { }

        public BaseModel(IComponent component)
        {
            Id = component.Id;
            Schema = component.Schema;
            Title = component.Title;
        }
    }



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