Model Configurations

A model configuration enables OData service authors to apply model setups that are specific to a service API version. The VersionedODataModelBuilder will call Apply for each discovered API version with the current ODataModelBuilder.

public interface IModelConfiguration
{
   void Apply( ODataModelBuilder builder, ApiVersion apiVersion, string routePrefix );
}

The implementation of a model configuration can provide all variations of a model or they can be spit across multiple implementations. The applied model does not have to be same across API versions.

Consider the following model:

public class Person
{
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Email { get; set; }
    public string Phone { get; set; }
}

Let us assume that the OData service for this model has three versions: 1.0, 2.0, and 3.0. In API version 1.0, a person had the properties Id, FirstName, and LastName. In API version 2.0 we introduced the Email property. In API version 3.0 we introduced the Phone property. If we implement the entire model configuration in a single class, it might look like:

public class PersonModelConfiguration : IModelConfiguration
{
    private void ConfigureV1( ODataModelBuilder builder ) =>
        ConfigureCurrent( builder ).Ignore( p => p.Email ).Ignore( p => p.Phone );

    private void ConfigureV2( ODataModelBuilder builder ) =>
        ConfigureCurrent( builder ).Ignore( p => p.Phone );

    private EntityTypeConfiguration<Person> ConfigureCurrent( ODataModelBuilder builder )
    {
        var person = builder.EntitySet<Person>( "People" ).EntityType;
        person.HasKey( p => p.Id );
        return person;
    }

    public void Apply( ODataModelBuilder builder, ApiVersion apiVersion, string routePrefix )
    {
        switch ( apiVersion.MajorVersion )
        {
            case 1:
                ConfigureV1( builder );
                break;
            case 2:
                ConfigureV2( builder );
                break;
            default:
                ConfigureCurrent( builder );
                break;
        }
    }
}

Even through we have a single Person class, the EDM associated with the service API version will render the model according the requested API version.

~/people(1)?api-version=1.0

{
   "id": 1,
   "firstName": "John",
   "lastName": "Doe"
}

~/people(1)?api-version=2.0

{
   "id": 1,
   "firstName": "John",
   "lastName": "Doe",
   "email": "john.doe@somewhere.com"
}

~/people(1)?api-version=3.0

{
   "id": 1,
   "firstName": "John",
   "lastName": "Doe",
   "email": "john.doe@somewhere.com",
   "phone": "555-555-5555"
}