Define type inheritance

Applies To: # OData core lib v7 supported OData Core Lib V7

Type inheritance means defining a type by deriving from another type. EdmLib supports defining both derived entity types and derived complex types. Adding a derived entity (complex) type is almost identical to adding a normal entity (complex) type except that an additional base type needs to be specified.

This section shows how to define derived entity (complex) types using EdmLib APIs. We will use and extend the sample from the previous section.

Add derived entity type UrgentOrder

In the SampleModelBuilder.cs file, add the following code into the SampleModelBuilder class:

namespace EdmLibSample
{
    public class SampleModelBuilder
    {
        ...
        private EdmEntityType _urgentOrderType;
        ...
        public SampleModelBuilder BuildUrgentOrderType()
        {
            _urgentOrderType = new EdmEntityType("Sample.NS", "UrgentOrder", _orderType);
            _urgentOrderType.AddStructuralProperty("Deadline", EdmPrimitiveTypeKind.Date);
            _model.AddElement(_urgentOrderType);
            return this;
        }
        ...
    }
}

Then in the Program.cs file, insert the following code into the Main() method:

namespace EdmLibSample
{
    class Program
    {
        public static void Main(string[] args)
        {
            var builder = new SampleModelBuilder();
            var model = builder
                ...
                .BuildOrderType()
#region         !!!INSERT THE CODE BELOW!!!
                .BuildUrgentOrderType()
#endregion
                ...
                .GetModel();
            WriteModelToCsdl(model, "csdl.xml");
        }
    }
}

This code:

• Defines the derived entity type UrgentOrder within the namespace Sample.NS, whose base type is Sample.NS.Order;
• Adds a structural property Deadline of type Edm.Date;
• Adds the derived entity type to the entity data model.

Add derived complex type WorkAddress

In the SampleModelBuilder.cs file, add the following code into the SampleModelBuilder class:

namespace EdmLibSample
{
    public class SampleModelBuilder
    {
        ...
        private EdmComplexType _workAddressType;
        ...
        public SampleModelBuilder BuildWorkAddressType()
        {
            _workAddressType = new EdmComplexType("Sample.NS", "WorkAddress", _addressType);
            _workAddressType.AddStructuralProperty("Company", EdmPrimitiveTypeKind.String);
            _model.AddElement(_workAddressType);
            return this;
        }
        ...
    }
}

Then in the Program.cs file, insert the following code into the Main() method:

namespace EdmLibSample
{
    class Program
    {
        public static void Main(string[] args)
        {
            var builder = new SampleModelBuilder();
            var model = builder
                .BuildAddressType()
#region         !!!INSERT THE CODE BELOW!!!
                .BuildWorkAddressType()
#endregion
                ...
                .GetModel();
            WriteModelToCsdl(model, "csdl.xml");
        }
    }
}

This code:

• Defines the derived complex type WorkAddress within the namespace Sample.NS, whose base type is Sample.NS.Address;
• Adds a structural property Company of type Edm.String;
• Adds the derived complex type to the entity data model.

Run the sample

Build and run the sample. Then open the file csdl.xml under the output directory. The content should look like the following: