In my previous post I covered the configuration of the Unity Application Block for Constructor Injection without modifying the class being injected. In this post I will cover Property Injection and how write API and XML configuration.
The following code has a dependency on the ILogger class exposed through a public property in line 10 (Property Injection).
public class MainFormPresenter
{
private readonly IProductRepository _productRepository;
public MainFormPresenter(IProductRepository productRepository)
{
_productRepository = productRepository;
}
public ILogger Logger { protected get; set; }
public IList<Product> GetAllProducts()
{
Logger.Log("Start LINQ Query");
return _productRepository
.Query(p => p.Name.StartsWith("M"))
.OrderBy(p => p.Name)
.ThenByDescending(p => p.ListPrice)
.ToList();
}
}
Without the [Dependency] attribute, Unity has no idea that we need a class created and injected into the Logger Property. Using the container API it’s a trivial matter of informing Unity of our requirements. Lines 9 and 10 in the code below will tell Unity that whenever class MainFormPresenter is created, inject Property “Logger” with a class that matches it’s type. In addition, since the property type is ILogger, Unity needs a mapping to a concrete class or it will throw an exception (line 7).
IUnityContainer unityContainer = new UnityContainer();
//Configure Container
unityContainer
.RegisterType<IProductRepository, ProductRepository>()
.RegisterType<DataContext, AdventureWorksDataContext>()
.RegisterType<ILogger, DebugLogger>();
unityContainer.Configure<InjectedMembers>()
.ConfigureInjectionFor<MainFormPresenter>(new InjectionProperty("Logger"));
The following XML snippet will perform the same configuration
1: <type type="UnityDemo.Views.MainFormPresenter, WindowsFormsApplication3">2: <typeConfig extensionType="Microsoft.Practices.Unity.Configuration.TypeInjectionElement, Microsoft.Practices.Unity.Configuration">3: <property name ="Logger" propertyType="UnityDemo.Logging.ILogger, WindowsFormsApplication3"/>4: </typeConfig>5: </type>
Related Posts:
POCO and Unity Application Block Part I – Constructor Injection
