WCF Service with parameterized constructor

Question

I am using .NET 4.5, C#.NET, WCF Repository Pattern

WCF Service

• Customer.svc: <@ ServiceHost Language="C#" Service="CustomerService" @>
• Order.svc: <@ ServiceHost Language="C#" Service="OrderService" @>
• Sales.svc: <@ ServiceHost Language="C#" Service="SalesService" @>
• Products.svc: <@ ServiceHost Language="C#" Service="ProductsService" @>

Implementing classes

public class CustomerService : Service<Customer>, ICustomerService.cs
{
   private readonly IRepositoryAsync<Customer> _repository;
   public CustomerService(IRepositoryAsync<Customer> repository)
   {
      _repository = repository;
   }
}

public class OrdersService : Service<Orders>, IOrdersService.cs
{
   private readonly IRepositoryAsync<Order> _repository;
   public OrdersService(IRepositoryAsync<Order> repository)
   {
      _repository = repository;
   }
}

public class SalesService : Service<Sales>, ISalesService.cs
{
   private readonly IRepositoryAsync<Sales> _repository;
   public SalesService(IRepositoryAsync<Sales> repository)
   {
      _repository = repository;
   }
}

When I run my WCF service, I get a error like there is no empty constructor. How can I keep these services and implementing classes unchanged and have my WCF service work with those constructors.

Answer 1

WCF itself requires the Service Host to have a default/no-argument constructor; the standard WCF service creation implementation does no fancy activation - and it most certainly does not handle Dependency Injection! - when creating the Service Host object.

To bypass this default requirement, use a WCF Service Host Factory (such as one provided with Castle Windsor WCF Integration ) to create the service and inject dependencies using the appropriate constructor. Other IoCs provided their own integration factories. In this case the IoC-aware service factory creates the service and wires up the dependencies.

To use DI without an IoC (or otherwise dealing with a Service Factory), create a no-argument constructor that invokes the constructor with the required dependencies, eg

public class SalesService : Service<Sales>, ISalesService
{
   private readonly IRepositoryAsync<Sales> _repository;

   // This is the constructor WCF's default factory calls
   public SalesService() : this(new ..)
   {
   }

   protected SalesService(IRepositoryAsync<Sales> repository)
   {
      _repository = repository;
   }
}