When I try to call a controller API endpoint on my application I get this error:
{
"Message": "An error has occurred.",
"ExceptionMessage": "An error occurred when trying to create a controller of type 'ProviderController'. Make sure that the controller has a parameterless public constructor.",
"ExceptionType": "System.InvalidOperationException",
"StackTrace": " at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)\r\n at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request)\r\n at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()",
"InnerException": {
"Message": "An error has occurred.",
"ExceptionMessage": "Type 'mynamespace.api.controllers.ProviderController' does not have a default constructor",
"ExceptionType": "System.ArgumentException",
"StackTrace": " at System.Linq.Expressions.Expression.New(Type type)\r\n at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator)\r\n at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)"
}
}
My configuration is as follows and I am using the Unity.WebAPI library:
Startup.cs
public void Configuration(IAppBuilder app)
{
HttpConfiguration config = GlobalConfiguration.Configuration;
config.DependencyResolver = new UnityDependencyResolver(UnityConfig.GetConfiguredContainer());
app.UseWebApi(WebApiConfig.Register());
app.UseCors(CorsOptions.AllowAll);
config.EnsureInitialized();
}
UnityConfig.cs:
public static class UnityConfig
{
#region Unity Container
/// <summary>
/// Load types in Unity Container
/// </summary>
private static Lazy<IUnityContainer> container = new Lazy<IUnityContainer>(() =>
{
var container = new UnityContainer();
RegisterTypes(container);
return container;
});
/// <summary>
/// Gets the configured Unity container.
/// </summary>
public static IUnityContainer GetConfiguredContainer()
{
return container.Value;
}
#endregion
/// <summary>
/// Register the types into Unity Container.
/// </summary>
/// <param name="container"></param>
public static void RegisterTypes(UnityContainer container)
{
container.RegisterType<IProviderService, ProviderService();
}
}
ProviderController.cs:
public class ProviderController : ApiController
{
private static readonly ILog log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
private readonly IProviderService providerService;
public ProviderController(IProviderService providerService)
{
providerService = providerService;
}
//Controller API Methods
}
ProviderService.cs:
public ProviderService()
{
this.serviceClient = new ServiceClientAdapter();
}
I have spent all morning reading through various threads and am unable to figure out where I am going wrong. If I remove Unity and instantiate a new ProviderService directly in the controller, everything works.
My problem was a small oversight. The call to UseWebApi in Startup.cs was not taking the HttpConfiguration config object as a parameter but was instead declaring it's own. This meant that WebAPI and Unity were configured with different HTTPConfiguration objects and the WebAPI was not aware of Unity as a result.