I have service which implements multiple Interfaces; for example
ServiceClass : IService1, IService2
{
// implementation
}
Now I need to register this service in ConfigureServices() in such a way that I have a single instance of SerivceClass and this instance can be used even if the IService1 or IService2 is injected via constructor. For ex,
public class SomeClass1: ISomeClass1
{
SomeClass1(IService1 service)
{
...
}
}
public class SomeClass2 : SomeClass2
{
SomeClass2(IService2 service)
{
...
}
}
I have tried registering the ServiceClass using its both Interfaces in ConfigureServices() but it would create multiple instances.
ConfigureServices(){
...
services.AddSingleton<IService1, ServiceClass>();
services.AddSingleton<IService2, ServiceClass>();
services.AddSingleton<ISomeClass1>(
x => new SomeClass1(
x.GetRequiredService<IService1>(),
));
services.AddSingleton<ISomeClass2>(
x => new SomeClass2(
x.GetRequiredService<IService2>(),
));
....
}
I need to find a solution where I can inject the same instance to SomeClass1 and SomeClass2 eventhough the injected interfaces are different.
One way to solve this is to register the implementing class, and then explicitly resolve the multiple interfaces from that:
services.AddSingleton<ServiceClass>();
services.AddSingleton<IService1, ServiceClass>(x => x.GetRequiredService<ServiceClass>());
services.AddSingleton<IService2, ServiceClass>(x => x.GetRequiredService<ServiceClass>());
There's an example of this approach used here for HttpClientFactory for example.
I'm writing a BUnit test for a Razor component that has injected dependencies like this:
#inject IMyFirstService FirstService
#inject IMySecondService SecondService
#code {
// do stuff
}
For my test, I created a fallback service provider MoqServiceProvider that I'm using to register my mocked dependencies. But I also want the fallback service provider to provide a Moq<MyType> instance by default for any types which I haven't explicitly mocked.
The fallback service provider looks like this
public class MockServiceProvider : IServiceProvider
{
private readonly Dictionary<Type, object> services = new();
public void RegisterServices(params object[] serviceInstances)
{
this.services.Clear();
foreach (object serviceInstance in serviceInstances)
{
if (serviceInstance is Mock)
{
this.services.Add(serviceInstance.GetType().GetGenericArguments().First(), (serviceInstance as Mock).Object);
}
else
{
this.services.Add(serviceInstance.GetType(), serviceInstance);
}
}
}
public object GetService(Type serviceType)
{
if (this.services.TryGetValue(serviceType, out object service))
{
return service;
}
else
{
// I want to return a Mock of serviceType here
// something like return new Mock<serviceType>(), but I don't know how to do that
}
}
}
I'm using it like this in a test (I'm using AutoFixture to provide the test parameters):
#inherits TestContext
#code{
[Theory, AutoDomainData]
public void TestSomething(
Mock<IMyFirstService> myFirstService,
MockServiceProvider serviceProvider)
{
serviceProvider.RegisterServices(myFirstService);
Services.AddFallbackServiceProvider(serviceProvider);
var component = Render(#<MyComponent />);
// do stuff to test
}
}
If I run this, I'll get an error Cannot provide a value for property 'SecondService' on type 'MyComponent' since I haven't registered an instance of a Mock<IMySecondService> with MockServiceProvider.
How do I have MockServiceProvider return a mock of every type which I haven't registered explicity (something like return Mock<serviceType)? Some of my Razor components have a lot of dependencies and I don't want to have to inject the ones that don't matter for each test.
A fallback service provider added to bUnit's root service provider is invoked if the root service provider cannot resolve a GetService request. With that info in mind, we can use Moq (or another mocking framework) and a little Reflection trickery to create a fallback service provider, which is really just something that implements the IServiceProvider interface, that will use Moq to create a mocked version of a requested service, when its GetService method is called.
AutoMockingServiceProvider
This service provider will use Mock to create a mock of a requested service type once, and any subsequent requests will get the same type returned (they are saved in the mockedTypes dictionary).
The reason for this is that you can retrieve the same mocked instance of a type in both your test and in the component under test, which allows you to configure the mock in your test.
The GetMockedService extension method below makes it easy to pull out a Mock<T> from the service provider.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using Microsoft.Extensions.DependencyInjection;
using Moq;
public class AutoMockingServiceProvider : IServiceProvider
{
private static readonly MethodInfo GenericMockFactory = typeof(Mock).GetMethods().First(x => x.Name == "Of");
private readonly Dictionary<Type, object> mockedTypes = new();
public object? GetService(Type serviceType) => GetMockedService(serviceType);
public object GetMockedService<T>() => GetMockedService(typeof(T));
public object GetMockedService(Type serviceType)
{
if (!mockedTypes.TryGetValue(serviceType, out var service))
{
var mockFactory = GenericMockFactory.MakeGenericMethod(serviceType);
service = mockFactory.Invoke(null, Array.Empty<object>())!;
mockedTypes.Add(serviceType, service);
}
return service;
}
}
internal static class ServiceProviderExtensions
{
public static Mock<T> GetMockedService<T>(this IServiceProvider services)
where T : class => Mock.Get<T>(services.GetService<T>()!);
}
NOTE: This code doesn't deal with any edge cases, so it might not work in all cases, but should serve as a good starting point.
Example usage
Suppose we have the following component:
#inject IPerson Person
#Person.Name
That depends on this interface:
public interface IPerson
{
public string Name { get; }
}
Then it can be tested like this:
[Fact]
public void Test1()
{
using var ctx = new TestContext();
// Add the AutoMockingServiceProvider as the fallback service provider
ctx.Services.AddFallbackServiceProvider(new AutoMockingServiceProvider());
// Retrieves the mocked person from the service collection and configures it.
var mockedPerson = ctx.Services.GetMockedService<IPerson>();
mockedPerson.SetupGet(x => x.Name).Returns("Foo Bar");
// Render component
var cut = ctx.RenderComponent<MyComp>();
// Verify content
cut.MarkupMatches("Foo Bar");
}
This was tested with .NET 6 rc.1, Moq 4.16.1, and bunit 1.2.49.
I have three types of users in my application, let's say Type1, Type2 and Type3.
Then i want to create one service implementation for each type, let's say i have a service to get photos, i would have three services : Type1PhotosService, Type2PhotosService and Type3PhotosService, each of them implementing IPhotosService.
In the web api, i would inject IPhotosService :
IPhotosService _service;
public PhotosController(IPhotosService service){
_service = service;
}
The web api uses token authentication with claims. So what i want to achieve, is for each user, depending on the claim he has : type1 or type2 or type3, the correct implementation of the service will be automatically injected rather than injecting a single service in the startup file.
What i want to avoid, is having one service, with a bunch of switch and if statements to return the correct data depending on user type and the roles he has.
EDIT:
some comments were wondering what's the point of three implementations, so here are more details to give it a little more sense.
The service is a job finder service, and the application has three different profiles : candidate, employer and administration. Each of these profiles need a proper implementation. So rather than having three methods GetCandidateJobs, GetEmployerJobs and GetAdministrationJobs inside the same service and switch on the user type, i preferred to have one implementation per profile type, then depending on the profile type, use the correct implementation.
Without Using a Separate IoC Container
Here's an approach that's way easier than configuring your app to use another IoC container and then configuring that container. After working through this with Windsor this solution seems a whole lot easier.
This approach is simplest if you can use a singleton instance of each service implementation.
We'll start with an interface, some implementations, and the factory we can inject which will return an implementation selected at runtime based on some input.
public interface ICustomService { }
public class CustomServiceOne : ICustomService { }
public class CustomServiceTwo : ICustomService { }
public class CustomServiceThree : ICustomService { }
public interface ICustomServiceFactory
{
ICustomService Create(string input);
}
Here's a really crude implementation of the factory. (Didn't use string constants, or polish it at all.)
public class CustomServiceFactory : ICustomServiceFactory
{
private readonly Dictionary<string, ICustomService> _services
= new Dictionary<string, ICustomService>(StringComparer.OrdinalIgnoreCase);
public CustomServiceFactory(IServiceProvider serviceProvider)
{
_services.Add("TypeOne", serviceProvider.GetService<CustomServiceOne>());
_services.Add("TypeTwo", serviceProvider.GetService<CustomServiceTwo>());
_services.Add("TypeThree", serviceProvider.GetService<CustomServiceThree>());
}
public ICustomService Create(string input)
{
return _services.ContainsKey(input) ? _services[input] : _services["TypeOne"];
}
}
This assumes that you've already registered CustomServiceOne, CustomServiceTwo, etc. with the IServiceCollection. They would not be registered as interface implementations, since that's not how we're resolving them. This class will simply resolve each one and put them in a dictionary so that you can retrieve them by name.
In this case the factory method takes a string, but you could inspect any type or multiple arguments to determine which implementation to return. Even the use of a string as the dictionary key is arbitrary. And, just as an example, I provided fallback behavior to return some default implementation. It might make more sense to throw an exception instead if you can't determine the right implementation to return.
Another alternative, depending on your needs, would be to resolve the implementation within the factory when it's requested. To the extent possible I try to keep most classes stateless so that I can resolve and reuse a single instance.
To register the factory with the IServiceCollection at startup we would do this:
services.AddSingleton<ICustomServiceFactory>(provider =>
new CustomServiceFactory(provider));
The IServiceProvider will be injected into the factory when the factory is resolved, and then the factory will use it to resolve the service.
Here's the corresponding unit tests. The test method is the identical to the one used in the Windsor answer, which "proves" that we can transparently replace one factory implementation with another and change other stuff in the composition root without breaking stuff.
public class Tests
{
private IServiceProvider _serviceProvider;
[SetUp]
public void Setup()
{
var services = new ServiceCollection();
services.AddSingleton<CustomServiceOne>();
services.AddSingleton<CustomServiceTwo>();
services.AddSingleton<CustomServiceThree>();
services.AddSingleton<ICustomServiceFactory>(provider =>
new CustomServiceFactory(provider));
_serviceProvider = services.BuildServiceProvider();
}
[TestCase("TypeOne", typeof(CustomServiceOne))]
[TestCase("TypeTwo", typeof(CustomServiceTwo))]
[TestCase("TYPEThree", typeof(CustomServiceThree))]
[TestCase("unknown", typeof(CustomServiceOne))]
public void FactoryReturnsExpectedService(string input, Type expectedType)
{
var factory = _serviceProvider.GetService<ICustomServiceFactory>();
var service = factory.Create(input);
Assert.IsInstanceOf(expectedType, service);
}
}
As in the Windsor example, this is written to avoid any reference to the container outside of the composition root. If a class depends on ICustomServiceFactory and ICustomService you could switch between this implementation, the Windsor implementation, or any other implementation of the factory.
Using Windsor
I'm going to sidestep the questions about whether or not this makes sense in this case and just attempt to answer the question as asked:
.NET Core's IoC container isn't built particularly well for this sort of scenario. (They acknowledge this in their documentation.) You can work around it by adding another IoC container like Windsor.
The implementation ended up looking way more complicated than I would have liked, but once you get past the setup it's not bad and you get access to Windsor's features. I'm going to provide another answer that doesn't include Windsor. I had to do all of this work to see that I probably like the other approach better.
In your project, add the Castle.Windsor.MsDependencyInjection NuGet package.
Interfaces and Implementations for Testing
For testing, I added some interfaces and implementations:
public interface ICustomService { }
public interface IRegisteredWithServiceCollection { }
public class CustomServiceOne : ICustomService { }
public class CustomServiceTwo : ICustomService { }
public class CustomServiceThree : ICustomService { }
public class RegisteredWithServiceCollection : IRegisteredWithServiceCollection { }
The intent is to create a factory that will select and return an implementation of ICustomService using some runtime input.
Here's an interface which will serve as a factory. This is what we can inject into a class and call at runtime to get an implementation of ICustomService:
public interface ICustomServiceFactory
{
ICustomService Create(string input);
}
Configure the Windsor Container
Next is a class which will configure an IWindsorContainer to resolve dependencies:
public class WindsorConfiguration : IWindsorInstaller
{
public void Install(IWindsorContainer container, IConfigurationStore store)
{
container.AddFacility<TypedFactoryFacility>();
container.Register(
Component.For<ICustomService, CustomServiceOne>().Named("TypeOne"),
Component.For<ICustomService, CustomServiceTwo>().Named("TypeTwo"),
Component.For<ICustomService, CustomServiceThree>().Named("TypeThree"),
Component.For<ICustomService, CustomServiceOne>().IsDefault(),
Component.For<ICustomServiceFactory>().AsFactory(new CustomServiceSelector())
);
}
}
public class CustomServiceSelector : DefaultTypedFactoryComponentSelector
{
public CustomServiceSelector()
: base(fallbackToResolveByTypeIfNameNotFound: true) { }
protected override string GetComponentName(MethodInfo method, object[] arguments)
{
return (string) arguments[0];
}
}
Here's what's going on in here:
The TypedFactoryFacility will enable us to use Windsor's typed factories. It will create an implementation of our factory interface for us.
We're registering three implementations of ICustomService. Because we're registering more than one implementation, each must have a name. When we resolve ICustomService we can specify a name, and it will resolve the type according to that string.
For illustration I registered another implementation of ICustomService without a name. That will enable us to resolve a default implementation if we try to resolve using an unrecognized name. (Some alternatives are just throwing an exception, or returning a "null" instance of ICustomService or creating a class like UnknownCustomService that throws an exception.)
Component.For<ICustomServiceFactory>().AsFactory(new CustomServiceSelector()) tells the container to create a proxy class to implement ICustomServiceFactory. (More on that in their documentation.)
CustomServiceSelector is what takes the argument passed to the factory's Create method and returns the component name (TypeOne, TypeTwo, etc.) that will be used to select a component. In this case we're expecting that the argument passed to the factory will be the same as the registration name we've used. But we could replace this with other logic. Our factory could even take arguments of other types which we could inspect and determine which string to return.
Configure Your App To Use the Windsor Container
Now, in StartUp, modify ConfigureServices to return IServiceProvider instead of void and create an IServiceProvider that combines services registered directly with the IServiceCollection with those registered with the Windsor container:
public IServiceProvider ConfigureServices(IServiceCollection services)
{
services.AddMvc();
var container = new WindsorContainer();
container.Install(new WindsorConfiguration());
return WindsorRegistrationHelper.CreateServiceProvider(container, services);
}
container.Install(new WindsorConfiguration()) allows WindsorConfiguration to configure our container. We could just configure the container right in this method, but this is a nice way to keep our container configurations organized. We can create numerous IWindsorInstaller implementations or our own custom classes to configure the Windsor container.
WindsorRegistrationHelper.CreateServiceProvider(container, services) creates the IServiceProvider that uses container and services.
Does It Work?
I wouldn't post all this without finding out first. Here's some NUnit tests. (I usually write some basic tests for DI configuration.)
The setup creates an IServiceProvider similar to what would happen in the application startup. It creates a container and applies the WindsorConfiguration. I'm also registering a service directly with the ServiceCollection to make sure that the two play well together. Then I'm combining the two into an IServiceProvider.
Then I'm resolving an ICustomerServiceFactory from the IServiceProvider and verifying that it returns the correct implementation of ICustomService for each input string, including the fallback when the string isn't a recognized dependency name.
I'm also verifying that the service registered directly with ServiceCollection is resolved.
public class Tests
{
private IServiceProvider _serviceProvider;
[SetUp]
public void Setup()
{
var services = new ServiceCollection();
services.AddSingleton<IRegisteredWithServiceCollection, RegisteredWithServiceCollection>();
var container = new WindsorContainer();
container.Install(new WindsorConfiguration());
_serviceProvider = WindsorRegistrationHelper.CreateServiceProvider(container, services);
}
[TestCase("TypeOne", typeof(CustomServiceOne))]
[TestCase("TypeTwo", typeof(CustomServiceTwo))]
[TestCase("TYPEThree", typeof(CustomServiceThree))]
[TestCase("unknown", typeof(CustomServiceOne))]
public void FactoryReturnsExpectedService(string input, Type expectedType)
{
var factory = _serviceProvider.GetService<ICustomServiceFactory>();
var service = factory.Create(input);
Assert.IsInstanceOf(expectedType, service);
}
[Test]
public void ServiceProviderReturnsServiceRegisteredWithServiceCollection()
{
var service = _serviceProvider.GetService<IRegisteredWithServiceCollection>();
Assert.IsInstanceOf<RegisteredWithServiceCollection>(service);
}
}
Is All of This Worth It?
Now that I've figured it out, I'd probably use it if I really needed this sort of functionality. It looks worse if you're trying to assimilate both using Windsor with .NET Core and seeing it's abstract factory implementation for the first time. Here's another article with some more information on Windsor's abstract factory without all the noise about .NET Core.
I am going to go out on a limb here and say that the attempt to utilize dependency injection for this purpose is sub-optimal. Normally this would be handled by a Factory pattern that produces service implementations using the dreaded if and switch statements. A simple example is:
public interface IPhotoService {
Photo CreatePhoto(params);
}
public class PhotoServiceFactory {
private readonly IPhotoService _type1;
private readonly IPhotoService _type2;
private readonly IPhotoService _type3;
public PhotoServiceFactory(IDependency1 d1, IDependency2 d2, ...etc) {
_type1 = new ConcreteServiceA(d1);
_type2 = new ConcreteServiceB(d2);
_type3 = new ConcreteServiceC(etc);
}
public IPhotoService Create(User user) {
switch(user.Claim) {
case ClaimEnum.Type1:
return _type1;
case ClaimEnum.Type2:
return _type2;
case ClaimEnum.Type3:
return _type3;
default:
throw new NotImplementedException
}
}
}
Then in your controller:
public class PhotosController {
IPhotoServiceFactory _factory;
public PhotosController(IPhotoServiceFactory factory){
_factory = factory;
}
public IHttpActionResult GetPhoto() {
var photoServiceToUse = _factory.Create(User);
var photo = photoServiceToUse.CreatePhoto(params);
return Ok(photo);
}
}
Alternately just use the concrete classes as arguments in the constructor and follow a similar logic as to the above.
Here is one solution, i have created inside asp.net core console application.
using System;
using System.Collections.Generic;
using Microsoft.Extensions.DependencyInjection;
namespace CreationalPattern
{
class Program
{
static void Main(string[] args)
{
// Add dependency into service collection
var services = new ServiceCollection()
.AddTransient<FordFigoFactory>()
.AddTransient<AudiQ7Factory>();
/* Create CarServiceFactory as singleton because it can be used across the application more frequently*/
services.AddSingleton<ICarServiceFactory>(provider => new CarServiceFactory(provider));
// create a service provider from the service collection
var serviceProvider = services.BuildServiceProvider();
/* instantiate car*/
var factory = serviceProvider.GetService<ICarServiceFactory>();
var audiCar = factory.Create("audi").CreateACar("Blue");
Console.Read();
}
}
public interface ICarServiceFactory
{
ICreateCars Create(string input);
}
public class CarServiceFactory : ICarServiceFactory
{
private readonly Dictionary<string, ICreateCars> _services
= new Dictionary<string, ICreateCars>(StringComparer.OrdinalIgnoreCase);
public CarServiceFactory(IServiceProvider serviceProvider)
{
_services.Add("ford", serviceProvider.GetService<FordFigoFactory>());
_services.Add("audi", serviceProvider.GetService<AudiQ7Factory>());
}
public ICreateCars Create(string input)
{
Console.WriteLine(input + " car is created.");
return _services.ContainsKey(input) ? _services[input] : _services["ford"];
}
}
public interface ICreateCars
{
Car CreateACar(string color);
}
public class FordFigoFactory : ICreateCars
{
public Car CreateACar(string color)
{
Console.WriteLine("FordFigo car is created with color:" + color);
return new Fordigo { Color = color};
}
}
public class AudiQ7Factory : ICreateCars
{
public Car CreateACar(string color)
{
Console.WriteLine("AudiQ7 car is created with color:" + color);
return new AudiQ7 { Color = color };
}
}
public abstract class Car
{
public string Model { get; set; }
public string Color { get; set; }
public string Company { get; set; }
}
public class Fordigo : Car
{
public Fordigo()
{
Model = "Figo";
Company = "Ford";
}
}
public class AudiQ7 : Car
{
public AudiQ7()
{
Model = "Audi";
Company = "Q7";
}
}
}
Explanation:
To understand better try to read the program from bottom to top. We have 3 sections:
Car (Car, Fordigo, AudiQ7)
CarFactory (ICreateCars, FordFigoFactory, AudiQ7Factory)
CarService (ICarServiceFactory, CarServiceFactory)
In this Dependency injection is registered as transient for Factory classes FordFigoFactory and AudiQ7Factory. And Singleton for CarServiceFactory.
I’m using Service Stack, and I can´t (or I don´t know how make a Service class with constructor).
Here is what I did:
public class AppHost : AppSelfHostBase
{
public AppHost()
: base("ClientService", typeof(ClientService).Assembly)
{
}
public override void Configure(Container container)
{
}
}
public class Context : ApplicationContext
{
//This class is invoked from program.cs (winform application)
//Here i have the logic of what form should i start.
var listeningOn = string.Format("http://*:{0}/", port);
var appHost = new AppHost();
appHost.Init();
appHost.Start(listeningOn);
ClientService cl = new ClientService((ILayout)f, i);
}
public class ClientService : Service
{
private readonly ILayout _activeForm;
private static Init _initConf;
public ClientService(ILayout f, Init i)
{
_activeForm = f;
_activeForm.GetClientData(i);
_initConf = i;
}
public HttpResult Post(Person request)
{
//Here i use _activeForm and _initConf
}
}
So, as I said, in the class ClientService, I wanna make a constructor, but when I make a request to the post message, it shows me the following error:
Error trying to resolve Service
'DexBrokerClient.Services.ClientService' or one of its auto wired
dependencies
ServiceStack Services are autowired and created using both Constructor and Property Injection. Any Constructor parameters are mandatory and must be registered in ServiceStack's IOC in AppHost.Configure(), e.g:
public override void Configure(Container container)
{
container.Register<ILayout>(c => ...);
container.Register<Init>(c => ...);
}
Whereas any public properties on Services are optional and will be populated from the IOC if they exist or are otherwise null.
Resolving Services
Services should be resolved using base.ResolveService<T> API's when inside Service class or HostContext.ResolveService<T>() singleton outside of Services. This resolves the Service class from ServiceStack's IOC and is populated with the IRequest context (if any).
#Mati, #TheMiddleMan The #mythz's answer expects you to have some general knowledge about dependency injection and containers that is IOC (inversion of control). In your question you ask about constructor injection. ServiceStack's IOC can handle it using auto-wiring if you have pre-configured (registered) the parameter object, for example:
container.Register(c => new Layout());
For more samples see https://docs.servicestack.net/ioc.
More about IOC and DI (dependency injection) can be read from https://dzone.com/articles/ioc-vs-di.
I am experimenting with a throwaway vNext application. What I'm trying to do is create a dummy class called 'DataService' which will return some data, and then create objects which use DI to take an IDataService parameter as the constructor.
So my IDataService/DataService definitions are:
public interface IDataService
{
DateTime Created { get; }
}
public class DataService : IDataService
{
private DateTime created = DateTime.Now;
public DateTime Created
{
get { return created; }
}
}
In my startup class I register this as a singleton:
public void Configure(IApplicationBuilder app)
{
app.UseServices(services =>
{
services.AddSingleton<Data.IDataService, Data.DataService>();
});
And in a class I created, I add the IDataService interface as a constructor dependency:
internal class Constraint : IRouteConstraint
{
private readonly IDataService _dataService;
public Constraint (IDataService dataService)
{
_dataService = dataService;
}
public bool Match(....)
{
//call dataservice for match
}
}
The class here with the constructor dependency is an IRouteConstraint which I'm trying to use to get dynamic routes in MVC - the final part of the startup class code is this:
app.UseMvc(routes => {
routes.MapRoute(name: "TestRoute", template: "{*constraints}", defaults: new { controller = "Test", action = "Index" }, constraints: new { constraint = new Constraint() }); //<--- how to construct using DI?
});
The issue is that the Constraint() class can't be created because it is missing the constructor. All the examples show a Controller using DI and the instantiation of the Controller classes are handled by MVC so that is part of the 'automagic' we don't see at first glance.
So my question is:
How do I instantiate the 'Constraint' object so that DI provides the implementation of the DataService singleton?
Is my issue because I'm trying this in the Configure method in the UseMvc method, or is my problem more fundamental than that?
I figure I'm missing some way of getting DI to act as an object factory to provide my objects instead of trying to declaratively creating them.
If you're wanting to resolve your Constraint through the Dependency Injection, you'll need to register it, first:
services.AddTransient<Constraint>();
Once you have the IApplicationBuilder, you can access the services directly:
app.ApplicationServices.GetRequiredService<Constraint>();
Of course, if you don't want to add your Constraint type to the services list, you can still access the IDataService the same way.
This assumes you have using Microsoft.Framework.DependencyInjection; declared at the top of your Startup; given your other syntax, I believe that you do.