如何为自托管的 MVC 4 API 控制器配置依赖注入答案

【问题标题】：How to configure dependency injection for self hosted MVC 4 API controllers如何为自托管的 MVC 4 API 控制器配置依赖注入
【发布时间】：2021-10-31 15:22:39
【问题描述】：

在检查了关于 SO 的所有类似问题后，我的问题仍然存在，所以我要为它打开一个新问题。

我有一个引用另一个项目的单元测试，该项目包含一个 MVC 4 ApiController，它有一个用于依赖注入的构造函数。

public class DataController : ApiController
{
    public DataController(IRepository repository){}    
}

在我的测试中，我使用的是Microsoft.Extensions.DependencyInjection 并具有以下设置：

// Note: this redundant type access is necessary to load controllers from a different assembly,
// see https://stackoverflow.com/a/11758025/1468097
var type = typeof(DataController);

var services = new ServiceCollection().AddSingleton<IRepository>(new ImMemoryRepository());
var httpConfiguration = new HttpConfiguration
{ 
    DependencyResolver = new DependencyResolver(services.BuildServiceProvider()),
    IncludeErrorDetailPolicy = IncludeErrorDetailPolicy.Always
};
httpConfiguration.Routes.MapHttpRoute("Default", "{controller}/{action}");
httpConfiguration.DependencyResolver = new DependencyResolver(services.BuildServiceProvider());
var httpServer = new HttpServer(httpConfiguration);
var client = new HttpClient(httpServer);
var response = await client.GetAsync("http://whatever/data/getdata?id=000");

我有一个相当简单的依赖解析器实现，作为测试类中的嵌套私有类：

private class DependencyResolver : IDependencyResolver
{
    private readonly ServiceProvider _serviceProvider;

    public DependencyResolver(ServiceProvider serviceProvider) => _serviceProvider = serviceProvider;

    public void Dispose() => _serviceProvider.Dispose();

    public object GetService(Type serviceType) => _serviceProvider.GetService(serviceType);

    public IEnumerable<object> GetServices(Type serviceType) => _serviceProvider.GetServices(serviceType);

    public IDependencyScope BeginScope() => new Scope(_serviceProvider.CreateScope());

    private class Scope : IDependencyScope
    {
        private readonly IServiceScope _scope;

        public Scope(IServiceScope scope) => _scope = scope;

        public void Dispose() => _scope.Dispose();

        public object GetService(Type serviceType) => _scope.ServiceProvider.GetService(serviceType);

        public IEnumerable<object> GetServices(Type serviceType) => _scope.ServiceProvider.GetServices(serviceType);
    }
}

我从测试中得到的响应是 500 服务器错误提示

Type 'Mvc.DataController' does not have a default constructor

似乎我正在做所有其他人在 MVC 4 中为依赖注入所做的事情，即使是 this question that has a very similar symptom。

我在这里遗漏了什么明显的东西吗？

更新

我试过NinjectResolver 归结为同样的问题：

var kernel = new StandardKernel();
kernel.Bind<IRepository>().ToConstant(new InMemoryRepository());
var httpConfiguration = new HttpConfiguration
{
    DependencyResolver = new NinjectResolver(kernel)
};

【问题讨论】：

标签： asp.net asp.net-mvc asp.net-mvc-4 asp.net-web-api

【解决方案1】：

我想通了。

关键是你还需要在依赖配置中添加你要点击的控制器。

就我而言，我只需要添加：

var services = new ServiceCollection();

// This is what was missing.
services.AddTransient<DataController>();

取自这里（虽然我根本没有使用 OWIN）：How to add Microsoft.Extensions.DependencyInjection to OWIN Self-Hosted WebApi

另一个使用 Autofac 的例子：

var builder = new ContainerBuilder();

// You need to register the assembly that contains your controller.
builder.RegisterApiControllers(typeof(DataController).Assembly);

取自这里：Dependency injection not working with Owin self-hosted Web Api 2 and Autofac

【讨论】：