Ninject and Dependency Injection WebApi Attributes

Question

我使用Ninject：

public static class NinjectWebCommon
{
private static readonly Bootstrapper bootstrapper = new Bootstrapper();
/// <summary>
/// Starts the application
/// </summary>
public static void Start()
{
DynamicModuleUtility.RegisterModule(typeof(OnePerRequestHttpModule));
DynamicModuleUtility.RegisterModule(typeof(NinjectHttpModule));
bootstrapper.Initialize(CreateKernel);
}
/// <summary>
/// Stops the application.
/// </summary>
public static void Stop()
{
bootstrapper.ShutDown();
}
/// <summary>
/// Creates the kernel that will manage your application.
/// </summary>
/// <returns>The created kernel.</returns>
private static IKernel CreateKernel()
{
var kernel = new StandardKernel();
var resolver = new NinjectSignalRDependencyResolver(kernel);
try
{
kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();
GlobalHost.DependencyResolver = new NinjectSignalRDependencyResolver(kernel);
RegisterServices(kernel);
GlobalConfiguration.Configuration.DependencyResolver = new NinjectResolver(kernel);
return kernel;
}
catch
{
kernel.Dispose();
throw;
}
}
/// <summary>
/// Load your modules or register your services here!
/// </summary>
/// <param name="kernel">The kernel.</param>
private static void RegisterServices(IKernel kernel)
{
kernel.Bind<TMS.Entities.AssetContext>().ToSelf().InRequestScope();
kernel.Bind<TMS.Data.IDbContext>().To<TMS.Entities.AssetContext>().InRequestScope();
kernel.Bind(typeof(TMS.Data.IRepository<>)).To(typeof(TMS.Data.EfRepository<>));
kernel.Bind<IExportManager>().To<ExportManager>().InRequestScope();
kernel.Bind<IDriverService>().To<Services.Drivers.DriverService>().InRequestScope();
.....
}
}

它适用于 Mvc 和 API 控制器。但是现在我正在编写ActionFilter：

public class AccessLoadApiAttribute : ActionFilterAttribute
{
public AccessLoadApiAttribute()
{
}
private readonly ILoadServiceEntity _loadServiceEntity;
public AccessLoadApiAttribute(ILoadServiceEntity loadServiceEntity)
{
_loadServiceEntity = loadServiceEntity ?? throw new ArgumentNullException(nameof(loadServiceEntity));
}
public override void OnActionExecuting(HttpActionContext actionContext)
{
var loadId = Convert.ToInt32(actionContext.RequestContext.RouteData.Values["Id"]);
_loadServiceEntity.GetLoadById(loadId);
base.OnActionExecuting(actionContext);
}
}

并且_loadServiceEntity为空。配置有什么问题？

Answer 1

在 Web API 2.x Asp.Net 中，如果要在单个操作上使用属性，则不允许通过构造函数注入依赖项。

您必须通过可通过IDependencyResolver使用服务定位器

反模式，该反模式可通过HttpConfiguration

例如

public class AccessLoadApiAttribute : ActionFilterAttribute {
public override void OnActionExecuting(HttpActionContext actionContext) {
//get the resolver via the request context
var resolver = actionContext.RequestContext.Configuration.DependencyResolver;
//use resolver to get dependency
ILoadServiceEntity _loadServiceEntity = (ILoadServiceEntity)resolver.GetService(typeof(ILoadServiceEntity));
var loadId = Convert.ToInt32(actionContext.RequestContext.RouteData.Values["Id"]);
_loadServiceEntity.GetLoadById(loadId);
base.OnActionExecuting(actionContext);
}
}

现在可以根据需要使用该属性

[AccessLoadApi]
[HttpGet]
public IHttpActionResult SomeGetAction() {
return Ok();    
}