在 Unity 中使用 DbContextScopeFactory

Question

我正在尝试使用 DBContextScopeFactory 和运行成一个问题。

public class VendorRepository : IVendorRepository
{
    private readonly IDbContextScopeFactory _dbContextScopeFactory;

    public VendorRepository(IDbContextScopeFactory dbContextScopeFactory)
    {
        if (dbContextScopeFactory == null)
        {
            throw new ArgumentNullException("dbContextScopeFactory");
        }
        _dbContextScopeFactory = dbContextScopeFactory;
    }
    public IList<MyVendor> GetMyVendors(int requestorId)
    {
        IList<MyVendor> vndrsList = null;
        using (var dbContextScope = _dbContextScopeFactory.CreateReadOnly())
    {
            var dbContext = dbContextScope.DbContexts.Get<VendorMgmtContext>();
            var vndrs = (from a in dbContext.sp_GetVendorByRequestor(requestorId)
                     select new MyVendor
                     {
                         VendorId = a.VendorId,
                         VendorName = a.VendorName,
                         CreatedByUserId = a.CreatedByUserId,
                         CreatedDate = a.CreatedDate
                         });
            vndrsList = vndrs.ToList();
        }
        return vndrsList;
    }

}

单元测试效果很好，因为它类似于演示应用程序项目。（换句话说，我没有在 UnityConfig.cs 文件中注册它。

[TestMethod]
public void GetMyVendors()
{
    // Arrange
    var dbContextScope = new DbContextScopeFactory();
    var db = new VendorMgmtContext();
    VendorRepository repository = new VendorRepository(dbContextScope);
    IEnumerable<MyVendor> myVendor = null;

    // Act
    myVendor = repository.GetMyVendors(3);

    // Assert
    Assert.IsNotNull(myVendor);
}

所以现在我不太确定如何在 UnityConfig.cs 文件中注册它我试过了：

container.RegisterType<IAmbientDbContextLocator, AmbientDbContextLocator>();
container.RegisterType<IDbContextScopeFactory, DbContextScopeFactory>();
container.RegisterType<VendorMgmtContext, VendorMgmtContext>(new PerResolveLifetimeManager(), new InjectionConstructor());
container.RegisterType<IVendorRepository, VendorRepository>(new PerResolveLifetimeManager());
container.RegisterType<IVendorService, VendorService>(new PerResolveLifetimeManager());

但是我收到一个服务器错误："The type IDbContextFactory does not have an accessible constructor. "

我也试过：

container.RegisterType<IAmbientDbContextLocator, AmbientDbContextLocator>();
container.RegisterType<IDbContextScopeFactory, DbContextScopeFactory>(new InjectionFactory((a) => new DbContextScopeFactory()));

并且还收到错误。我很确定这是我注册这个新实现的方式。预先感谢您的帮助。

更新：注册错误：

container.RegisterType<IDbContextScopeFactory, DbContextScopeFactory>(new InjectionFactory((a) => new DbContextScopeFactory()));

Message: "An error occurred when trying to create a controller of type 'VendorController'. 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)
at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request)
at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsyncCore(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__0.MoveNext()
InnerException:
Message: "Type 'Portal.Controllers.Api.VendorController' does not have a default constructor"
ExceptionType: System.ArgumentException
StackTrace:
at System.Linq.Expressions.Expression.New(Type type)
at System.Web.Http.Internal.TypeActivator.Create[TBase](Type instanceType)
at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator)
at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)

更新 #2 - 更新了 'Unity.AspNet.WebApi 3.5.1404.0' 并将 Unity 从 'Unity 3.0.1304.1' 更新为 'Unity 3.5.1404.0' 我还将所有注册从 WebApiConfig.cs 移到了 UnityConfig.cs文件。最后，我从

修改了 Global.asax.cs

 UnityConfig.RegisterComponents();

到

 UnityWebApiActivator.Start();

我的 webAPI 终于可以运行了。然而，我仍然在 MVC 端遇到相同的异常。

[MissingMethodException: 没有为此对象定义无参数构造函数。] System.RuntimeTypeHandle.CreateInstance(RuntimeType 类型, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +119 System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +232 System.Activator.CreateInstance(Type类型，Boolean nonPublic) +83 System.Activator.CreateInstance(类型类型)+11 System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +110

[InvalidOperationException：尝试创建 'Portal.Controllers.VendorController' 类型的控制器时出错。确保控制器具有无参数 public 构造函数。] System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +247 System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +437 System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +257 System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +326 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback 回调, 对象状态) +157 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback 回调, 对象状态) +88 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest（HttpContext 上下文，AsyncCallback cb，对象 extraData）+50 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +103 System.Web.HttpApplication.ExecuteStep（IExecutionStep 步骤，布尔型& completedSynchronously）+155

我有构造函数

public class VendorController : Controller
{
    IVendorService _VendorService;

    public VendorController(IVendorService VendorSvc)
    {
        _VendorService = VendorSvc;
    }

    // GET: Vendor
    public ActionResult Index()
    {
        return View();
    }
}

Answer 1

错误消息清楚地说明了问题所在。您没有正确设置 IControllerFactory 或 IDependencyResolver 以使用 Unity 解析实例。与您的注册无关。

ControllerBuilder.Current.SetControllerFactory(new UnityControllerFactory(container));

或

DependencyResolver.SetResolver(new UnityDependencyResolver(container));

请注意，您可以自己构建其中一个，也可以使用来自某处的现有实现。但还要注意 using IControllerFactory is considered the "correct" approach to DI.

Answer 2

根据您发布的堆栈跟踪，您似乎正在尝试调用 Web API 控制器而不是 ASP.NET Mvc 控制器（正如问题的标签所暗示的那样）。此外，错误不是在注册期间发生，而是在控制器实例化期间发生。

Web API 尝试使用您没有的默认构造函数来实例化控制器（因为您期望将依赖项注入构造函数）。您需要将 Unity 设置为依赖项解析器以连接控制器依赖项。您可以从 NuGet 添加 Unity bootstrapper for ASP.NET Web API。这将为您注册一个 UnityDependencyResolver（在 UnityWebApiActivator.cs 中）：

var resolver = new Microsoft.Practices.Unity.WebApi.UnityDependencyResolver(UnityConfig.GetConfiguredContainer());

GlobalConfiguration.Configuration.DependencyResolver = resolver;

您还可以将所有注册码移至 UnityConfig.cs。

我看到您正在使用 PerResolveLifetimeManager -- 您可能需要考虑更改为使用与 Unity bootstrapper for ASP.NET MVC 一起安装的 PerRequestLifetimeManager。 PerRequestLifetimeManager 将在 Web 请求结束时自动处理 IDisposable 对象。

在 Unity 中使用 DbContextScopeFactory

Using DbContextScopeFactory with Unity

c#

asp.net-mvc

entity-framework

unity-container