Question

我试图使用DBContextScopeFactory并遇到问题。

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;
    }

}

单元测试工作得很好，因为它与演示应用程序项目类似。（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());

但是我收到了一个服务器错误：“类型IDbContextFactory没有可访问的构造函数。”

我也尝试过：

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

并且还收到了错误。我很确定这是我注册这个新实现的方式。提前感谢您的帮助。

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'Unity.AspNet.WebApi 3.5.1404.0'＆amp;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移至UnityConfig.cs文件。最后，我从

修改了Global.asax.cs

 UnityConfig.RegisterComponents();

到

 UnityWebApiActivator.Start();

最后我的webAPI正在运行。然而，我仍然在MVC方面得到同样的例外。

[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＆amp; canBeCached，RuntimeMethodHandleInternal＆amp; ctor，Boolean＆amp; bNeedSecurityCheck）+0 System.RuntimeType.CreateInstanceSlow（Boolean publicOnly，Boolean skipCheckThis，Boolean fillCache，StackCrawlMark＆amp; stackMark）+119 System.RuntimeType.CreateInstanceDefaultCtor（Boolean publicOnly，Boolean skipCheckThis，Boolean fillCache，StackCrawlMark＆amp; stackMark）+232 System.Activator.CreateInstance（Type type，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”类型的控制器时发生错误。确保控制器具有无参数的公共构造函数。] 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＆amp; controller，IControllerFactory＆amp; 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 context，AsyncCallback cb，Object extraData）+50 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute（）+103 System.Web.HttpApplication.ExecuteStep（IExecutionStep step，Boolean＆amp; completedSynchronously）+155

我有一个构造函数

public class VendorController : Controller
{
    IVendorService _VendorService;

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

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

Answer 1

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（因为问题的标记意味着）。此外，在注册期间但在实例化控制器期间未发生错误。

Web API尝试使用您没有的默认构造函数来实例化控制器（因为您预计会将依赖项注入构造函数中）。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。

我发现您正在使用PerResolveLifetimeManager - 您可能需要考虑更改为使用随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。

Answer 2

错误消息清楚地说明了问题所在。您尚未正确设置IControllerFactory或IDependencyResolver以解析Unity的实例。这与您的注册无关。

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

OR

DependencyResolver.SetResolver(new UnityDependencyResolver(container));

请注意，您可以自己构建其中一个，也可以从某个地方使用库存实现。但请注意using IControllerFactory is considered the "correct" approach to DI。

将DbContextScopeFactory与Unity

2 个答案: