ASP.NET Core MVC 中 Program.cs 中的 System.AggregateException

Question

我有一个使用 Entity Framework Core O/RM 的 ASP.NET Core MVC 应用程序。 我正在我的应用程序中实现通用存储库模式。 有两个实体， Employee和Department 。 有一个上下文类EmployeeDepartmentDetails 。有一个接口IGenericRepository由GenericRepository实现。 GenericRepository有一个EmployeeDepartmentDetails的依赖注入。我的控制器EmployeeController有一个IGenericRepository的依赖注入。

IGenericRepository.cs -

public interface IGenericRepository<TEntity> where TEntity : class
{
    //...
}

GenericRepository.cs - 这里EmployeeDepartmentDetails是我的上下文类，它继承了DBContext类 -

public class GenericRepository<TEntity> :IGenericRepository<TEntity> where TEntity : class
{
    DbSet<TEntity> _dbSet;
    // Dependency Injection 
    private readonly EmployeeDepartmentDetail _employeeDepartmentDetail; 
    public GenericRepository(EmployeeDepartmentDetail employeeDepartmentDetail)
    {
        _employeeDepartmentDetail = employeeDepartmentDetail;
        _dbSet = _employeeDepartmentDetail.Set<TEntity>();
    } 

    //... 
}

程序.cs -

public static void Main(string[] args)
{
    CreateHostBuilder(args).Build().Run(); // I am getting those two exceptions here
}

启动.cs -

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllersWithViews();
    services.AddScoped(typeof(IGenericRepository<Type>), typeof(GenericRepository<Type>)); 
}

EmployeeController.cs -

public class EmployeeController : Controller
{
    private readonly IGenericRepository<Employee> _genericRepository;
    public EmployeeController(IGenericRepository<Employee> genericRepository)
    {
        _genericRepository = genericRepository;
    } 

    //... 
}

当我运行我的应用程序时，我遇到了两个异常 -

System.AggregateException HResult=0x80131500 消息=无法构建某些服务（验证服务描述符“ServiceType：InfrastructureLayer.GenericRepository.Interface.IGenericRepository 1[System.Type] Lifetime: Scoped ImplementationType: InfrastructureLayer.GenericRepository.Implementation.GenericRepository出错1[System.Type] Lifetime: Scoped ImplementationType: InfrastructureLayer.GenericRepository.Implementation.GenericRepository 1[System.Type]'： 1[System.Type]' could not be located. Ensure the type is concrete and services are registered for all parameters of a public constructor.) Source=Microsoft.Extensions.DependencyInjection StackTrace:at Microsoft.Extensions.DependencyInjection.ServiceProvider..ctor(IEnumerable适合类型“InfrastructureLayer.GenericRepository.Implementation.GenericRepository 1[System.Type]' could not be located. Ensure the type is concrete and services are registered for all parameters of a public constructor.) Source=Microsoft.Extensions.DependencyInjection StackTrace:at Microsoft.Extensions.DependencyInjection.ServiceProvider..ctor(IEnumerable构造函数1[System.Type]' could not be located. Ensure the type is concrete and services are registered for all parameters of a public constructor.) Source=Microsoft.Extensions.DependencyInjection StackTrace:at Microsoft.Extensions.DependencyInjection.ServiceProvider..ctor(IEnumerable 1 serviceDescriptors, ServiceProviderOptions options) at Microsoft.Extensions.DependencyInjection.ServiceCollectionContainerBuilderExtensions.BuildServiceProvider(IServiceOptions options) at Microsoft.Extensions.DependencyInjection.ServiceProvider..ctor( 1[System.Type]' could not be located. Ensure the type is concrete and services are registered for all parameters of a public constructor.) Source=Microsoft.Extensions.DependencyInjection StackTrace:at Microsoft.Extensions.DependencyInjection.ServiceProvider..ctor(IEnumerable 1 serviceDescriptors, ServiceProviderOptions options)扩展.依赖 encyInjection.DefaultServiceProviderFactory.CreateServiceProvider(IServiceCollection containerBuilder) at Microsoft.Extensions.Hosting.Internal.ServiceFactoryAdapter`1.CreateServiceProvider(Object containerBuilder) at Microsoft.Extensions.Hosting.HostBuilder.CreateServiceProvider() at Microsoft.Extensions.Hosting.HostBuilder.Build( ) 在 C:\\Users\\singh\\Desktop\\MVC\\GenericRepository\\CrudEfCore\\Program.cs:line 16 中的 CrudEfCore.Program.Main(String[] args) 这个异常最初是在这个调用堆栈中抛出的：[外部代码]

内部异常 1：InvalidOperationException：验证服务描述符时出错“ServiceType: InfrastructureLayer.GenericRepository.Interface.IGenericRepository 1[System.Type] Lifetime: Scoped ImplementationType: InfrastructureLayer.GenericRepository.Implementation.GenericRepository 1[System.Type]”：一个合适的无法找到类型“InfrastructureLayer.GenericRepository.Implementation.GenericRepository`1[System.Type]”的构造函数。 确保类型是具体的，并且为公共构造函数的所有参数注册了服务。

内部异常 2：InvalidOperationException：找不到适合类型“InfrastructureLayer.GenericRepository.Implementation.GenericRepository`1[System.Type]”的构造函数。 确保类型是具体的，并且为公共构造函数的所有参数注册了服务。

我无法理解异常，我不知道我在这里做错了什么。 我知道我粘贴了很多代码，但我什至不知道如何解释异常。

Answer 1

这是问题的原因

services.AddScoped(typeof(IGenericRepository<Type>), typeof(GenericRepository<Type>)); 

Type是一个抽象类，如错误消息所述：

确保类型是具体的，并且为公共构造函数的所有参数注册了服务。

注意：强调我的

Next Type不是您在注册通用服务时应该使用的通用参数

在这种情况下，您可以使用（通用）开放类型进行注册，无需注册每个（通用）构造类型：

services.AddScoped(typeof(IGenericRepository<>), typeof(GenericRepository<>)); 

ASP.NET Core 中的引用依赖注入