无法使用 autofac 解决通用存储库的依赖关系答案

【问题标题】：Unable to resolve dependency for generic repository using autofac无法使用 autofac 解决通用存储库的依赖关系
【发布时间】：2019-08-14 04:44:37
【问题描述】：

我正在使用 .net 核心 API 并使用 autofac 解决我的依赖关系。但是不知何故，我无法解决我的通用存储库的依赖关系。

有人可以指导我做错了什么。

startup.cs

var builder = new ContainerBuilder();

builder.RegisterType<UnitOfWork>().As<IUnitOfWork>()
    .InstancePerLifetimeScope();

builder.RegisterType<DatabaseFactory>().As<IDatabaseFactory>()
.InstancePerLifetimeScope();

//This is the place which is not working for me
builder.RegisterGeneric(typeof(Repository<>)).As(typeof(IRepository<>)).InstancePerLifetimeScope();

builder.RegisterAssemblyTypes(typeof(SizeRepository).Assembly)
    .Where(t => t.Name.EndsWith("Repository"))
    .AsImplementedInterfaces()
    .InstancePerLifetimeScope();

builder.RegisterAssemblyTypes(typeof(UserService).Assembly)
    .Where(t => t.Name.EndsWith("Service"))
    .AsImplementedInterfaces()
    .InstancePerLifetimeScope();

builder.Populate(services);
var container = builder.Build();
//Create the IServiceProvider based on the container.
return new AutofacServiceProvider(container);

UnitOfWork.cs

using System.Threading.Tasks;

namespace MakeTalk.Data.Infrastructure
{
public class UnitOfWork : IUnitOfWork
{
    #region Local variable

    private readonly IDatabaseFactory databaseFactory;
    private MakeTalkEntities dataContext;

    #endregion

    #region Constructor
    public UnitOfWork(IDatabaseFactory databaseFactory)
    {
        this.databaseFactory = databaseFactory;
    }
    #endregion

    #region Property
    protected MakeTalkEntities DataContext => dataContext ?? (dataContext = databaseFactory.Get());
    #endregion

    #region Methods
    /// <summary>
    /// Commit changes 
    /// </summary>
    /// <history>Created : 01-04-2018</history>
    public void Commit()
    {
        DataContext.SaveChanges();
    }
    /// <summary>
    /// Commit Async changes
    /// </summary>
    /// <returns></returns>
    /// <history>Created : 01-04-2018</history>
    public async Task<int> CommitAsync()
    {
        return await DataContext.SaveChangesAsync();
    }

    #endregion

}
}

Repository.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;


namespace MakeTalk.Data.Infrastructure
{
    public class Repository<T> : IRepository<T> where T : class
    {
        #region Variable / Properties  
        private MakeTalkEntities dataContext;
        private readonly DbSet<T> dbSet;
        protected MakeTalkEntities DataContext => dataContext ?? (dataContext = DatabaseFactory.Get());
    protected IDatabaseFactory DatabaseFactory
    {
        get;
        private set;
    }
    #endregion

    #region Constructor
    protected Repository(IDatabaseFactory databaseFactory)
    {
        DatabaseFactory = databaseFactory;
        dbSet = DataContext.Set<T>();
    }
    #endregion

    #region Sync Methods

    // all methods ...
    #endregion
}
}

DatabaseFactory.cs

using Microsoft.EntityFrameworkCore;

namespace MakeTalk.Data.Infrastructure
{
    public class DatabaseFactory : Disposable, IDatabaseFactory
    {
        private MakeTalkEntities dataContext;

        public MakeTalkEntities Get()
        {
            return dataContext ?? (dataContext = new MakeTalkEntities(new DbContextOptions<MakeTalkEntities>()));
        }
        protected override void DisposeCore()
        {
            dataContext?.Dispose();
        }
    }
}

MakeTalkEntities.cs

using Microsoft.EntityFrameworkCore;
using MakeTalk.Data.Configuration;
using MakeTalk.Model;

namespace MakeTalk.Data
{
    public class MakeTalkEntities : DbContext
    {
        #region Constructor

        public MakeTalkEntities(DbContextOptions options)
        {

        }

        #endregion

        #region DB Properties 
        // db sets 

        #endregion

        #region Methods

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {


            // ReSharper disable once AssignNullToNotNullAttribute
            optionsBuilder.UseSqlServer("Some-Connection");

            base.OnConfiguring(optionsBuilder);
        }
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {

            // all configutaion 

            base.OnModelCreating(modelBuilder);
        }
        #endregion

    }
}

代码有什么问题吗？我能够解决我的其他存储库和服务，只是面临通用存储库的问题 builder.RegisterGeneric(typeof(Repository)).As(typeof(IRepository)).InstancePerLifetimeScope();

在使用这个通用存储库时，我收到以下错误

Autofac.Core.DependencyResolutionException：在激活特定注册期间发生错误。有关详细信息，请参阅内部异常。注册：Activator = CommonService (ReflectionActivator), Services = [MakeTalk.Service.ICommonService], Lifetime = Autofac.Core.Lifetime.CurrentScopeLifetime, Sharing = Shared, Ownership = OwnedByLifetimeScope ---> 激活特定注册时出错.有关详细信息，请参阅内部异常。注册：Activator = Repository1 (ReflectionActivator), Services = [MakeTalk.Data.Infrastructure.IRepository1[[MakeTalk.Model.ExhibitionRequestStatus, MakeTalk.Model, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]], Lifetime = Autofac.Core.Lifetime.CurrentScopeLifetime, Sharing = Shared, Ownership = OwnedByLifetimeScope ---> 'MakeTalk.Data.Infrastructure.Repository1[MakeTalk.Model.ExhibitionRequestStatus]' can be found with the constructor finder 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder'. (See inner exception for details.) (See inner exception for details.) ---> Autofac.Core.DependencyResolutionException: An error occurred during the activation of a particular registration. See the inner exception for details. Registration: Activator = Repository1 (ReflectionActivator) 类型没有构造函数，Services = [MakeTalk.Data.Infrastructure.IRepository1[[MakeTalk.Model.ExhibitionRequestStatus, MakeTalk.Model, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]], Lifetime = Autofac.Core.Lifetime.CurrentScopeLifetime, Sharing = Shared, Ownership = OwnedByLifetimeScope ---> No constructors on type 'MakeTalk.Data.Infrastructure.Repository1[MakeTalk.Model.ExhibitionRequestStatus] ' 可以通过构造函数查找器 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder' 找到。（有关详细信息，请参阅内部异常。）---> Autofac.Core.DependencyResolutionException：'MakeTalk.Data.Infrastructure.Repository1[MakeTalk.Model.ExhibitionRequestStatus]' can be found with the constructor finder 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder'. at Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance(IComponentContext context, IEnumerable1 参数类型上没有构造函数）在 Autofac.Core.Resolving.InstanceLookup.Activate（IEnumerable1 parameters) --- End of inner exception stack trace --- at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable1 参数）在 Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare（Guid id，Func1 creator) at Autofac.Core.Resolving.InstanceLookup.Execute() at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable1 参数）在 Autofac.Core.Activators.Reflection.ConstructorParameterBinding.Instantiate() 在 Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance（IComponentContext 上下文，IEnumerable1 parameters) at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable1 参数） --- 内部异常堆栈跟踪结束 --- 在 Autofac.Core.Resolving.InstanceLookup.Activate（IEnumerable1 parameters) at Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare(Guid id, Func1 创建者）在 Autofac.Core.Resolving.InstanceLookup.Execute() 在 Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance（ISharingLifetimeScope currentOperationScope，IComponentRegistration 注册，IEnumerable1 parameters) at Autofac.Core.Resolving.ResolveOperation.Execute(IComponentRegistration registration, IEnumerable1 参数）在 Autofac.ResolutionExtensions.TryResolveService（IComponentContext 上下文，服务服务，IEnumerable1 parameters, Object& instance) at Autofac.ResolutionExtensions.ResolveOptionalService(IComponentContext context, Service service, IEnumerable1 参数）在 Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService（IServiceProvider sp，类型类型，类型 requiredBy，布尔 isDefaultParameterRequired）在 lambda_method（闭包，IServiceProvider，对象 []）在 Microsoft.AspNetCore.Mvc.Controllers.ControllerActivatorProvider.c__DisplayClass4_0.b__0(ControllerContext controllerContext) 在 Microsoft.AspNetCore.Mvc.Controllers.ControllerFactoryProvider.c__DisplayClass5_0.g__CreateController|0(ControllerContext controllerContext) 在 Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next（状态&下一个，范围&范围，对象&状态，布尔& isCompleted）在 Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync() 在 Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter() 在 Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow（ResourceExecutedContext 上下文）在 Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next（状态&下一个，范围&范围，对象&状态，布尔& isCompleted）在 Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync() 在 Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync() 在 Microsoft.AspNetCore.Routing.EndpointMiddleware.Invoke(HttpContext httpContext) 在 Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke(HttpContext httpContext) 在 Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext 上下文)

【问题讨论】：

标签： c# asp.net-core autofac asp.net-core-webapi

【解决方案1】：

如果您查看错误消息，您可以看到这个

无法使用构造函数查找器Autofac.Core.Activators.Reflection.DefaultConstructorFinder 找到类型为MakeTalk.Data.Infrastructure.Repository1[MakeTalk.Model.ExhibitionRequestStatus] 的构造函数。

这意味着 Autofac 在类型 Repository<T> 上找不到构造函数。如果您查看此类型，则构造函数被标记为protected，这意味着 Autofac 无法访问它。

要修复此错误，您必须将构造函数更改为 public

【讨论】：