具有Autofac的通用DBContext注入

Question

我正在尝试通过Autofac将DbContext实例注册并注入到我的组件中。我知道我目前使用的方法可以改进，我也在寻找有关实现方法的想法。目前，我只是在研究泛型的想法，并试图使其通用，但它抛出了此异常。 Autofac是否有可能产生多个线程以注入组件？

System.Threading.Tasks.TaskCanceledException: A task was canceled.
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenDbConnectionAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenDbConnectionAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenAsync(CancellationToken cancellationToken, Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(DbContext _, Boolean result, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleOrDefaultAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleOrDefaultAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)
   at UserService.Repositories.UserRepository.FindByIdAsync(String id) in /Users/ryanr/Documents/invoicer-backend-microservices/src/UserService/Repositories/UserRepository.cs:line 31
   at UserService.Queries.Handlers.GetUserByIDQueryHandler.Handle(GetUserByIDQuery query) in /Users/ryanr/Documents/invoicer-backend-microservices/src/UserService/Queries/Handlers/GetUserByIDQueryHandler.cs:line 19
   at UserService.Controllers.UsersController.GetUserById(GetUserByIDQuery query) in /Users/ryanr/Documents/invoicer-backend-microservices/src/UserService/Controllers/UsersController.cs:line 43
   at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.TaskOfIActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Awaited|12_0(ControllerActionInvoker invoker, ValueTask`1 actionResultValueTask)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeNextActionFilterAsync>g__Awaited|10_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

我有一个注册Autofac类型并定义DBContext接口的类库：

    public interface IDbContext<T> where T: class
    {
        DbSet<T> DataSet { get; set; }
    }

用于注册存储库和注入DbContext的Autofac模块

    public class RepositoryModule : Autofac.Module
    {
        public Assembly ExecutingAssembly { get; set; }
        public string ConnectionString { get; set; }

        protected override void Load(ContainerBuilder builder)
        {
            builder.RegisterAssemblyTypes(ExecutingAssembly)
            .Where(t => t.Name.EndsWith("Repository"))
            .AsImplementedInterfaces();

            builder.RegisterAssemblyTypes(ExecutingAssembly)
                .Where(t => t.IsClosedTypeOf(typeof(IDbContext<>)))
                .AsSelf()
                .InstancePerLifetimeScope();

        }
    }

然后解决此问题并将其注入我的UserService（ASP.Net）：

public class UserRepository : IUserRepository
    {
        private readonly UserDBContext _dbContext;
        public UserRepository(UserDBContext dbContext)
        {
            _dbContext = dbContext;
        }


        public async Task<User> FindByIdAsync(string id)
        {
            return await _dbContext.DataSet.FirstOrDefaultAsync(user => user.Id == id);

        }
}

DbContext类

public class UserDBContext : DbContext, IDbContext<User>
    {
        public DbSet<User> DataSet { get; set; }

        public UserDBContext()
        {
        }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer("server=localhost,1434;user id=sa;password=password;database=UserManagement;");
        }

        protected override void OnModelCreating(ModelBuilder builder)
        {
            builder.Entity<User>().HasKey(m => m.Id);
            builder.Entity<User>().ToTable("User");
            base.OnModelCreating(builder);
        }
   }

然后将存储库注入到我的QueryHandler中，这就是使用DBContext的地方：

public class GetUserByIDQueryHandler : IQueryHandler<GetUserByIDQuery, User>
    {
        private IUserRepository _repository;
        public GetUserByIDQueryHandler(IUserRepository repository)
        {
            _repository = repository;
        }

        public async Task<User> Handle(GetUserByIDQuery query)
        {
            return await _repository.FindByIdAsync(query.Id);
        }
    }

其中QueryHandler的解析方式：

var handlers = scope.Resolve<IEnumerable<IQueryHandler<TRequest, TResponse>>>().ToList();

任何帮助将不胜感激！谢谢：）

Answer 1

我认为这与依赖项注入或autofac没有任何关系。查看堆栈跟踪-跟踪顶部显示：

在Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenDbConnectionAsync（Boolean errorsExpected，CancellationToken cancelleToken）]中>

这似乎是连接数据库的问题。检查您的连接字符串并进行快速测试，以确保您可以连接到数据库，而不会浪费autofac或查询处理程序的复杂性。