c# - 此解析操作已结束。 Autofac、Automapper 和 IMemberValueResolver

Question

我对 Autofac 和 Automapper 有疑问。

在我的 WebApi 中，我有这段代码来注册我的类(class):

    public static void Initialize(HttpConfiguration config, IContainer container)
        {
            config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
            _container = container;
        }

        private static IContainer RegisterServices(ContainerBuilder builder)
        {
            //Register your Web API controllers.  
            builder.RegisterApiControllers(Assembly.GetExecutingAssembly());

            builder.RegisterModule<MapperInstaller>();
            builder.RegisterType<VurpEntities>();
            builder.RegisterType<EntityFrameworkUnitOfWork>().As<IUnitOfWork>();

            builder.RegisterType<AppService>().As<IAppService>();
            builder.RegisterType<AppRepository>().As<IAppRepository>();

            builder.RegisterType<BusinessService>().As<IBusinessService>();
            builder.RegisterType<BusinessRepository>().As<IBusinessRepository>();

//...
//all my types are registered here
//...



            //Set the dependency resolver to be Autofac.  
            _container = builder.Build();

            return _container;
        }

我创建了一个 Resolver 来映射我的对象的一个​​特殊字段:

public class ProductTypeResolver : IMemberValueResolver<ProductDto, Product, string, Enumeration.ProductType>
    {
        public ProductType Resolve(ProductDto source, Product destination, string sourceMember, ProductType destMember, ResolutionContext context)
        {
            Enum.TryParse(sourceMember, out destMember);

            return destMember;
        }
    }

我有一个在实体对象中映射 DTO 对象的配置文件:

CreateMap<ProductDto, Product>()
            .ForMember(dest => dest.Category, opt => opt.Ignore())
            .ForMember(dest => dest.Feature, opt => opt.Ignore())
opts.ResolveUsing<ProductTypeResolver, string>(src => src.type));

当我尝试映射对象时 Product p = _mapper.Map<Product>(productDto);我收到错误:

An exception of type 'System.ObjectDisposedException' occurred in Autofac.dll but was not handled in user code

Additional information: This resolve operation has already ended. When registering components using lambdas, the IComponentContext 'c' parameter to the lambda cannot be stored. Instead, either resolve IComponentContext again from 'c', or resolve a Func<> based factory to create subsequent components from.

谁能帮帮我？

Answer 1

我用这个解决了:

    builder.Register(c =>
    {
        //This resolves a new context that can be used later.
        var context = c.Resolve<IComponentContext>();
        var config = context.Resolve<MapperConfiguration>();
        return config.CreateMapper(context.Resolve);
    })
    .As<IMapper>()
    .InstancePerLifetimeScope();