将AutoMapper注入其他层的正确方法是什么？

我读了这个博客post,但是下面的代码导致异常

An exception of type ‘AutoMapper.AutoMapperMappingException’ occurred in AutoMapper.dll but was not handled in user code

尝试在服务层中映射时.

List<StudentViewModel> list2 = _mapper.Map<List<StudentViewModel>>(list);

我的AutoFac配置如下：

public static class DependencyRegistration
{
    public static void Config()
    {
        var builder = new ContainerBuilder();

        builder.RegisterControllers(typeof(MvcApplication).Assembly);


        builder.RegisterType<TypeMapFactory>().As<ITypeMapFactory>();
        builder.RegisterType<ConfigurationStore>().As<ConfigurationStore>().WithParameter("mappers", MapperRegistry.Mappers).SingleInstance();
        builder.Register((ctx, t) => ctx.Resolve<ConfigurationStore>()).As<IConfiguration>().As<IConfigurationProvider>();
        builder.RegisterType<MappingEngine>().As<IMappingEngine>();

        //...
        var container = builder.Build();
        DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
    }
}

解决方法:

似乎您需要使用在容器中注册的IConfiguration对象来创建映射,如下所示：

var configuration = container.Resolve<IConfiguration>();
configuration.CreateMap<Student, StudentViewModel>();

我认为您应该在应用程序开始时执行此操作.

这是在Config方法中配置事物的更好方法(IMO)：

public static void Config()
{
    var configuration_store = new ConfigurationStore(new TypeMapFactory(), MapperRegistry.Mappers);

    var mapping_engine = new MappingEngine(configuration_store);

    configuration_store.CreateMap<Student, StudentViewModel>();

    var builder = new ContainerBuilder();

    builder.RegisterInstance(mapping_engine).As<IMappingEngine>();

    //...
    var container = builder.Build();
    DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
}

在上一个示例中,我假设您的类仅需要访问IMappingEngine(而不是IConfiguration),因为您应该已经在Config方法(或在应用程序启动时使用某些其他配置方法)中设置了所有映射.