asp.net-mvc - .NET Core MVC项目中的Autofac属性注入(inject)

Question

我有一个具有 ILol 类型属性的 Controller 和实现 ILol 的 Lol 类。

public class UniversityController : Controller
{
    public ILol Lol { get; set; }

    public IActionResult Index()
    {
        ViewData["Header"] = "Hello, world!";
        ViewData["NullCheck"] = Lol == null ? "It's null" : Lol.GetLol();

        return View();
    }
}

我尝试以这种方式将属性注入(inject)与Autofac结合使用(我的Startup类的一部分):

public IContainer ApplicationContainer { get; private set; }

    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public IServiceProvider ConfigureServices(IServiceCollection services)
    {
        services.Configure<CookiePolicyOptions>(options =>
        {
            // This lambda determines whether user consent for non-essential cookies is needed for a given request.
            options.CheckConsentNeeded = context => true;
            options.MinimumSameSitePolicy = SameSiteMode.None;
        });

        // Dependency resolving.
        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

        ContainerBuilder builder = new ContainerBuilder();

        builder.RegisterType<Lol>().As<ILol>().PropertiesAutowired().InstancePerLifetimeScope();
        builder.Populate(services);

        IContainer container = builder.Build();

        ApplicationContainer = container;

        return new AutofacServiceProvider(container);
    }

它不起作用。该属性在运行时为空。尽管构造函数注入(inject)工作正常。

Answer 1

您必须指定哪些 Controller 需要使用属性注入(inject):

 var controllersTypesInAssembly = typeof(Startup).Assembly.GetExportedTypes()
            .Where(type => typeof(ControllerBase).IsAssignableFrom(type)).ToArray();
 builder.RegisterTypes(controllersTypesInAssembly).PropertiesAutowired();

并调用AddControllersAsServices():

services.AddMvc()
.SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
.AddControllersAsServices();

如果您需要注册属性注入(inject)，只需在构建器中注册更多类型 PropertiesAutowired() 即可。

ConfigureServices 将如下所示:

public IServiceProvider ConfigureServices(IServiceCollection services)
    {
        services.Configure<CookiePolicyOptions>(options =>
        {
            // This lambda determines whether user consent for non-essential cookies is needed for a given request.
            options.CheckConsentNeeded = context => true;
            options.MinimumSameSitePolicy = SameSiteMode.None;
        });

        // Dependency resolving.
        services.AddMvc()
        .SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
        .AddControllersAsServices();

        ContainerBuilder builder = new ContainerBuilder();
        builder.Populate(services);//Autofac.Extensions.DependencyInjection

        builder.RegisterType<Lol>().As<ILol>().PropertiesAutowired().InstancePerLifetimeScope();
        builder.Populate(services);

        var controllersTypesInAssembly = typeof(Startup).Assembly.GetExportedTypes()
            .Where(type => typeof(ControllerBase).IsAssignableFrom(type)).ToArray();
        builder.RegisterTypes(controllersTypesInAssembly).PropertiesAutowired();

        IContainer container = builder.Build();

        ApplicationContainer = container;

        return new AutofacServiceProvider(container);
    }