.NET Core MVC 项目中的 Autofac 属性注入

Question

我有一个带有ILol 类型属性和Lol 类实现ILol 的控制器。

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 Property injection 与 Autofac 一起使用（我的 Startup 课程的一部分）：

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。虽然构造函数注入工作正常。

Answer 1

您必须指定需要在哪些控制器中使用属性注入：

 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，只需在构建器中注册更多类型 PropertiesAutowired()。

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);
    }