InvalidOperationException：尝试激活“DocumentController”时无法解析“IDocumentService”类型的服务

Question

现在我正在开发 Web api Asp.net 核心，但我对 DI 感到困惑。 当我尝试向我的 api 发送请求时，出现此错误

我使用 Ninject，我认为我对此有疑问 GitLab 和我的项目https://gitlab.com/ValeriiDmytryshyn/sharedocument

启动文件可能有问题

public class Startup
{
    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 void ConfigureServices(IServiceCollection services)
    {
        services.AddDbContext<DocumentContext>
            (options => options.UseSqlServer(Configuration["ConnectionStrings:DefaultConnection"]));

        services.AddControllers();
        var mappingConfig = new MapperConfiguration(mc =>
        {
            mc.AddProfile(new AutomapperProfile());
        });

        IMapper mapper = mappingConfig.CreateMapper();
        services.AddSingleton(mapper);

        services.AddMvc();

        NinjectModule ninjectModule = new NinjModule();
        NinjectModule serviceModule = new ServiceModule(Configuration["ConnectionStrings:DefaultConnection"]);
        var kernel = new StandardKernel(ninjectModule, serviceModule);
        DependencyResolver.SetResolver(new NinjectDependencyResolver(kernel));
    }


    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        app.UseDeveloperExceptionPage();

        app.UseHttpsRedirection();
        app.UseStaticFiles();

        app.UseRouting();

        app.UseAuthentication();
        app.UseAuthorization();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllerRoute(
                name: "default",
                pattern: "{controller=Home}/{action=Index}/{id?}");
        });
    }
}

Answer 1

看来您需要为依赖注入注册服务才能解析您的类。

您必须将所有注入的类注册为 Singleton 或 Transient。这是在 startup.cs 中尝试的示例

services.AddTransient<IDocumentService , DocumentService>();

有关详细信息，请参阅文档 https://docs.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection?view=aspnetcore-5.0