ASP.NET Core Identity UserManager<ApplicationUser> - 错误没有为此对象定义无参数构造函数

Question

我只是想开发一个用于身份验证和授权的示例项目，并遵循link

ASP.NET Core MVC: Authentication and Role Based Authorisation with Identity

当运行代码时，我得到一个错误

堆栈跟踪：

[MissingMethodException: No parameterless constructor defined for this object.] System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0
System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +119
System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +247 System.Activator.CreateInstance(Type type, Boolean nonPublic) +83 System.Activator.CreateInstance(Type type) +11 System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +55

[InvalidOperationException: An error occurred when trying to create a controller of type 'SampleAuthProject.Controllers.HomeController'. Make sure that the controller has a parameterless public constructor.] System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +178
System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +76
System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +88
System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +194 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +50
System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +48
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +16
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +103 System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +48 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +159

我认为这个错误是由于 DI。

所以在我的startup.cs中包含

public void Configuration(IAppBuilder app)
{
    ConfigureAuth(app);
}
public Startup()
{
    var builder = new ConfigurationBuilder();
    Configurations = builder.Build();
}
public IConfigurationRoot Configurations { get; }
public void ConfigureServices(IServiceCollection services)
{
    try
    {
        services.AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(Configurations.GetConnectionString("DefaultConnection")));

        services.AddIdentity<ApplicationUser, IdentityRole>()
            .AddEntityFrameworkStores<ApplicationDbContext>()
            .AddDefaultTokenProviders();

        services.AddMvc();
        services.AddTransient<UserManager<ApplicationUser>>();
        services.AddTransient<ApplicationDbContext>();
    }
    catch (Exception ex)
    {
        throw ex;
    }

}
public void Configure(IApplicationBuilder app,
               IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    app.UseIdentity();
}

我的家庭控制器是

 [Microsoft.AspNetCore.Authorization.Authorize]
public class HomeController : Controller
{
    private readonly UserManager<ApplicationUser> userManager;

    public HomeController(UserManager<ApplicationUser> userManager)
    {
        this.userManager = userManager;
    }
    [Microsoft.AspNetCore.Authorization.Authorize(Roles = "User")]
    public ActionResult Index()
    {
        //userManager=new UserManager<ApplicationUser>();
        string userName =  userManager.GetUserName(System.Security.Claims.ClaimsPrincipal.Current);
        return View("Index",userName);
    }       
}

Answer 1

您似乎在尝试混合框架版本。

Startup 同时使用了 IAppBuilder，它来自 asp。net-mvc-5 和 IApplicationBuilder，这是最近的 asp.net-core.

另外，异常消息

No parameterless constructor defined for this object

通常与从 MVC 5 和 Web.Api 2.*

返回的模糊消息相关联

这基本上意味着该项目的依赖项注入框架不知道身份依赖项，这就是它无法将依赖项注入控制器的原因。

要么确保该项目实际上是一个 asp.net-core 项目，以便能够使用 asp.net-core-身份

Introduction to Identity on ASP.NET Core

或者使用正确版本的 MVC 5 身份框架。

Introduction to ASP.NET Identity

ASP.NET Core Identity UserManager<ApplicationUser> - 错误没有为此对象定义无参数构造函数

ASP.NET Core Identity UserManager<ApplicationUser> -Error No parameterless constructor defined for this object

c#

dependency-injection

asp.net-core

asp.net-core-identity