Question

我收到此错误

System.ObjectDisposedException
  HResult=0x80131622
  Message=Cannot access a disposed object. A common cause of this error is disposing a context that was resolved from dependency injection and then later trying to use the same context instance elsewhere in your application. This may occur if you are calling Dispose() on the context, or wrapping the context in a using statement. If you are using dependency injection, you should let the dependency injection container take care of disposing context instances.
  Source=Microsoft.EntityFrameworkCore
  StackTrace:
   at Microsoft.EntityFrameworkCore.Internal.ConcurrencyDetector.AsyncDisposer.Dispose()
   at Microsoft.EntityFrameworkCore.Query.Internal.AsyncLinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.<MoveNext>d__5.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<ExecuteSingletonAsyncQuery>d__21`1.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.AspNetCore.Identity.UserManager`1.<FindByNameAsync>d__78.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.AspNetCore.Identity.UserValidator`1.<ValidateUserName>d__6.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Identity.UserValidator`1.<ValidateAsync>d__5.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.AspNetCore.Identity.UserManager`1.<ValidateUserAsync>d__172.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.AspNetCore.Identity.UserManager`1.<CreateAsync>d__74.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.AspNetCore.Identity.UserManager`1.<CreateAsync>d__79.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at EmployeeController.<Create>d__3.MoveNext() in Controllers\EmployeeController.cs:line 31

以下代码

public class EmployeeController : Controller
{
    private readonly UserManager<Employee> userManager;
    public EmployeeController(UserManager<Employee> userManager)
    {
        this.userManager = userManager;
    }

    public ActionResult<string> Get()
    {
        return "Test Employee";
    }

    [HttpPost("Create")]
    public async void Create([FromBody]string employee)
    {
        var user = new Employee { UserName = "test@gmail.com", Email = "test@gmail.com" };
        var d = await userManager.CreateAsync(user, "1234567");
    }
}

Startup.cs

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<ApplicationDbContext>(options =>
         options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

        services.AddIdentity<Employee, IdentityRole>(opts =>
       {
           opts.Password.RequireDigit = false;
           opts.Password.RequireLowercase = false;
           opts.Password.RequireUppercase = false;
           opts.Password.RequireNonAlphanumeric = false;
           opts.Password.RequiredLength = 7;
           opts.User.RequireUniqueEmail = true;

       }).AddEntityFrameworkStores<ApplicationDbContext>().AddDefaultTokenProviders();

        services.AddAuthentication(opts =>
        {
            opts.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;
            opts.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
            opts.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
        }).AddJwtBearer(cfg =>
        {
            cfg.RequireHttpsMetadata = false;
            cfg.SaveToken = true;
            cfg.TokenValidationParameters = new TokenValidationParameters()
            {
                // standard configuration
                ValidIssuer = Configuration["Auth:Jwt:Issuer"],
                ValidAudience = Configuration["Auth:Jwt:Audience"],
                IssuerSigningKey = new SymmetricSecurityKey(
                Encoding.UTF8.GetBytes(Configuration["Auth:Jwt:Key"])),
                ClockSkew = TimeSpan.Zero,

                // security switches
                RequireExpirationTime = true,
                ValidateIssuer = true,
                ValidateIssuerSigningKey = true,
                ValidateAudience = true
            };
        });


            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
    }

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

        app.UseHttpsRedirection();
        app.UseAuthentication();
        app.UseMvc();
    }
}

我需要在DI中注册一些内容吗？我的印象是AddEntityFrameworkStores<ApplicationDbContext>()就足够了。

Answer 1

您是async void受害者：

[HttpPost("Create")]
public async void Create([FromBody]string employee)
{
    var user = new Employee { UserName = "test@gmail.com", Email = "test@gmail.com" };
    var d = await userManager.CreateAsync(user, "1234567");
}

您正在调度一个等待不的异步操作，并且上下文将在await context.SaveChangesAsync()中的CreateAsync之前处理。

快速，明显的解决方案：

[HttpPost("Create")]
public async Task Create([FromBody]string employee)
{
    var user = new Employee { UserName = "test@gmail.com", Email = "test@gmail.com" };
    var d = await userManager.CreateAsync(user, "1234567");
}

但是，您应该始终从Action返回IActionResult。这样可以更轻松地更改响应代码并显示您的意图：

[HttpPost("Create")]
public async Task<IActionResult> Create([FromBody]string employee)
{
    var user = new Employee { UserName = "test@gmail.com", Email = "test@gmail.com" };
    var d = await userManager.CreateAsync(user, "1234567");

    if (d == IdentityResult.Success)
    {
        return Ok();
    }
    else 
    {
        return BadRequest(d);
    }
}

无法访问已处置的对象Asp.net Identity Core

1 个答案: