无法访问已释放的对象. .NET 核心

Question

我在这一行收到此错误：

var removeRole = await _userManager.RemoveFromRolesAsync(applicationUser, roles);

这是代码：

public async Task SaveClient(UserViewModel viewModel)
{
try
{
var applicationUser = await DbSet.SingleOrDefaultAsync(x => x.Id == viewModel.Id && !x.Deleted);
if (applicationUser == null) throw new Exception("User not found. ");
var roles = await _userManager.GetRolesAsync(applicationUser);
if (!(await _userManager.IsInRoleAsync(applicationUser, viewModel.Role)))
{
var removeRole = await _userManager.RemoveFromRolesAsync(applicationUser, roles);
var addRole = await _userManager.AddToRoleAsync(applicationUser, viewModel.Role);
if (viewModel.Role.Equals("Agente") && applicationUser.AgentId == null)
viewModel.AgentId = "A" + new Random().Next(999) + new Random().Next(999);
}
Mapper.Map(viewModel, applicationUser);
await Edit(applicationUser);
// return Task.CompletedTask;
}
catch (Exception ex)
{
throw new Exception(ex.Message + " User not found. ");
}
}

我已经尝试在"var applicationUser"行上"使用"，但仍然没有运气。

有什么帮助吗？

这是我的创业类服务：

public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
services.AddIdentity<ApplicationUser, IdentityRole>(config => {
config.SignIn.RequireConfirmedEmail = true;
}).AddEntityFrameworkStores<ApplicationDbContext>()
.AddDefaultTokenProviders();
// Add application services.
services.AddTransient<IEmailSender, EmailSender>();
services.AddTransient<IUserRepository, UserRepository>();
services.AddTransient<IInvestmentRepository, InvestmentRepository>();
services.AddTransient<IProjectRepository, ProjectRepository>();
services.AddTransient<IPortfolioRepository, PortfolioRepository>();
services.AddTransient<IHttpContextAccessor, HttpContextAccessor>();
services.AddTransient<IPaypalRepository, PaypalRepository>();
services.AddTransient<IStripeRepository, StripeRepository>();
services.AddTransient<IOrderRepository, OrderRepository>();
services.AddTransient<IComissionRepository, ComissionRepository>();
services.AddTransient<IWithdrawRepository, WithdrawRepository>();
services.AddTransient<IDepositRepository, DepositRepository>();
services.AddAutoMapper();
services.AddDistributedMemoryCache();
services.AddSession();
services.AddCors();
services.AddMvc();
}

Answer 1

我终于通过更改来修复它：

var applicationUser = await DbSet.SingleOrDefaultAsync(x => x.Id == viewModel.Id && !x.Deleted);
if (applicationUser == null) throw new Exception("User not found. ");

对此：

var applicationUser = _userManager.FindByIdAsync(viewModel.Id).Result;
if (applicationUser == null || applicationUser.Deleted) throw new Exception("User not found. ");

也从使用async/await切换到Result。

这是整个代码：

public Task SaveClient(UserViewModel viewModel)
{
try
{
var applicationUser = _userManager.FindByIdAsync(viewModel.Id).Result;
if (applicationUser == null || applicationUser.Deleted) throw new Exception("User not found. ");
var role = _userManager.GetRolesAsync(applicationUser).Result.FirstOrDefault();
if (role != viewModel.Role)
{
var removeRole = _userManager.RemoveFromRoleAsync(applicationUser, role).Result;
var addRole = _userManager.AddToRoleAsync(applicationUser, viewModel.Role).Result;
if (viewModel.Role.Equals("Agente") && applicationUser.AgentId == null)
viewModel.AgentId = "A" + new Random().Next(999) + new Random().Next(999);
}
Mapper.Map(viewModel, applicationUser);
Edit(applicationUser);
return Task.CompletedTask;
}
catch (Exception ex)
{
throw new Exception(ex.Message + " User not found. ");
}
}

我希望这可以帮助那些在另一篇文章中没有找到答案的人。