我收到一个错误：
在上一个操作完成之前，在此上下文上启动了第二个操作
当我尝试使用AddToRoleAsync函数添加用户角色时。我看到很多帖子说失踪等待，但一切都是正确的。下面是我正在使用的代码。
public async Task<IActionResult> RegisterCustomer(UserForRegisterCustomerDto userForRegisterCustomerDto)
{
userForRegisterCustomerDto.UserName = userForRegisterCustomerDto.Email;
var userToCreate = _mapper.Map<Users>(userForRegisterCustomerDto);
var userVehicleToCreate = _mapper.Map<CustomerVehicles>(userForRegisterCustomerDto.CustomerVehicles);
var result = await _userManager.CreateAsync(userToCreate, userForRegisterCustomerDto.Password);
var userToReturn = _mapper.Map<UserForDetailedDto>(userToCreate);
if (result.Succeeded)
{
var currentUser = await _userManager.FindByEmailAsync(userForRegisterCustomerDto.Email);
await _userManager.AddToRoleAsync(currentUser, "Customer");
userVehicleToCreate.UserId = currentUser.Id;
_repo.Add(userVehicleToCreate);
if (await _repo.SaveAll())
{
string confirmationToken = await _userManager.GenerateEmailConfirmationTokenAsync(currentUser);
//ConfirmEmail(currentUser.Id, confirmationToken);
return Ok(userToReturn);
}
}
return BadRequest(result.Errors);
}
我的创业.cs是
services.AddDbContext<DataContext>(x => x.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")), ServiceLifetime.Transient);
添加 ServiceLifetime.Transient 无法解决此问题。 请指教。
错误是：
Microsoft.EntityFrameworkCore.Query[10100]
An exception occurred while iterating over the results of a query for context type 'Demo.API.Models.DataContext'.
System.InvalidOperationException: A second operation started on this context before a previous operation completed. This is usually caused by
different threads using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
at Microsoft.EntityFrameworkCore.Internal.ConcurrencyDetector.EnterCriticalSection()
at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
System.InvalidOperationException: A second operation started on this context before a previous operation completed. This is usually caused by different threads using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
at Microsoft.EntityFrameworkCore.Internal.ConcurrencyDetector.EnterCriticalSection()
at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
An unhandled exception has occurred while executing the request.
System.InvalidOperationException: A second operation started on this context before a previous operation completed. This is usually caused by different threads using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
at Microsoft.EntityFrameworkCore.Internal.ConcurrencyDetector.EnterCriticalSection()
at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleOrDefaultAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleOrDefaultAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)
at Microsoft.AspNetCore.Identity.EntityFrameworkCore.UserStore`9.IsInRoleAsync(TUser user, String normalizedRoleName, CancellationToken cancellationToken)
at Microsoft.AspNetCore.Identity.UserManager`1.AddToRoleAsync(TUser user, String role)
at Demo.API.Controllers.AuthController.RegisterCustomer(UserForRegisterCustomerDto userForRegisterCustomerDto) in F:testDemoDemo.APIControllersAuthController.cs:line 66
at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.TaskOfIActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Awaited|12_0(ControllerActionInvoker invoker, ValueTask`1 actionResultValueTask)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeNextActionFilterAsync>g__Awaited|10_0(ControllerActionInvoker invoker,
Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task
lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
然后添加这个
services.AddDbContext<DataContext>(x => x.UseSqlServer(Configuration
.GetConnectionString("DefaultConnection")).UseQueryTrackingBehaviour(QueryTrackingBehavior.NoTracking));
问题来自您创建模型的方式。
解决方案：处理 NULL 字段并检查模型。
此外，如果您对登录名、用户名、登录管理器等字段或与_Layout视图中的类和模型相关的其他内容进行操作，请检查它们......错误从他们那里升起。