asp.net-mvc - 多个用户创建用户时修改了 automapper 错误集合

Question

我收到以下错误，并且仅当多个用户点击同一个按钮时才会出现此错误。任何帮助/想法将不胜感激:

System.InvalidOperationException: Collection was modified; enumeration operation may not execute. Generated: Wed, 10 Jun 2015 07:29:06 GMT

AutoMapper.AutoMapperMappingException:

Mapping types: User -> User ApplicationSecurityManager.Service.User -> ApplicationSecurityManager.Models.User

Destination path: User

Source value: ApplicationSecurityManager.Service.User ---> System.InvalidOperationException: Collection was modified; enumeration operation may not execute. at System.Collections.Generic.List1.Enumerator.MoveNextRare() at
AutoMapper.TypeMap.<get_AfterMap>b__1(Object src, Object dest) at
AutoMapper.Mappers.TypeMapObjectMapperRegistry.PropertyMapMappingStrategy.Map(ResolutionContext
context, IMappingEngineRunner mapper) at
AutoMapper.Mappers.TypeMapMapper.Map(ResolutionContext context,
IMappingEngineRunner mapper) at
AutoMapper.MappingEngine.AutoMapper.IMappingEngineRunner.Map(ResolutionContext
context) --- End of inner exception stack trace --- at
AutoMapper.MappingEngine.AutoMapper.IMappingEngineRunner.Map(ResolutionContext
context) at AutoMapper.MappingEngine.Map[TDestination](Object
source, Action1 opts) at ApplicationSecurityManager.UserManager.LoadUser(String username) at ApplicationSecurityManager.UserManager.get_AuthenticatedUser() at ApplicationSecurityManager.UserManager.IsAuthenticated() at ApplicationSecurityManager.Infrastructure.ApplicationSecurityAttribute.OnAuthorization(AuthorizationContext filterContext) at System.Web.Mvc.ControllerActionInvoker.InvokeAuthorizationFilters(ControllerContext controllerContext, IList1 filters, ActionDescriptor actionDescriptor)
at
System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass25.<BeginInvokeAction>b__1e(AsyncCallback
asyncCallback, Object asyncState) at
System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult1.Begin(AsyncCallback callback, Object state, Int32 timeout) at System.Web.Mvc.Async.AsyncResultWrapper.Begin[TResult](AsyncCallback callback, Object state, BeginInvokeDelegate beginDelegate, EndInvokeDelegate1 endDelegate, Object tag, Int32 timeout) at
System.Web.Mvc.Async.AsyncResultWrapper.Begin[TResult](AsyncCallback
callback, Object state, BeginInvokeDelegate beginDelegate,
EndInvokeDelegate1 endDelegate, Object tag) at System.Web.Mvc.Controller.<>c__DisplayClass1d.b__17(AsyncCallback asyncCallback, Object asyncState) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult1.Begin(AsyncCallback
callback, Object state, Int32 timeout) at
System.Web.Mvc.Async.AsyncResultWrapper.Begin[TResult](AsyncCallback
callback, Object state, BeginInvokeDelegate beginDelegate,
EndInvokeDelegate1 endDelegate, Object tag, Int32 timeout) at System.Web.Mvc.Controller.BeginExecuteCore(AsyncCallback callback, Object state) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult1.Begin(AsyncCallback
callback, Object state, Int32 timeout) at
System.Web.Mvc.Async.AsyncResultWrapper.Begin[TResult](AsyncCallback
callback, Object state, BeginInvokeDelegate beginDelegate,
EndInvokeDelegate1 endDelegate, Object tag, Int32 timeout) at System.Web.Mvc.Async.AsyncResultWrapper.Begin(AsyncCallback callback, Object state, BeginInvokeDelegate beginDelegate, EndInvokeDelegate endDelegate, Object tag) at System.Web.Mvc.Controller.BeginExecute(RequestContext requestContext, AsyncCallback callback, Object state) at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.b__2(AsyncCallback asyncCallback, Object asyncState) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult1.Begin(AsyncCallback
callback, Object state, Int32 timeout) at
System.Web.Mvc.Async.AsyncResultWrapper.Begin[TResult](AsyncCallback
callback, Object state, BeginInvokeDelegate beginDelegate,
EndInvokeDelegate1 endDelegate, Object tag, Int32 timeout) at System.Web.Mvc.Async.AsyncResultWrapper.Begin(AsyncCallback callback, Object state, BeginInvokeDelegate beginDelegate, EndInvokeDelegate endDelegate, Object tag) at System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

这是我认为后映射是问题的构造函数，但是在调试时我没有收到错误。

Public Sub New(environmentCode As String, applicationCode As String)
    MyBase.New(environmentCode, applicationCode)

    SOBaseUrl = System.Configuration.ConfigurationManager.AppSettings(Enums.AppSettingKeys.SOBaseUrl.ToString())
    If Not String.IsNullOrEmpty(SOBaseUrl) Then
        SOBaseUrl = SOBaseUrl.TrimEnd("/")
    End If

    'Setup mapping.
    Mapper.CreateMap(Of Service.User, Models.User)() _
        .ForMember(Function(dest As Models.User) dest.ENumber, Sub(opt) opt.MapFrom(Function(src As Service.User) src.INumber)) _
        .AfterMap(Sub(src As Service.User, dest As Models.User)

            dest.Groups = New List(Of String)

            Using service = ApplicationSecurityManager.Service.Factory.GetService()

                Dim applicationPermissions = service.LoadPermissionsForUser(dest.Username, MyBase.EnvironmentCode)

                If (Not applicationPermissions Is Nothing AndAlso applicationPermissions.Any(Function(x) x.Code = MyBase.ApplicationCode)) Then

                    dest.Groups = applicationPermissions.Single(Function(x) x.Code = MyBase.ApplicationCode).GroupNames.ToList()

                End If

            End Using

        End Sub)

依赖注入(inject)映射:

container.RegisterType(Of IUserManager, UserManager)(New PerThreadLifetimeManager(),
    New InjectionConstructor(
      ConfigurationManager.AppSettings(Common.Enums.AppSettingKeys.Environment.ToString()),
      ConfigurationManager.AppSettings(Common.Enums.AppSettingKeys.ApplicationCode.ToString()))
    )

在 saveUserResponse ，错误被抛出。

 Public Function Create(user As Common.Models.User, approve As Boolean) As SO.Common.Models.User Implements IUserProvider.Save

    Dim saveUserResponse = UserManager.SaveUser(Mapper.Map(Of ApplicationSecurityManager.Service.User)(user))

    If Not String.IsNullOrEmpty(saveUserResponse.ErrorMessage) Then

        'The Security system returned an error.

        Throw New Exception("Security Service returned error: " & saveUserResponse.ErrorMessage)

    End If

    'Return the username.
    Return Mapper.Map(Of Common.Models.User)(saveUserResponse.User)

End Function

Answer 1

当多个用户在映射的 AfterMap() 方法中修改同一个 user.Groups 集合时，就会出现这种情况。为避免这种情况，请锁定正在处理集合的代码。例如:

'class level object
private object _myLock = New object()

'Setup mapping.
Mapper.CreateMap(Of Service.User, Models.User)() _
    .ForMember(Function(dest As Models.User) dest.ENumber, Sub(opt) opt.MapFrom(Function(src As Service.User) src.INumber)) _
    .AfterMap(Sub(src As Service.User, dest As Models.User)
                  SyncLock _myLock
                      dest.Groups = New List(Of String)

                      Using service = ApplicationSecurityManager.Service.Factory.GetService()

                          Dim applicationPermissions = service.LoadPermissionsForUser(dest.Username, MyBase.EnvironmentCode)

                          If (Not applicationPermissions Is Nothing AndAlso applicationPermissions.Any(Function(x) x.Code = MyBase.ApplicationCode)) Then

                              dest.Groups = applicationPermissions.Single(Function(x) x.Code = MyBase.ApplicationCode).GroupNames.ToList()

                          End If

                      End Using
                  End SyncLock

              End Sub)