当我们调用AccountApiController.Register（）方法时，为什么会发生这种情况？
“消息”：“发生了错误。”，
“ExceptionMessage”：“模型时不能使用上下文 被创造。如果使用上下文，则可能抛出此异常 在OnModelCreating方法内部或者相同的上下文实例 由多个线程同时访问。请注意实例成员 DbContext和相关类不保证是线程 安全“。，
“ExceptionType”： “System.InvalidOperationException”，
“StackTrace”：“
在System.Web.Http.ApiController.d__1.MoveNext（）
---从抛出异常的先前位置开始的堆栈跟踪结束
在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）
在System.Runtime.CompilerServices.TaskAwaiter .HandleNonSuccessAndDebuggerNotification（任务＆gt;任务）
at System.Web.Http.Dispatcher.HttpControllerDispatcher.d__0.MoveNext（）“
答案 0 :(得分：25)
如果connectionString不正确，也会发生此错误。检查connectionString是否有效（没有拼写错误等）。
答案 1 :(得分：23)
问题是我们没有使用MS recommends的工厂模式。
您可以使用Factory实现来获取UserManager的实例 来自OWIN的背景。 ...这是获取实例的推荐方法 每个应用程序请求的UserManager。
因此，“同时由多个线程访问相同的上下文实例”，因为多个请求和线程共享一个DbContext。
以下是正确的。它为每次调用UserManagerFactory函数创建一个新的MyDbContext实例。
UserManagerFactory
= () => new UserManager<IdentityUser>(new UserStore<IdentityUser>(new MyDbContext()));
以下内容不正确。它看起来类似，但不会为每次调用UserManagerFactory创建新实例。这是我们正在使用的，因为我们的网站已经破坏了。
var userStore = new UserStore<IdentityUser>(new MyDbContext());
var userManager = new UserManager<IdentityUser>(userStore);
UserManagerFactory = () => userManager;
答案 2 :(得分：1)
您是否覆盖了OnModelCreating方法？如果是这样，你可以分享它或整个上下文类吗？
如果没有，您应该注意错误信息中的以下内容
或者同时由多个线程访问相同的上下文实例。请注意，DbContext和相关类的实例成员不保证是线程安全的。
如果这没有帮助，您是否使用由Visual Studio创建的未更改的Web API项目？
答案 3 :(得分：0)
我在使用MySQL的多层架构中使用EF Code First并且具有相同的异常，并且在DBContext类结构中使用以下行：
Database.SetInitializer<EntitiesName>(null);
答案 4 :(得分：0)
我同意 Shaun Luttin 的主要回答，但
在我的情况下：部署后出现此错误，我发现原因是在插入SSL证书后使用了Hsts预加载。取消注释此行即可解决重定向，并且可以彻底解决此错误
public MainDialog(ILogger<MainDialog> logger, IBotServices botServices, UserState userState) :
base(nameof(MainDialog))
{ _botServices = botServices;// ?? throw new System.ArgumentNullException(nameof(botServices));
_logger = logger;
_userState = userState;
AddDialog(new ProductIssue($"{nameof(MainDialog)}.fromMain", _botServices, _userState));
AddDialog(new ProductIssue($"{nameof(Confirm)}.fromConfirm", _botServices, _userState));
AddDialog(new ProductIssue($"{ nameof(Resolution)}.resolution", _botServices, _userState));
AddDialog(new PurchaseFlow(_userState));
AddDialog(new Resolution( _userState));
AddDialog(new Confirm(_botServices,_userState));
AddDialog(new ChoicePrompt($"{nameof(MainDialog)}.issue"));
AddDialog(new TextPrompt($"{nameof(MainDialog)}.callDialog"));
AddDialog(new TextPrompt($"{nameof(MainDialog)}.number", ValidationAsync));
AddDialog(new WaterfallDialog($"{nameof(MainDialog)}.mainFlow", new WaterfallStep[]
{
MoblieNumberAsync,
ChoiceCardStepAsync,
ShowCardStepAsync,
CallingDialogsAsync
}));
AddDialog(new TextPrompt(nameof(TextPrompt)));
InitialDialogId = $"{nameof(MainDialog)}.mainFlow";
}
private async Task<DialogTurnResult> MoblieNumberAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
{
stepContext.Values[UserInfo] = new UserInput();
var options = new PromptOptions()
{
Prompt = MessageFactory.Text("Kindly enter your 10 digit mobile number without any spaces, dashes and country code. We will be sending an OTP later to this number "),
RetryPrompt = MessageFactory.Text("Incorrect mobile number entered. Please only enter the 10 digits of your mobile without any spaces, dashes and country code.")
};
return await stepContext.PromptAsync($"{nameof(MainDialog)}.number", options, cancellationToken);
}
private async Task<DialogTurnResult> ChoiceCardStepAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
{
var userStateAccessors = _userState.CreateProperty<UserInput>(nameof(UserInput));
var userinfo = await userStateAccessors.GetAsync(stepContext.Context, () => new UserInput());
userinfo.phone_no = (string)stepContext.Result;
CustomerDetails customerDetails = new CustomerDetails();
//API-Get Customer Details from CRM
try
{
BotAPIBLL botApiBLL = new BotAPIBLL();
var response = botApiBLL.GetCustomerDetail(stepContext.Context.Activity.Text);
customerDetails = JsonConvert.DeserializeObject<CustomerDetails>(response);
}
catch(Exception ex)
{
}
await stepContext.Context.SendActivityAsync(MessageFactory.Text("Fetching your details from our systems. This may take a moment"), cancellationToken);
if (customerDetails.D != null && !string.IsNullOrEmpty(customerDetails.D.TelNumber) && !string.IsNullOrEmpty(customerDetails.D.NameFirst))
{
DbConnection dbConnection = new DbConnection();
dbConnection.SaveCutomerInfo(customerDetails);
userinfo.Name = customerDetails.D.NameFirst;
var options = new PromptOptions()
{
Prompt = MessageFactory.Text("Welcome " + customerDetails.D.NameFirst + ", How can we serve you ? "),
RetryPrompt = MessageFactory.Text("That was not a valid choice, please select a option between 1 to 5."),
Choices = GetChoices(),
Style = ListStyle.HeroCard
};
return await stepContext.PromptAsync($"{nameof(MainDialog)}.issue", options, cancellationToken);
}
else
{
var options = new PromptOptions()
{
Prompt = MessageFactory.Text("Welcome Guest_" + userinfo.phone_no + ", How can we serve you ? "),
RetryPrompt = MessageFactory.Text("That was not a valid choice, please select a option between 1 to 5."),
Choices = GetChoices(),
Style = ListStyle.HeroCard
};
return await stepContext.PromptAsync($"{nameof(MainDialog)}.issue", options, cancellationToken);
}
}
private async Task<DialogTurnResult> ShowCardStepAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
{
var userinfo = (UserInput)stepContext.Values[UserInfo];
userinfo.choiceselected = ((FoundChoice)stepContext.Result).Value;
var attachments = new List<Attachment>();
var reply = MessageFactory.Text("");
var user_choice = ((FoundChoice)stepContext.Result).Value;
switch (user_choice)
{
case "Product issue":
reply.Attachments.Add(Cards.CreateAdaptiveCardAttachment3());
break;
case "Register Product":
reply.Attachments.Add(Cards.GetHeroCard1().ToAttachment());
break;
case "Online Purchase":
return await stepContext.BeginDialogAsync(nameof(PurchaseFlow), null, cancellationToken);
case "Customer Grivance":
reply.Attachments.Add(Cards.GetHeroCard3().ToAttachment());
break;
case "Order Status":
reply.Attachments.Add(Cards.GetHeroCard6().ToAttachment());
break;
default:
reply.AttachmentLayout = AttachmentLayoutTypes.Carousel;
reply.Attachments.Add(Cards.CreateAdaptiveCardAttachment3());
reply.AttachmentLayout = AttachmentLayoutTypes.Carousel;
reply.Attachments.Add(Cards.GetHeroCard1().ToAttachment());
break;
}
if (user_choice == "Register Product" || user_choice == "Online Purchase" || user_choice == "Customer Grivance")
{
await stepContext.Context.SendActivityAsync(reply, cancellationToken);
Random r = new Random();
var validationcard = Cards.CreateAdaptiveCardAttachment2(_cards[r.Next(_cards.Length)]);
//var feedbackcard = Cards.CustomerFeedback();
await stepContext.Context.SendActivityAsync(MessageFactory.Attachment(validationcard), cancellationToken);
//await stepContext.Context.SendActivityAsync(MessageFactory.Attachment(feedbackcard), cancellationToken);
var accessor = _userState.CreateProperty<UserInput>(nameof(UserInput));
await accessor.SetAsync(stepContext.Context, userinfo, cancellationToken);
return await stepContext.EndDialogAsync(null, cancellationToken);
}
else
{
var options2 = new PromptOptions() { Prompt = reply, RetryPrompt = MessageFactory.Text("Retry") };
return await stepContext.PromptAsync($"{nameof(MainDialog)}.callDialog", options2, cancellationToken);
}
}
private async Task<DialogTurnResult> CallingDialogsAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
{
// First, we use the dispatch model to determine which cognitive service (LUIS or QnA) to use.
var recognizerResult = await _botServices.Dispatch.RecognizeAsync(stepContext.Context, cancellationToken);
// Top intent tell us which cognitive service to use.
var topIntent = recognizerResult.GetTopScoringIntent();
switch (topIntent.intent)
{
case "Mainissue":
return await stepContext.BeginDialogAsync($"{nameof(MainDialog)}.fromMain", stepContext.Values[UserInfo], cancellationToken);
case "ConfirmIntent":
return await stepContext.BeginDialogAsync(nameof(Confirm), null, cancellationToken);
case "EndBotIntent":
return await stepContext.CancelAllDialogsAsync(true, null, null, cancellationToken);
case "InverterData":
await ProcessSampleQnAAsync(stepContext, cancellationToken);
break;
default:
await stepContext.Context.SendActivityAsync(MessageFactory.Text($"I'm sorry I don't know what you mean."), cancellationToken);
break;
}
return await stepContext.EndDialogAsync(null, cancellationToken);
}
private IList<Choice> GetChoices()
{
var cardOptions = new List<Choice>()
{
new Choice() { Value = "Product issue", Synonyms = new List<string>() { "adaptive" } },
new Choice() { Value = "Register Product", Synonyms = new List<string>() { "hero" } },
new Choice() { Value = "Online Purchase", Synonyms = new List<string>() { "hero" } },
new Choice() { Value = "Customer Grivance", Synonyms = new List<string>() { "hero" } },
new Choice() { Value = "Order Status", Synonyms = new List<string>() { "hero" } }
};
return cardOptions;
}
private Task<bool> ValidationAsync(PromptValidatorContext<string> promptContext, CancellationToken cancellationToken)
{
string value = (string)promptContext.Context.Activity.Text;
if (Regex.IsMatch(value, "^[0-9]{10}$"))
{
return Task.FromResult(true);
}
else
{
return Task.FromResult(false);
}
}
private async Task ProcessSampleQnAAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
{
_logger.LogInformation("ProcessSampleQnAAsync");
var results = await _botServices.SampleQnA.GetAnswersAsync(stepContext.Context);
if (results.Any())
{
await stepContext.Context.SendActivityAsync(MessageFactory.Text(results.First().Answer), cancellationToken);
}
else
{
await stepContext.Context.SendActivityAsync(MessageFactory.Text("Sorry, could not find an answer in the Q and A system."), cancellationToken);
}
}
}
答案 5 :(得分：0)
就我而言，当我运行多线程任务并遵循解决方案表格EL Vany时，会收到此消息。他的解决方案非常好。现在，我可以毫无例外地同时运行100个线程。