在IIS上托管时拆分字符串会引发InvalidOperationException

Question

我写了以下代码：

private string makeMailContents(Klant klant, Mail mail)
{
    var builder = new BodyBuilder();
    var path = Path.Combine("wwwroot/trackers/track_open.png");
    var img = builder.LinkedResources.Add(path);
    byte[] data = Convert.FromBase64String(mail.Content);
    string decoded = Encoding.UTF8.GetString(data);
    string code;
    string final = "";
    Regex regex = new Regex(@"\[([^]]*)\]");

    img.ContentId = MimeUtils.GenerateMessageId();

    var splitContent = decoded.Split(' ');

    foreach(string word in splitContent) // this is line 265
    { 
            if (word.Contains('[') && word.Contains(']'))
            {
                try
                {
                    code = Regex.Match(word, @"\[([^]]*)\]").Groups[1].Value.ToLower();
                    switch (code)
                    {
                        case "voornaam":
                            final += regex.Replace(word, klant.vnaam) + ' ';
                            break;
                        case "achternaam":
                            final += regex.Replace(word, klant.anaam) + ' ';
                            break;
                        case "naam":
                            final += regex.Replace(word, klant.vnaam + ' ' + klant.anaam + ' ');
                            break;
                        case "onderwerp":
                            final += regex.Replace(word, mail.Onderwerp + ' ');
                            break;
                        case "datum":
                            final += regex.Replace(word, DateTime.Now.ToString("dd-MM-yyyy") + ' ');
                            break;
                    }
                }
                catch (Exception ex)
                {
                    final += ex;
                }
            }
            else
            {
                final += word + ' ';
            }
    }
}

每当我在本地计算机和测试服务器上运行此代码时，它便会像应该执行的代码一样毫无例外地执行代码。

但是，每当我在当前的实时服务器上托管它时，它都会引发以下异常：

InvalidOperationException：序列不包含任何元素

而且这个异常一直指向splitContent ，它告诉我它不包含元素。 是的， mail.Content填充了有效的base64字符串，我同时检查了提琴手和邮递员。

有人对这里发生的事情有丝毫线索吗？ 我也不确定是IIS设置还是我的代码。 我通常有一个管理IIS的同事，但他现在正在休假。 有人可以帮我这个忙吗？

这是邮件在调用时收到的数据：

 {      
    "Onderwerp":"Dit is een test campagne",
    "afzender":1,
    "campagne":1,
    "Content":"PHA+RGl0IGlzIGVlbiB0ZXN0IG1hYXQ8L3A+Cg==",
    "docs":"['kamer2.jpg']",
    "template":null,
    "verzenddat":"8/17/18, 3:55 PM"
}

完全例外：

System.InvalidOperationException: Sequence contains no elements
   at System.Linq.Enumerable.Last[TSource](IEnumerable`1 source)
   at lambda_method(Closure , QueryContext )
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass17_1`1.<CompileQueryCore>b__0(QueryContext qc)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)
   at System.Linq.Queryable.Last[TSource](IQueryable`1 source)
   at MailerAPI.Mailer.Sender.makeMailContents(Klant klant, Mail mail) in C:\Users\Hofkey\Source\Repos\MailerAPI\MailerAPI\Mailer\Sender.cs:line 265
   at System.Dynamic.UpdateDelegates.UpdateAndExecute3[T0,T1,T2,TRet](CallSite site, T0 arg0, T1 arg1, T2 arg2)
   at MailerAPI.Mailer.Sender.<sendMessage>d__7.MoveNext() in C:\Users\Hofkey\Source\Repos\MailerAPI\MailerAPI\Mailer\Sender.cs:line 161
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MailerAPI.Controllers.MailController.<Post>d__13.MoveNext() in C:\Users\Hofkey\Source\Repos\MailerAPI\MailerAPI\Controllers\MailController.cs:line 96
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeActionMethodAsync>d__12.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeNextActionFilterAsync>d__10.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeInnerFilterAsync>d__14.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.<InvokeNextResourceFilter>d__22.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.<InvokeFilterPipelineAsync>d__17.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.<InvokeAsync>d__15.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.<Invoke>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Cors.Infrastructure.CorsMiddleware.<Invoke>d__7.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.<Invoke>d__7.MoveNext()

当我仅用纯字符串替换模型属性时，也会引发异常。

更新每当我在值控制器中运行此代码以测试decoded.split(' ')它实际上都可以工作。 当我返回decoded.split(' ')我实际上得到了一个字符串数组。

因此，现在我知道问题仅出现在方法中，该方法位于Sender类中，并在MailerController中被调用，并且也仅在当前服务器中发生。

Answer 1

您似乎正在通过或通过位于C:\\Users\\Hofkey\\Source\\Repos\\MailerAPI\\MailerAPI\\Mailer\\Sender.cs:line 265处的代码来调用.Last() 。

Linq扩展方法.Last()要求至少可以抓取一项。 要变通解决此要求，您有多种选择：

• 使用.LastOrDefault()以及适当的null处理，或者
• 在使用.Last()之前，首先检查if (... .Any())是否可以调用.Last() 。

有关更多参考，请参见LINQ元素操作。