那些遇到过的问题

kernel.Get <type>的InvalidCastException

Mat*_*don 5 c# wpf ninject

我有一个WPF应用程序,可能会或可能不会启动命令行args.我曾经OnStartup(StartupEventArgs e)在App.xaml代码隐藏的方法中使用了我的组合根,但是这导致应用程序关闭问题所以我将App.xaml变成了"页面"(而不是"应用程序定义")并编写了我自己的Program类包含我自己的应用程序入口点,这将成为我的新组合根位置.

由于这个改变,我一直无法启动应用程序,Ninject似乎无法解析应用程序的主要对象(或者它可能是它的依赖项之一？).

这个异常让我浪费了很多时间,堆栈跟踪都是Ninject-internal,我不知道在我的代码中修复了什么,我绑定现在导致此异常的类型的方式最近没有改变:

at DynamicInjector54d92ac63a2e47fda5ffbcc19b9942a9(Object[] )
at Ninject.Activation.Providers.StandardProvider.Create(IContext context)
at Ninject.Activation.Context.Resolve()
at Ninject.KernelBase.<>c__DisplayClass10.<Resolve>b__c(IBinding binding)
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
at Ninject.Planning.Targets.Target`1.GetValue(Type service, IContext parent)
at Ninject.Planning.Targets.Target`1.ResolveWithin(IContext parent)
at Ninject.Activation.Providers.StandardProvider.GetValue(IContext context, ITarget target)
at Ninject.Activation.Providers.StandardProvider.<>c__DisplayClass4.<Create>b__2(ITarget target)
at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at Ninject.Activation.Providers.StandardProvider.Create(IContext context)
at Ninject.Activation.Context.Resolve()
at Ninject.KernelBase.<>c__DisplayClass10.<Resolve>b__c(IBinding binding)
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
at Ninject.Planning.Targets.Target`1.GetValue(Type service, IContext parent)
at Ninject.Planning.Targets.Target`1.ResolveWithin(IContext parent)
at Ninject.Activation.Providers.StandardProvider.GetValue(IContext context, ITarget target)
at Ninject.Activation.Providers.StandardProvider.<>c__DisplayClass4.<Create>b__2(ITarget target)
at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at Ninject.Activation.Providers.StandardProvider.Create(IContext context)
at Ninject.Activation.Context.Resolve()
at Ninject.KernelBase.<>c__DisplayClass10.<Resolve>b__c(IBinding binding)
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
at Ninject.Planning.Targets.Target`1.GetValue(Type service, IContext parent)
at Ninject.Planning.Targets.Target`1.ResolveWithin(IContext parent)
at Ninject.Activation.Providers.StandardProvider.GetValue(IContext context, ITarget target)
at Ninject.Activation.Providers.StandardProvider.<>c__DisplayClass4.<Create>b__2(ITarget target)
at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at Ninject.Activation.Providers.StandardProvider.Create(IContext context)
at Ninject.Activation.Context.Resolve()
at Ninject.KernelBase.<>c__DisplayClass10.<Resolve>b__c(IBinding binding)
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at System.Linq.Enumerable.<CastIterator>d__b1`1.MoveNext()
at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source)
at Ninject.ResolutionExtensions.Get[T](IResolutionRoot root, IParameter[] parameters)
at MyProgram.Program.Main(String[] args) in C:\Dev\MyProject\MyProject.WinPresentation\Program.cs:ligne 40
at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
Run Code Online (Sandbox Code Playgroud)

这是Main方法/应用程序入口点:

[STAThread]
public static void Main(string[] args)
{
    var module = new MyAppNinjectModule(args);
    var kernel = new StandardKernel(module);

    var argsHelper = module.CommandLineArgs;

    var logProvider = kernel.Get<ILogProvider>();
    var logger = logProvider.GetLogger(typeof(Program).Name);

    if (argsHelper.LoggingDisabledArgument.IsSpecified()) logProvider.DisableLogging();
    logger.Info(log.LogAppStart);

    var installer = kernel.Get<IInstaller>(); // >>> InvalidCastException here

    if (argsHelper.QuietInterfaceArgument.IsSpecified())
    {
        // running with -quiet command-line switch: just execute and exit.
        installer.Execute();
    }
    else
    {
        // instantiate a new App object (WPF), and run it.
        // installer.Execute() may or may not be executed, depending on user actions.
        var app = new App(installer);
        app.Run();
    }
}
Run Code Online (Sandbox Code Playgroud)

NinjectModule IInstaller根据提供的命令行参数绑定到这样或那样的实现(例如,SilentInstaller何时QuietInterfaceArgument指定,ManualInstaller何时不指定等).

通常Ninject会提供非常有用和详细的异常消息 - 当它的ActivationException生命是好的时候.但这InvalidCastException让我一无所知,我不是表演无效演员的人,我甚至不知道涉及哪些类型.我只知道我可能已经编写了一些Ninject不喜欢的代码,这可能与我绑定IInstaller到它的实现的方式有关,但是如果我注释掉NinjectModule的"分支"部分强制绑定ManualInstaller我所追求的特定实现(),它仍然失败了InvalidCastException.

实现的构造函数: 

public ManualInstaller(IView<MainWindowViewModel> view, 
                       IProcessHelper processHelper,
                       ISettingsHelper settingsHelper,
                       ILogProvider logProvider,
                       ISetupBootstrapper installer,
                       bool notifySuccess)
    : base(notifySuccess, processHelper, settingsHelper, logProvider, installer)
Run Code Online (Sandbox Code Playgroud)

相应的绑定代码(其余的依赖项已经绑定,并且ActivationException不确定这与我的问题有多相关):

var msg = string.Empty;
if (CommandLineArgs.CompletionMessageArgument.IsSpecified()) 
    msg = CommandLineArgs.CompletionMessageArgument.ParameterValue();

Bind<MainWindowViewModel>().ToSelf().WithConstructorArgument("completionMessage", msg);
Bind<IView<MainWindowViewModel>>().To<MainWindow>();

Bind<IInstaller>().To<ManualInstaller>()
                  .WithConstructorArgument("notifySuccess", notifySuccess);
Run Code Online (Sandbox Code Playgroud)

如果需要其他任何东西来了解发生了什么,请不要犹豫,让我知道......

编辑

单独解决安装程序的依赖关系会产生更多信息:

// resolve installer dependencies:
var view = kernel.Get<IView<MainWindowViewModel>>(); // >>> InvalidCastException here
var processHelper = kernel.Get<IProcessHelper>();
var settingsHelper = kernel.Get<ISettingsHelper>();
var bootstrapper = kernel.Get<ISetupBootstrapper>();
var installer = new ManualInstaller(view, processHelper, settingsHelper, logProvider, bootstrapper, true);
Run Code Online (Sandbox Code Playgroud)

所以我至少可以将它缩小到我试图解决的类型的一个特定依赖:问题是View或者它的唯一依赖,ViewModel.所以我这样做了:

// resolve ViewModel dependencies:
var processHelper = kernel.Get<IProcessHelper>(); // >>> InvalidCastException here
var settingsHelper = kernel.Get<ISettingsHelper>();
var messenger = kernel.Get<INetworkMessenger>();
var factory = kernel.Get<IBuildServerFactory>();
var dialogs = kernel.Get<ICommonDialogs>();
Run Code Online (Sandbox Code Playgroud)

显然,这是IProcessHelper实现的问题 - 再次:

// resolve ProcessHelper dependencies:
var processWrapper = kernel.Get<IProcessWrapper>();
var wmiWrapper = kernel.Get<IWindowsManagementInstrumentationWrapper>();
var helper = new ProcessHelper(processWrapper, wmiWrapper, logProvider, 300);
Run Code Online (Sandbox Code Playgroud)

现在我不再得到了InvalidCastException.

这是有问题的类'构造函数和字段:

private readonly ILogProvider _logProvider;
private readonly IProcessWrapper _process;
private readonly IWindowsManagementInstrumentationWrapper _wmi;
public int TimeoutSeconds { get; private set; }

public ProcessHelper(IProcessWrapper process, 
                     IWindowsManagementInstrumentationWrapper wmiWrapper, 
                     ILogProvider logProvider, 
                     int timeout)
{
    _logProvider = logProvider;
    _process = process;
    _wmi = wmiWrapper;
    TimeoutSeconds = timeout;
}
Run Code Online (Sandbox Code Playgroud)

以及NinjectModule如何绑定它:

Bind<IProcessHelper>().To<ProcessHelper>()
                      .WithConstructorArgument("timeout", Properties.Settings.Default.ProcessTimeoutSeconds);
Run Code Online (Sandbox Code Playgroud)

**重新编辑**

在@jure的评论的帮助下,我发现ProcessTimeoutSecondsin 的类型Properties.Settings.Default实际上是设置为string- 显然它需要一个int.砰!

jur*_*ure 6

在将常量值传递给WithConstructorArguments设置时,需要确保对象的类型对于实现类构造函数参数有效.

正如您后来发现的那样,您在string对象中将对象作为构造函数参数传递,但构造函数需要这样做int.这给了你InvalidCastException.

作为旁注,如果Ninject给你一些更好的例外会很好,这确实很难调试.

归档时间：

查看次数：

936 次

最近记录：

12 年，4 月 前
相关归档
如何将逗号分隔的字符串转换为List <int> 184
实现C#通用超时 157
为什么我不能使用System.ValueType作为泛型约束？ 48
数字格式:如何将1转换为"01",将2转换为"02"等？ 38
防止窗口焦点变化 15
在视图模型中使用XAML资源 10
使用NoResize模式最小化窗口 10
将WPF样式触发器绑定到自定义依赖项属性 9
XAML名称空间中的"名称空间中不存在"错误 9
WPF TextBlock.TextTrimming不使用自动调整大小的ColumnDefinition 8
难疑归档
如何检查字符串是否包含JavaScript中的子字符串？ 7430
如何在ActionScript 3中将"Null"(真正的姓氏!)传递给SOAP Web服务？ 4603
为什么Java的+ =, - =,*=,/ =复合赋值运算符需要转换？ 3547
电话和申请有什么区别？ 3012
如何测试空的JavaScript对象？ 2730
如何更改一个特定提交的提交作者？ 1949
如何将package.json中的每个依赖项更新为最新版本？ 1871
单击div到底层元素 1500
如何检查对象是否在JavaScript中具有属性？ 1396
Git diff对付藏匿处 1265