注入的 HttpContext 始终为空
本文关键字:HttpContext 注入 | 更新日期: 2023-09-27 18:34:25
老实说,这令人兴奋,我无法让它工作。上下文始终为空,无论它被注入何处...
我是否必须在 Startup.cs 中添加上下文的实例?如果是,如何?
发起呼叫
services.AddTransient<SessionService>();
Toast.Configure(app.ApplicationServices.GetRequiredService<SessionService>());
_session.Set("foo", "bar");
吐司课
public class Toast
{
private static SessionService _session;
public static void Configure(SessionService sessionService)
{
_session = sessionService;
Messages = new List<ToastMessage>();
}
}
会话服务
public class SessionService
{
private readonly IHttpContextAccessor _accessor;
public SessionService(IHttpContextAccessor httpContextAccessor)
{
_accessor = httpContextAccessor;
}
public void Set(string key, string value)
{
_accessor.HttpContext.Session.SetString(key, value);
}
}
异常
System.NullReferenceException
Object reference not set to an instance of an object.
System.Reflection.TargetInvocationException
Exception has been thrown by the target of an invocation.
堆栈跟踪
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object reference not set to an instance of an object.
at EveOps.Services.SessionService.Set(String key, Byte[] value) in C:'Users'youri'Documents'Visual Studio 2015'Projects'EveOps'src'EveOps'Services'SessionService.cs:line 25
at EveOps.Toast.set_Messages(List`1 value) in C:'Users'youri'Documents'Visual Studio 2015'Projects'EveOps'src'EveOps'Toast'Toast.cs:line 41
at EveOps.Toast.Configure(SessionService sessionService) in C:'Users'youri'Documents'Visual Studio 2015'Projects'EveOps'src'EveOps'Toast'Toast.cs:line 18
at EveOps.Startup.Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory) in C:'Users'youri'Documents'Visual Studio 2015'Projects'EveOps'src'EveOps'Startup.cs:line 162
--- End of inner exception stack trace ---
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
at Microsoft.AspNet.Hosting.Startup.ConfigureBuilder.Invoke(Object instance, IApplicationBuilder builder)
at Microsoft.AspNet.Hosting.Startup.ConfigureBuilder.<>c__DisplayClass4_0.b__0(IApplicationBuilder builder)
at Microsoft.AspNet.Hosting.Internal.AutoRequestServicesStartupFilter.<>c__DisplayClass0_0.b__0(IApplicationBuilder builder)
at Microsoft.AspNet.Hosting.Internal.HostingEngine.BuildApplication()
感谢@aguafrommars陈述显而易见的事实; 上下文仅对请求有效,即使我知道这一点,我对 DI 和服务的理解还没有达到很好的水平。
我的问题(伪)的解决方案:
App.Use() {
Toast.Configure(app.ApplicationServices.GetRequiredService<SessionService>());
}