问题
I'm just starting to use Glimpse with my MVC5 project and have run into an issue when I use Postal to send an email without disabling Glimpse. I've been able to narrow it down to an issue with both packages - it doesn't occur if the Glimpse cookie has not been turned on.
In Fiddler, I checked the difference between the two. When it threw the exception, the cookie was
glimpsePolicy=On
when it worked (Glimpse was off) there were two cookies
glimpseId=FBar; glimpsePolicy=
The exception I get is
System.ArgumentNullException: Value cannot be null.
Parameter name: controllerContext
at System.Web.Mvc.ChildActionValueProviderFactory.GetValueProvider(ControllerContext controllerContext)
at Castle.Proxies.Invocations.ValueProviderFactory_GetValueProvider.InvokeMethodOnTarget()
at Castle.DynamicProxy.AbstractInvocation.Proceed()
at Glimpse.Core.Extensibility.ExecutionTimer.Time(Action action)
at Glimpse.Core.Extensibility.AlternateMethod.NewImplementation(IAlternateMethodContext context)
at Castle.DynamicProxy.AbstractInvocation.Proceed()
at Castle.Proxies.ValueProviderFactoryProxy.GetValueProvider(ControllerContext controllerContext)
at System.Web.Mvc.ValueProviderFactoryCollection.GetValueProvider(ControllerContext controllerContext)
at System.Web.Mvc.ControllerBase.get_ValueProvider()
at Glimpse.Mvc.Message.ActionMessageExtension.AsActionMessage[T](T message, ControllerBase controller)
at Glimpse.Mvc.AlternateType.ViewEngine.FindViews.PostImplementation(IAlternateMethodContext context, TimerResult timerResult)
at Glimpse.Core.Extensibility.AlternateMethod.NewImplementation(IAlternateMethodContext context)
at Castle.DynamicProxy.AbstractInvocation.Proceed()
at Castle.Proxies.IViewEngineProxy.FindView(ControllerContext controllerContext, String viewName, String masterName, Boolean useCache)
at System.Web.Mvc.ViewEngineCollection.<>c__DisplayClass6.<FindView>b__4(IViewEngine e)
at System.Web.Mvc.ViewEngineCollection.Find(Func`2 lookup, Boolean trackSearchedPaths)
at System.Web.Mvc.ViewEngineCollection.Find(Func`2 cacheLocator, Func`2 locator)
at Postal.EmailViewRenderer.Render(Email email, String viewName)
at Postal.EmailService.Send(Email email)
at System.Dynamic.UpdateDelegates.UpdateAndExecuteVoid1[T0](CallSite site, T0 arg0)
at System.Web.Mvc.ActionMethodDispatcher.<>c__DisplayClass1.<WrapVoidAction>b__0(ControllerBase controller, Object[] parameters)
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__36(IAsyncResult asyncResult, ActionInvocation innerInvokeState)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult)
at Castle.Proxies.Invocations.AsyncControllerActionInvoker_EndInvokeActionMethod.InvokeMethodOnTarget()
at Castle.DynamicProxy.AbstractInvocation.Proceed()
at Glimpse.Mvc.AlternateType.AsyncActionInvoker.EndInvokeActionMethod.NewImplementation(IAlternateMethodContext context)
at Castle.DynamicProxy.AbstractInvocation.Proceed()
at Castle.Proxies.AsyncControllerActionInvokerProxy.EndInvokeActionMethod(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3c()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass45.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3e()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass30.<BeginInvokeActionMethodWithFilters>b__2f(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass1e.<>c__DisplayClass28.<BeginInvokeAction>b__19()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass1e.<BeginInvokeAction>b__1b(IAsyncResult asyncResult)
I created a quick action to test it. The controller code is:
public void TestEmailExt()
{
var confirmationToken = "ConfirmationToken";
var Phone1 = "**********";
dynamic email = new Email("RegEmail");
email.To = "**@gmail.com";
email.UserName = "UserName";
email.ConfirmationToken = confirmationToken;
email.Phone = Extensions.Right(Phone1, 4);
if (email.To.Contains("@mydomain"))
email.From = INTERNAL_EMAIL_FROM;
else
email.From = EXTERNAL_EMAIL_FROM;
email.Send();
}
回答1:
The reason this fails is because the Postal library creates its own HttpContext instance while rendering the email view as the decompiled CreateControllerContext method inside Postal's EmailViewRenderer class shows:
private ControllerContext CreateControllerContext()
{
HttpContextWrapper httpContextWrapper = new HttpContextWrapper(new HttpContext(new HttpRequest("", this.UrlRoot(), ""), new HttpResponse(TextWriter.Null)));
RouteData routeData = new RouteData();
routeData.Values["controller"] = (object) this.EmailViewDirectoryName;
return new ControllerContext(new RequestContext((HttpContextBase) httpContextWrapper, routeData), (ControllerBase) new EmailViewRenderer.StubController());
}
This means that the setup that Glimpse does at BeginRequest is completely removed, while the hooks are still in place to intercept MVC related calls.
We've had a similar issue where I gave a similar response to why this is not working.
UPDATE :
I mentioned above that a similar issue had been reported previously, but while I was trying to find a more appropriate solution, it seemed that this case is slightly different in that respect that the other similar issue actually executes a controller with the freshly created context resulting in a NullReferenceException in Glimpse specific code, while here we get a NullReferenceException inside MVC specific code, albeit triggered by Glimpse.
System.ArgumentNullException: Value cannot be null.
Parameter name: controllerContext
at System.Web.Mvc.ChildActionValueProviderFactory.GetValueProvider(ControllerContext controllerContext)
And the exception we get here is because the ControllerContext property on the StubController instance (created inline) is null, which would normally be set when executing the controller (which is not the case here).
So the workaround that I proposed below still applies, but can be avoided if the code of the CreateControllerContext() above is slightly modified:
private ControllerContext CreateControllerContext()
{
HttpContextWrapper httpContextWrapper = new HttpContextWrapper(new HttpContext(new HttpRequest("", this.UrlRoot(), ""), new HttpResponse(TextWriter.Null)));
RouteData routeData = new RouteData();
routeData.Values["controller"] = (object) this.EmailViewDirectoryName;
// MODIFIED
var stubController = new EmailViewRenderer.StubController();
var controllerContext = new ControllerContext(new RequestContext(httpContextWrapper, routeData), stubController);
stubController.ControllerContext = controllerContext;
return controllerContext;
}
I've created an issue for this on the Postal issue tracker
END OF UPDATE
I think the best solution, for now, is to disable Glimpse while calling into Postal and restore normal Glimpse behavior back again afterwards. We might include this one way or the other into the Glimpse Core library in one of the upcoming releases as it seems that disabling Glimpse during a specific part of the request processing logic doesn't seem to be that uncommon, but for now the following snippet might help you (beware it makes use of a Glimpse internal key which is not guaranteed to be there in an upcoming release)
public class GlimpseSuppressionScope : IDisposable
{
private const string GlimpseRequestRuntimePermissionsKey = "__GlimpseRequestRuntimePermissions";
private readonly HttpContext currentHttpContext;
private readonly RuntimePolicy? currentRuntimePolicy;
private bool disposed;
public GlimpseSuppressionScope(HttpContext currentHttpContext)
{
if (currentHttpContext == null)
{
throw new ArgumentNullException("currentHttpContext");
}
this.currentHttpContext = currentHttpContext;
this.currentRuntimePolicy = this.currentHttpContext.Items[GlimpseRequestRuntimePermissionsKey] as RuntimePolicy?;
this.currentHttpContext.Items[GlimpseRequestRuntimePermissionsKey] = RuntimePolicy.Off;
}
~GlimpseSuppressionScope()
{
this.Dispose(false);
}
public void Dispose()
{
this.Dispose(true);
GC.SuppressFinalize(this);
}
private void Dispose(bool disposing)
{
if (!this.disposed)
{
if (disposing)
{
if (this.currentHttpContext != null)
{
this.currentHttpContext.Items.Remove(GlimpseRequestRuntimePermissionsKey);
if (this.currentRuntimePolicy.HasValue)
{
this.currentHttpContext.Items[GlimpseRequestRuntimePermissionsKey] = this.currentRuntimePolicy.Value;
}
}
}
this.disposed = true;
}
}
}
which you can then use in your controller action method as shown below:
public void TestEmailExt()
{
using (new GlimpseSuppressionScope(System.Web.HttpContext.Current))
{
var confirmationToken = "ConfirmationToken";
var Phone1 = "**********";
dynamic email = new Email("RegEmail");
email.To = "**@gmail.com";
email.UserName = "UserName";
email.ConfirmationToken = confirmationToken;
email.Phone = Extensions.Right(Phone1, 4);
if (email.To.Contains("@mydomain"))
email.From = INTERNAL_EMAIL_FROM;
else
email.From = EXTERNAL_EMAIL_FROM;
email.Send();
}
}
来源：https://stackoverflow.com/questions/21054440/exception-thrown-when-using-glimpse-and-postal