HttpContext.Current.Session is null when routing requests

问题

Without routing, HttpContext.Current.Session is there so I know that the StateServer is working. When I route my requests, HttpContext.Current.Session is null in the routed page. I am using .NET 3.5 sp1 on IIS 7.0, without the MVC previews. It appears that AcquireRequestState is never fired when using the routes and so the session variable isn\'t instantiated/filled.

When I try to access the Session variables, I get this error:

base {System.Runtime.InteropServices.ExternalException} = {\"Session state can only be used when enableSessionState is set to true, either in a configuration file or in the Page directive. Please also make sure that System.Web.SessionStateModule or a custom session state module is included in the <configuration>.

While debugging, I also get the error that the HttpContext.Current.Session is not accessible in that context.

My web.config looks like this:

<configuration>
  ...
  <system.web>
    <pages enableSessionState=\"true\">
      <controls>
        ...
      </controls>
    </pages>
    ...
  </system.web>
  <sessionState cookieless=\"AutoDetect\" mode=\"StateServer\" timeout=\"22\" />
  ...
</configuration>

Here\'s the IRouteHandler implementation:

public class WebPageRouteHandler : IRouteHandler, IRequiresSessionState
{
    public string m_VirtualPath { get; private set; }
    public bool m_CheckPhysicalUrlAccess { get; set; }

    public WebPageRouteHandler(string virtualPath) : this(virtualPath, false)
    {
    }
    public WebPageRouteHandler(string virtualPath, bool checkPhysicalUrlAccess)
    {
        m_VirtualPath = virtualPath;
        m_CheckPhysicalUrlAccess = checkPhysicalUrlAccess;
    }

    public IHttpHandler GetHttpHandler(RequestContext requestContext)
    {
        if (m_CheckPhysicalUrlAccess
            && !UrlAuthorizationModule.CheckUrlAccessForPrincipal(
                   m_VirtualPath,
                   requestContext.HttpContext.User,
                   requestContext.HttpContext.Request.HttpMethod))
        {
            throw new SecurityException();
        }

        string var = String.Empty;
        foreach (var value in requestContext.RouteData.Values)
        {
            requestContext.HttpContext.Items[value.Key] = value.Value;
        }

        Page page = BuildManager.CreateInstanceFromVirtualPath(
                        m_VirtualPath, 
                        typeof(Page)) as Page;// IHttpHandler;

        if (page != null)
        {
            return page;
        }
        return page;
    }
}

I\'ve also tried to put EnableSessionState=\"True\" on the top of the aspx pages but still, nothing.

Any insights? Should I write another HttpRequestHandler that implements IRequiresSessionState?

Thanks.

回答1:

Got it. Quite stupid, actually. It worked after I removed & added the SessionStateModule like so:

<configuration>
  ...
  <system.webServer>
    ...
    <modules>
      <remove name="Session" />
      <add name="Session" type="System.Web.SessionState.SessionStateModule"/>
      ...
    </modules>
  </system.webServer>
</configuration>

Simply adding it won't work since "Session" should have already been defined in the machine.config.

Now, I wonder if that is the usual thing to do. It surely doesn't seem so since it seems so crude...

回答2:

Just add attribute runAllManagedModulesForAllRequests="true" to system.webServer\modules in web.config.

This attribute is enabled by default in MVC and Dynamic Data projects.

回答3:

runAllManagedModulesForAllRequests=true is actually a real bad solution. This increased the load time of my application by 200%. The better solution is to manually remove and add the session object and to avoid the run all managed modules attribute all together.

回答4:

None of these solutions worked for me. I added the following method into global.asax.cs then Session was not null:

protected void Application_PostAuthorizeRequest()
{
    HttpContext.Current.SetSessionStateBehavior(SessionStateBehavior.Required);
}

回答5:

What @Bogdan Maxim said. Or change to use InProc if you're not using an external sesssion state server.

<sessionState mode="InProc" timeout="20" cookieless="AutoDetect" />

Look here for more info on the SessionState directive.

回答6:

Nice job! I've been having the exact same problem. Adding and removing the Session module worked perfectly for me too. It didn't however bring back by HttpContext.Current.User so I tried your little trick with the FormsAuth module and sure enough, that did it.

<remove name="FormsAuthentication" />
<add name="FormsAuthentication" type="System.Web.Security.FormsAuthenticationModule"/>

回答7:

It seems that you have forgotten to add your state server address in the config file.

 <sessionstate mode="StateServer" timeout="20" server="127.0.0.1" port="42424" />

回答8:

The config section seems sound as it works if when pages are accessed normally. I've tried the other configurations suggested but the problem is still there.

I doubt the problem is in the Session provider since it works without the routing.

回答9:

I think this part of code make changes to the context.

 Page page = BuildManager.CreateInstanceFromVirtualPath(
                        m_VirtualPath, 
                        typeof(Page)) as Page;// IHttpHandler;

Also this part of code is useless:

 if (page != null)
 {
     return page;
 }
 return page;

It will always return the page wither it's null or not.

回答10:

a better solution is

runAllManagedModulesForAllRequest is a clever thing to do respect removing and resinserting session module.

alk.

回答11:

I was missing a reference to System.web.mvc dll in the session adapter, and adding the same fixed the issue.

Hopefully it will help someone else going through same scenario.

来源：https://stackoverflow.com/questions/218057/httpcontext-current-session-is-null-when-routing-requests

标签

ASP.NET

routing

session-variables