autofac with asp.net webforms Instances cannot be resolved and nested lifetimes cannot be

问题

I get following exception "Instances cannot be resolved and nested lifetimes cannot be created from this LifetimeScope as it has already been disposed." when i try to resolve object from global.asax Application_EndRequest event. I use Autofac in version 2.5.2.830

public class Global : System.Web.HttpApplication, IContainerProviderAccessor
{
    // Provider that holds the application container.
    static Autofac.Integration.Web.IContainerProvider _containerProvider;

    // Instance property that will be used by Autofac HttpModules
    // to resolve and inject dependencies.
    public Autofac.Integration.Web.IContainerProvider ContainerProvider
    {
        get { return _containerProvider; }
    }
    protected void Application_Start(object sender, EventArgs e)
    {
        var builder = new ContainerBuilder();
...
        _containerProvider = new ContainerProvider(builder.Build());
    }

    protected void Application_BeginRequest(object sender, EventArgs e)
    {
        ISession session = _containerProvider.RequestLifetime.Resolve<ISession>();
        session.BeginTransaction();
    }

    private void Application_EndRequest(object sender, EventArgs e)
    {
        ISession session = ContainerProvider.RequestLifetime.Resolve<ISession>();
    }

I register in that way:

builder.Register(x => x.Resolve().OpenSession()).As().InstancePerHttpRequest(); }

回答1:

Autofac does its session disposal through an HttpModule called Autofac.Integration.Web.ContainerDisposalModule.

You need to either

Put your own session cleanup in a module that is run before the container disposal. This can be a problem as the order of HttpModules is not guaranteed.

Remove the Container disposal HttpModule from the web.config and do your own lifetime scope cleanup in your Application EndRequest

private void Application_EndRequest(object sender, EventArgs e)
{
    ISession session = ContainerProvider.RequestLifetime.Resolve();
    //cleanup transaction etc...
    ContainerProvider.EndRequestLifetime();     
}

Create a session manager class that is IDisposable and lifetime scoped, take your ISession as a constructor dependency and do your session cleanup when it is Disposed at the end of the lifetime.


    public class SessionManager : IDisposable
    {
        private readonly ISession _session;
        private ITransaction _transaction;

        public SessionManager(ISession session)
        {
            _session = session;
        }

        public void BeginRequest()
        {
            _transaction = _session.BeginTransaction();
        }

        #region Implementation of IDisposable

        /// 
        /// Dispose will be called automatically by autofac when the lifetime ends
        /// 
        public void Dispose()
        {
            //commit rollback, whatever
            _transaction.Commit();
        }

        #endregion
    }

You must make sure to initialize your session manager.


    protected void Application_BeginRequest(object sender, EventArgs e)
    {
        SessionManager manager = _containerProvider.RequestLifetime.Resolve();
        manager.BeginRequest();
    }

来源：https://stackoverflow.com/questions/9340828/autofac-with-asp-net-webforms-instances-cannot-be-resolved-and-nested-lifetimes

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