Question

我们在使用Autofac进行范围界定时遇到了一个基本问题。在我们的场景中，我们有一些单例作用域的存储库。这些存储库注入了一个IDbContextProvider（也是单例作用域）。 IDbContextProvider只是注入的Autofac IComponentContext的包装器。当需要DbContext时，存储库会从DBContextProvider请求它。 DbContext的范围是＆＃34; lifetimescope＆＃34;，基本上是每个请求，因为这是一个Web Api。

因此，我们的想法是存储库可以是单例作用域，因为它们中的许多存储区和DBContext的范围由Autofac管理为＆＃34;每个请求＆＃34;。这依赖于Autofac ComponentContext应该理解＆＃34; leaf＆＃34;它当前所在的上下文并返回正确的DbContext。一位同事告诉我这个策略，这是StructurMap表现出来的行为（显然是另一种产品）。对我而言，Autofac将解决当前的叶子问题是有道理的。上下文并返回正确的DbContext，但我们看到DbContext的并发问题，这使我得出结论IComponentContext被固定到拥有它的单例，因此返回相同的DbContext实例。

//This is singleton scoped
public class DbContextProvider : IDbContextProvider
{

    private readonly IComponentContext _componentContext;

    public DbContextProvider(IComponentContext componentContext)
    {
        _componentContext = componentContext;
    }

    public TDbContext GetDbContext<TDbContext>() where TDbContext : IDbContext
    {
        //DbContext is scoped PerLifetimeScope but the component context
        //appears to only understand the context of the singleton that owns 
        //it and returns the same instance no matter the overall context
        //under which is is requested.
        return _componentContext.Resolve<TDbContext>();
    }

}

有没有办法完成我们在这里所要做的事情，或者是将整个依赖关系树作为PerLifetimeScope来确定正确行为的唯一行动方案。

...谢谢

Answer 1

IComponentContext resolve with related lifetime but related lifetime is singleton here, so it will be resolved in container. You should use DependencyResolver.Current.GetService

public class DbContextProvider : IDbContextProvider
{


    public DbContextProvider()
    {

    }

    public TDbContext GetDbContext<TDbContext>() where TDbContext : IDbContext
    {
        //DbContext is scoped PerLifetimeScope but the component context
        //appears to only understand the context of the singleton that owns 
        //it and returns the same instance no matter the overall context
        //under which is is requested.
        return DependencyResolver.Current.GetService.Resolve<TDbContext>();
    }

}

You can check this article also.

Singleton Scoped对象从ComponentContext解析时的Autofac Scoping

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