我正在尝试在IAuthorizationFilter的实现中使用我的UnitOfWork,但是在我在几个页面之间导航后,我得到了这个异常:
System.InvalidOperationException: The operation cannot be completed because the DbContext has been disposed.
FilterConfig.cs
filters.Add(DependencyResolver.Current.GetService(typeof(PermissionFilter)));
NinjectMappings.cs
public class NinjectMappings : NinjectModule
{
public override void Load()
{
Bind<MyContext>().ToSelf().InRequestScope();
Bind<IUnitOfWork>().To<UnitOfWork>();
}
}
PermissionFilter.cs
public class PermissionFilter : IAuthorizationFilter
{
public PermissionFilter(IUnitOfWork unitOfWork)
{
// etc...
}
}
我能够解决这个问题:
// NinjectMappings
Bind<IUnitOfWork>()
.ToMethod(m => GetUnitOfWork())
.WhenInjectedExactlyInto(typeof(PermissionFilter));
private IUnitOfWork GetUnitOfWork()
{
return new UnitOfWork(new MyContext());
}
现在的问题是GetUnitOfWork只在应用启动时调用一次.我尝试在InTransientScope和InRequestScope之间交替无济于事.因此,不会检索数据库的更新,而是我的UnitOfWork始终返回相同的数据.
我已经阅读了很多处理DbContext的问题,但是他们都没有实现IAuthorizationFilter.
解决这个问题的最佳方法是什么?我想避免使用过滤器中的new或using()或使用Service Locator模式.
最佳答案 您的问题来自于MyContext在请求范围内实例化并在请求结束时处理.
要解决这个问题,避免使用new(),using或ServiceLocator模式,您可以依赖专用的IFilterProvider
public class PermissionFilterProvider : IFilterProvider
{
private readonly Func<PermissionFilter> _permissionFilterFactory = null;
public PermissionFilterProvider(Func<PermissionFilter> filterFactory)
{
_permissionFilterFactory = filterFactory;
}
public IEnumerable<Filter> GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
{
var filters = new List<Filter>();
// instantiate PermissionFilter action filter
filters.Add(new Filter(_permissionFilterFactory(), FilterScope.Action, 0));
return filters;
}
}
您的绑定将是:
public class NinjectMappings : NinjectModule
{
public override void Load()
{
Bind<MyContext>().ToSelf().InRequestScope();
Bind<IUnitOfWork>().To<UnitOfWork>();
Bind<IFilterProvider>().To<PermissionFilterProvider>();
Bind<PermissionFilter>().ToSelf();
}
}
请注意,您将需要像Ninject.Extensions.Factory这样的Ninject Factory扩展来实现Func< PermissionFilter> PermissionFilterProvider构造函数中的工厂模式.
另外,我不确定您的IUnitOfWork的范围.它不应该与你的MyContext相同吗?