从ASP.NET Core中的ExceptionFilterAttribute访问Controller

Question

使用 ASP.Net Core 2，您如何访问应用了 ExceptionFilterAttribute 的 Controller 实例？

现在在 Core 中是否有更好的方法来实现共享的“基础”controller 属性和方法等？ 比如像Startup那样放到更高的层级？

在 Core 之前，在 MVC 4 中，我会做这样的事情：

/// <summary>
/// Base controller, shared by all WebAPI controllers for tracking and shared properties.
/// </summary>
[ApiTracking]
[ApiException]
public class BaseApiController : ApiController
{
    private Common.Models.Tracking _Tracking = null;
    public Common.Models.Tracking Tracking
    {
        get
        {
           if(_Tracking == null)
               _Tracking = new Common.Models.Tracking();
           return _Tracking;
        }
    }
    //... other shared properties...
}

/// <summary>
/// Error handler for webapi calls. Adds tracking to base controller.
/// </summary>
public class ApiExceptionAttribute : ExceptionFilterAttribute
{
    public override void OnException(HttpActionExecutedContext cntxt)
    {
        BaseApiController ctrl = cntxt.ActionContext.ControllerContext.Controller as BaseApiController;
        if (ctrl != null)
            ctrl.Tracking.Exception(cntxt.Exception, true);

        base.OnException(actionExecutedContext);
    }
}

/// <summary>
/// Intercepts all requests to inject tracking detail and call tracking.save.
/// </summary>
public class ApiTrackingAttribute : System.Web.Http.Filters.ActionFilterAttribute
{
    public override void OnActionExecuting(HttpActionContext cntxt)
    {
        //...add info to tracking
    }
    public override void OnActionExecuted(HttpActionExecutedContext cntxt)
    {
        BaseApiController ctrl = cntxt.ActionContext.ControllerContext.Controller as BaseApiController;
        if (ctrl != null)
            ctrl.Tracking.Save();
    }
}

Answer 1

ASP.Net Core中的HttpContext包含IDictionary<object, object>类的Items属性，用于在请求范围内共享数据。 这正是您覆盖案件所需要的。 这是一个示例实现：

public class ApiExceptionAttribute : ExceptionFilterAttribute
{
    public override void OnException(ExceptionContext context)
    {
        var items = context.HttpContext.Items;
        if (items.ContainsKey("Tracking"))
        {
            Tracking tracking = (Tracking)items["Tracking"];
            tracking.Exception(context.Exception, true);
        }

        base.OnException(context);
    }
}

public class ApiTrackingAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext context)
    {
        var tracking = new Tracking();
        //...add info to tracking

        context.HttpContext.Items.Add("Tracking", tracking);
    }

    public override void OnActionExecuted(ActionExecutedContext context)
    {
        var items = context.HttpContext.Items;
        if (items.ContainsKey("Tracking"))
        {
            Tracking tracking = (Tracking) items["Tracking"];
            tracking.Save();
        }
    }
}

Answer 2

如果您使用的是 .NET 6 或更高版本，请在此处查看我的回答。 我提供了一个示例，说明如何结合使用 Microsoft.AspNetCore.Mvc.Filters.IActionFilter 和 Microsoft.AspNetCore.Mvc.Filters.IExceptionFilter 来访问 controller。