從ASP.NET Core中的ExceptionFilterAttribute訪問Controller

Question

使用 ASP.Net Core 2，您如何訪問應用了 ExceptionFilterAttribute 的 Controller 實例？

現在在 Core 中是否有更好的方法來實現共享的“基礎”controller 屬性和方法等？ 比如像Startup那樣放到更高的層級？

在 Core 之前，在 MVC 4 中，我會做這樣的事情：

/// <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>類的Items屬性，用於在請求范圍內共享數據。 這正是您覆蓋案件所需要的。 這是一個示例實現：

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，請在此處查看我的回答。 我提供了一個示例，說明如何結合使用 Microsoft.AspNetCore.Mvc.Filters.IActionFilter 和 Microsoft.AspNetCore.Mvc.Filters.IExceptionFilter 來訪問 controller。