如何訪問ActionFilter內的屬性？

這是我的 ActionFilter：

public class LogAttribute : ActionFilterAttribute
{
    public LogAttribute(ILoggerFactory logger)
    {
        Logger = logger.CreateLogger<LogAttribute>();
    }

    public string UserId { get; set; }

    public string Path { get; set; }

    public ILogger Logger { get; }

    public override void OnActionExecuting(ActionExecutingContext context)
    {
        var controller = context.Controller as Controller;
        UserId =  User.FindFirstValue(ClaimTypes.NameIdentifier);
        Path = $"{context.HttpContext.Request.Path.Value}[{context.HttpContext.Request.Method}]";
        Logger.LogDebug($"{Path} started. User(id): {UserId}.");
    }
}

我想在我的控制器的其他地方使用 UserId 和 Path 屬性。有簡潔的方法嗎？

uj5u.com熱心網友回復：

我同意 Serge 的觀點，最好將 BaseController 用于此任務。沒有辦法用屬性清楚地做到這一點。

例如：

public abstract class BaseController<T> : Controller where T : ControllerBase
{
    protected readonly ILogger<T> Logger;

    protected BaseController(ILogger<T> logger)
    {
        Logger = logger;
    }
    protected string UserId { get; set; }
    protected string Path { get; set; }

    [NonAction]
    public override void OnActionExecuting(ActionExecutingContext context)
    {
        UserId = User.FindFirstValue(ClaimTypes.NameIdentifier);
        Path = $"{context.HttpContext.Request.Path.Value}[{context.HttpContext.Request.Method}]";
        Logger.LogDebug($"{Path} started. User(id): {UserId}.");
    }
}

public class HomeController : BaseController<HomeController>
{
    public HomeController(ILogger<HomeController> logger): base(logger)
    {
    }
}

或者只是在您的特定控制器中使用覆寫 OnActionExecuting

    public class HomeController: Controller
    {
        private readonly ILogger<HomeController> _logger;
        private string _userId;
        private string _path;

        public HomeController(ILogger<HomeController> logger)
        {
            _logger = logger;
        }

        [NonAction]
        public override void OnActionExecuting(ActionExecutingContext context)
        {
            _userId = User.FindFirstValue(ClaimTypes.NameIdentifier);
            _path = $"{context.HttpContext.Request.Path.Value} 
            [{context.HttpContext.Request.Method}]";
            _logger.LogDebug($"{Path} started. User(id): {UserId}.");
        }
    }

我將向您展示為此使用屬性的一些缺點。

1.您可以使用HttpContext.Items實作IDictionary<object,object>并且可以訪問請求（生命周期作為范圍）。但是為此您必須使用資源過濾器。

[AttributeUsage(AttributeTargets.Class)]
public class SampleLogAttribute : Attribute, IResourceFilter
    {
        public void OnResourceExecuting(ResourceExecutingContext context)
        {
            context.HttpContext.Items["path"] = $"{context.HttpContext.Request.Path}[{context.HttpContext.Request.Method}]";
            context.HttpContext.Items["userId"] = "SomeUserIdFromResource";
        }

        public void OnResourceExecuted(ResourceExecutedContext context)
        {
        }
    }

然后你可以使用 OnActionExecuting 從你的控制器中獲取它

    private string _path;
    private string _userId;
    public override void OnActionExecuting(ActionExecutingContext context)
    {
        _path = HttpContext.Items["path"] as string;
        _userId = HttpContext.Items["userId"] as string;
    }

不這樣做的主要原因 - 您必須知道您的過濾器將值設定為Items并始終在控制器中創建它們。

2.您可以在屬性中使用反射設定私有值

public override void OnActionExecuting(ActionExecutingContext context)
{
    var controller = context.Controller;
    var path = controller.GetType().GetField("_path", BindingFlags.NonPublic | BindingFlags.Instance);
    path?.SetValue(controller, $"{context.HttpContext.Request.Path}[{context.HttpContext.Request.Method}]");
    var userId = controller.GetType().GetField("_userId", BindingFlags.NonPublic | BindingFlags.Instance);
    userId?.SetValue(controller, "SomeUserId");
}

您必須明白，如果您忘記創建基本變數 - 您將無法訪問它們。

uj5u.com熱心網友回復：

如果我的問題是正確的...我們正在嘗試從當前的 Http Requet 中提取 UserId 和 Path（可能是查詢字串）？

如果是這樣，試試這個

public class LogAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext context)
    {
        var userId = context.HttpContext.User.FindFirst(ClaimTypes.NameIdentifier); // claims type depend on how we configure authentication. But many default fall into this constants.
        var path = context.HttpContext.Request.Path;
        var queryString = context.HttpContext.Request.QueryString;
        //... Do whatever we need
    }
}

uj5u.com熱心網友回復：

您可以創建基本控制器

public class BaseController : Controller
    {
      public BaseController(ILoggerFactory logger)
    {
        Logger = logger.CreateLogger<LogAttribute>();
    }

    protected string UserId { get; set; }

    protected string Path { get; set; }

    protected ILogger Logger { get; }
    
        [NonAction]
        public override void OnActionExecuting(ActionExecutingContext context)
        {
       var controllerActionDescriptor = context.ActionDescriptor as 
         ControllerActionDescriptor;
            var controllerName = controllerActionDescriptor?.ControllerName;
            var actionName = controllerActionDescriptor?.ActionName;
        UserId =  User.FindFirstValue(ClaimTypes.NameIdentifier);
        Path = $"{context.HttpContext.Request.Path.Value}[{context.HttpContext.Request.Method}]";
        Logger.LogDebug($"{Path} started. User(id): {UserId}.");
    }
}

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