如何在OnActionExecuting中设置条件避免无限重定向循环？

要解决无限重定向问题，核心思路是在过滤器中判断当前请求是否已经是目标页面，如果是则直接返回，不再执行重定向逻辑。以下是两种适配你场景的实现方案：

方案1：基于路由参数判断（推荐，适配RedirectToRouteResult） #

如果你的路由配置包含language、controller、action参数（比如本地化路由），可以直接从RouteData中读取当前请求的路由信息，判断是否已到达目标页面：

public void OnActionExecuting(ActionExecutingContext context)
{
    // 提取当前请求的路由参数
    var currentController = context.RouteData.Values["controller"]?.ToString() ?? string.Empty;
    var currentAction = context.RouteData.Values["action"]?.ToString() ?? string.Empty;
    var currentLanguage = context.RouteData.Values["language"]?.ToString() ?? string.Empty;

    // 条件：如果当前已是Home控制器的Index动作，且语言匹配目标值，直接返回
    if (currentController.Equals("Home", StringComparison.OrdinalIgnoreCase) &&
        currentAction.Equals("Index", StringComparison.OrdinalIgnoreCase) &&
        (currentLanguage == "en-us" || currentLanguage == "es-mx"))
    {
        return;
    }

    if (context.HttpContext.Request.Cookies["localization"] != null)
    {
        var isoCode = context.HttpContext.Request.Cookies["localization"];
        string targetController = "Home";
        string targetAction = "Index";

        if (isoCode == "en-us")
        {
            context.Result = new RedirectToRouteResult(
                new RouteValueDictionary(new { 
                    language = "en-us",
                    controller = targetController, 
                    action = targetAction 
                })
            );
        }
        else if (isoCode == "es-mx")
        {
            context.Result = new RedirectToRouteResult(
                new RouteValueDictionary(new { 
                    language = "es-mx",
                    controller = targetController, 
                    action = targetAction 
                })
            );
        }
    }
}

配套路由配置 #

确保你的Startup/Program中配置了支持语言前缀的路由：

app.MapControllerRoute(
    name: "localized",
    pattern: "{language}/{controller=Home}/{action=Index}/{id?}");

方案2：基于请求路径前缀判断（适合无路由参数场景） #

如果你的路由没有绑定language参数，直接通过URL路径前缀判断：

public void OnActionExecuting(ActionExecutingContext context)
{
    var requestPath = context.HttpContext.Request.Path.Value.ToLower();

    // 条件：如果当前请求路径已是目标语言页面，直接返回
    if (requestPath.StartsWith("/en-us/home") || requestPath.StartsWith("/es-mx/casa"))
    {
        return;
    }

    if (context.HttpContext.Request.Cookies["localization"] != null)
    {
        var isoCode = context.HttpContext.Request.Cookies["localization"];
        string targetController = "Home";
        string targetAction = "Index";

        if (isoCode == "en-us")
        {
            context.Result = new RedirectToRouteResult(
                new RouteValueDictionary(new { 
                    controller = targetController, 
                    action = targetAction 
                })
            );
            // 若需手动拼接路径，可改用RedirectResult：
            // context.Result = new RedirectResult("/en-us/home");
        }
        else if (isoCode == "es-mx")
        {
            context.Result = new RedirectToRouteResult(
                new RouteValueDictionary(new { 
                    controller = targetController, 
                    action = targetAction 
                })
            );
            // context.Result = new RedirectResult("/es-mx/casa");
        }
    }
}

核心原理 #

两种方案都是通过提前终止过滤器逻辑，避免对已经到达目标页面的请求再次执行重定向，从根源上切断循环链。

内容的提问来源于stack exchange，提问作者PussInBoots