在RedirectToAction来电传播查询参数 [英] Propagating QueryString parameter in RedirectToAction calls

问题描述

我要确保在查询字符串特定参数，在我的情况下 REQUEST_ID 传播到重定向动作。

比方说，我有一个行动首先，

  [HttpPost]
公众的ActionResult第一（）
{
    ////////////////////
    // code大量的...
    ////////////////////    返回RedirectToAction（二）;
}
 

现在说了，首先回传了一个参数查询字符串，我想传递给二的行动。做到这一点的一种方法是通过在值 RedirectToAction 调用自身，

 字符串的requestId =的Request.QueryString [REQUEST_ID_KEY]
返回RedirectToAction（二，新的{REQUEST_ID_KEY =的requestId}）;
 

但我必须这样做一系列操作的，我不愿意纳入行动内请求ID传播的逻辑。它会更好，如果我可以纳入这里面的 ActionFilter ，但我不能弄清楚如何参数从ActionFilter添加到查询字符串。任何想法？

解决方案

 公共类preserveQueryStringAttribute：ActionFilterAttribute
{
    公共覆盖无效OnActionExecuted（ActionExecutedContext filterContext）
    {
        VAR redirectResult = filterContext.Result为RedirectToRouteResult;
        如果（redirectResult == NULL）
        {
            返回;
        }        VAR的查询= filterContext.HttpContext.Request.QueryString;
        //注：在这里，你可以决定是否要传播所有
        //查询字符串值或特定的一个。在我的例子，我
        //传播的已经不是一部分的所有查询字符串值
        //路线值
        的foreach（在query.Keys字符串键）
        {
            如果（！redirectResult.RouteValues​​.ContainsKey（键））
            {
                redirectResult.RouteValues​​.Add（键，查询[关键]）;
            }
        }
    }
}
 

和则：

  [HttpPost]
[preserveQueryString]
公众的ActionResult第一（）
{
    ////////////////////
    // code大量的...
    ////////////////////    返回RedirectToAction（二）;
}
 

I want to make sure that a particular parameter in the QueryString, in my case the request_id is propagated to the redirected action.

Say for example, I have an Action First,

[HttpPost]
public ActionResult First() 
{
    ////////////////////
    // Lots of code ...
    ////////////////////

    return RedirectToAction("Second");
}

Now say, the First postback had a parameter in the QueryString, which I would like to pass to the Second action. One way to do it would be to pass the value in the RedirectToAction call itself,

string requestId = Request.QueryString[REQUEST_ID_KEY];
return RedirectToAction("Second", new { REQUEST_ID_KEY = requestId });

But I have to do this in a series of Actions and I am unwilling to incorporate request id propagation logic inside the action. It would be better if I could incorporate this inside an ActionFilter, but I cant figure out how to add parameters to the QueryString from an ActionFilter. Any ideas?

解决方案

public class PreserveQueryStringAttribute : ActionFilterAttribute
{
    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        var redirectResult = filterContext.Result as RedirectToRouteResult;
        if (redirectResult == null)
        {
            return;
        }

        var query = filterContext.HttpContext.Request.QueryString;
        // Remark: here you could decide if you want to propagate all
        // query string values or a particular one. In my example I am
        // propagating all query string values that are not already part of
        // the route values
        foreach (string key in query.Keys)
        {
            if (!redirectResult.RouteValues.ContainsKey(key))
            {
                redirectResult.RouteValues.Add(key, query[key]);
            }
        }
    }
}

and then:

[HttpPost]
[PreserveQueryString]
public ActionResult First() 
{
    ////////////////////
    // Lots of code ...
    ////////////////////

    return RedirectToAction("Second");
}

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