C# ASP.NET MVC RestAPI : Process headers before body and and parameters are received

Question

通常在网络协议(protocol)中，会预处理请求头，然后处理请求体。 对于 HTTP，我不确定，但我想知道是否有任何方法可以在请求正文及其参数之前处理 header ？

用 C# 的方式来说，在 Controller 方法被触发之前是否有任何方法可以处理请求 header ？

如果答案是肯定的，我想将客户端版本发送到我的服务器，以防它们不匹配发送客户端合适的响应。我想这样做，因为我的请求正文可能很大(例如 10MB)，并且我想在等待接收整个 HTTP 请求之前预处理 header 。

Answer 1

答案是肯定的，您可以使用操作过滤器。 https://learn.microsoft.com/en-us/aspnet/core/mvc/controllers/filters?view=aspnetcore-3.1#action-filters

public class MySampleActionFilter : IActionFilter
{
    public void OnActionExecuting (ActionExecutingContext context)
    {
        // Do something before the action executes.
    }

    public void OnActionExecuted(ActionExecutedContext context)
    {
        // Do something after the action executes.
    }
}

根据文档，您可以覆盖操作上下文并短路结果，而无需进入 Controller 。

Result - setting Result short-circuits execution of the action method and subsequent action filters.

您可以像这样找到标题

var headers = context.HttpContext.Request.Headers;

// Ensure that all of your properties are present in the current Request
if(!String.IsNullOrEmpty(headers["version"])
{
     // All of those properties are available, handle accordingly

     // You can redirect your user based on the following line of code
     context.Result = new RedirectResult(url);
}
else
{
     // Those properties were not present in the header, redirect somewhere else
}