asp.net mvc的不能在基本控制器访问Cookie数据 [英] asp.net mvc can't access cookie data in base controller

问题描述

有关要求的每一页，我需要检查一个cookie或创建它，如果它不存在。
如果cookie是存在的，我需要加载从DB一些信息基于cookie的内容。

For every page requested, I need to check a cookie or create it if it's not there. If the cookie is there, I need to load up some info from the DB based on the contents of that cookie.

要做到这一点我创建了一个叫做AppController的，我的其他控制器继承基控制器。

To do this I have created a base controller called AppController that my other controllers inherit from.

然后我有这样的事（这样CurrentSessionValues​​对象是提供给我的所有控制器）：

then I have something like this (so that the CurrentSessionValues object is available to all my controllers):

    public MySession CurrentSessionValues;
    public ApplicationController()
    {
        if (Request.Cookies["MySiteCookie"] == null)
        {
            // create new Record in DB
            CurrentSessionValues = CreateMySession();
            HttpCookie cookie = new HttpCookie("MySiteCookie");
            cookie.Value = CurrentSessionValues.SessionID.ToString;
            Response.SetCookie(cookie);
        }
        else
        {
           // use the value in MySiteCookie to get values from the DB
           // e.g. logged in user id, cart id, etc
        }

    }

当我运行它，我得到Default.aspx中这个错误：

When I run this, I get this error in default.aspx:

在创建时出现错误
  型控制器
  Mvc_Learn.Controllers.HomeController。

An error occurred while creating a controller of type 'Mvc_Learn.Controllers.HomeController'.

如果控制器不具有
  控制器工厂，保证其具有
  无参数的公共构造函数。

If the controller doesn't have a controller factory, ensure that it has a parameterless public constructor.

它打破了对Request.Cookies时[MySiteCookie]

It breaks on Request.Cookies["MySiteCookie"]

我应该以某种方式或其他地方做这个逻辑？

Should I be doing this logic in some other way or another place?

推荐答案

技巧是，你不必在构造背景下必然。相反，你应该重写初始化方法：

Trick is that you don't have context in the constructor necessarily. Rather, you should override the Initialize method:

protected override void Initialize(System.Web.Routing.RequestContext requestContext)
{
    //check request context for cookie and do your thang.
}

PS：为子孙后代，我要指出为什么会出现错误。异常信息的关键部分是发生了一个错误，同时创造控制器，参数构造位在这种情况下，一个红色的鲱鱼。而发生的错误是一个空引用例外HttpContext的。

PS: for posterity, I should note why there is an error. The key part of the exception info is that an error took place while creating the controller, the parameterless constructor bit is a red herring in this case. The error which took place was a null reference exception to HttpContext.

这篇关于asp.net mvc的不能在基本控制器访问Cookie数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！