从控制器访问时，我MvcApplication的属性为null [英] Property of my MvcApplication is null when accessing it from a controller

问题描述

我是比较新的ASP.NET MVC所以我有这个一个小麻烦。当应用程序启动，我设置一个属性，以一定的价值。然而，当我尝试在一个控制器来访问该属性（使用<一个href=\"http://stackoverflow.com/questions/1066350/how-to-get-mvcapplication-instance-in-asp-net-controller\">this),该属性始终为空。

有什么事情我误解？

在这里，code的简化版本：

 公共类MvcApplication：System.Web.HttpApplication
{
    内部ExtensionManager扩展{搞定;私人集; }    保护无效的Application_Start（）
    {
        this.Extensions =新ExtensionManager（）;
    }
}公众的ActionResult ListExtension（）
{
    VAR应用= HttpContext.ApplicationInstance为MvcApplication;
    返回查看（app.Extensions.InstalledExtensions）;
}
 

解决方案

有多个的HttpApplication 整个应用生命周期，但的Application_Start 只调用应用程序第一次初始化时一次。

有关更多信息，请参阅本：<一href=\"http://msdn.microsoft.com/en-us/library/ms178473%28VS.80%29.aspx\">http://msdn.microsoft.com/en-us/library/ms178473%28VS.80%29.aspx

我不知道你是想在这里存储（扩展？）什么，但如果全球所有的用户，那么你可以使用一个静态属性，否则它保存在别处。

I'm relatively new to ASP.NET MVC so I'm having a little trouble with this one. When the application start, I set a property to a certain value. Yet when I try to access this property in a controller (using this), the property is always null.

Is it something I am misunderstanding?

Here a simplified version of the code :

public class MvcApplication : System.Web.HttpApplication
{
    internal ExtensionManager Extensions { get; private set; }

    protected void Application_Start()
    {
        this.Extensions = new ExtensionManager();
    }
}

public ActionResult ListExtension()
{
    var app = HttpContext.ApplicationInstance as MvcApplication;
    return View(app.Extensions.InstalledExtensions);
}

解决方案

There are multiple HttpApplication instances created throughout the application lifecycle but Application_Start is only called once when the application first initialises.

See this for more info: http://msdn.microsoft.com/en-us/library/ms178473%28VS.80%29.aspx

I don't know what you are trying to store here (extensions?) but if its global to all users then you could use a static property, otherwise store it somewhere else.

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