在MVC中为什么我不能为控制器的会话添加值？ [英] In MVC why I cannot add a value to a session of a controller?

问题描述

在此代码中：

In this code:

CardexController controller = new CardexController();
controller.Session.Add("cmstr", id);
controller.Index();

我在行上遇到 System.NullReferenceException 错误：

controller.Session.Add("cmstr", id);

当id有价值而且它不是空的时候我该怎么办？



我是什么尝试过：



会话听起来像一个界面，所以我无法创建它的新实例。而且我也无法为它添加值。

What should I do while id has value and it is not empty?

What I have tried:

Session sounds like an interface so I cannot make a new instance of it. And also I cannot add a value to it.

推荐答案

会话你的财产 CardexController 实例是空的，毫无疑问。

现在是时候在初始化控制器的行上设置一个断点，然后按F5。



Session属性需要一个实现给定接口的对象的实例（我只是从你写的内容中推断，因为我没有类的正式定义），这并不意味着你不必为它提供有效的实例。

Session property of you CardexController instance is null, undoubtably.
It's time for you to put a breakpoint on the line which initializes the controller, and press F5.

The fact that the Session property expects some instance of an object which implements a given interface (I just extrapolate from what you wrote, as I do not have the formal definition of the class), does not mean that you do not have to provide it with a valid instance.

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