c# - Difference between datacontext and normal object creation in C#

Question

I have seen a video where at different windows, the presenter follows different styles.

For instance:

In one window, he uses like this below:

EmployeeViewModel evm = (EmployeeViewModel)this.DataContext;
evm.Display();

In another, he uses like:

EmployeeViewModel evm = new EmployeeViewModel();
evm.Display();

Whats the difference technically and the best way to use ? Please help me understand the difference.

Answer 1

第一个代码片段检索当前显示的 ViewModel。（它应该做一个空检查）

第二个代码片段创建一个 ViewModel 的新实例。

因为不清楚 Display() 做了什么，所以很难解释两个片段的效果之间的区别，但可能是第二个片段是忽略视图的 ViewModel 的（单元）测试。

据我所知，没有最好的方法，因为两个片段都有不同的目的。