一步一步学习MVVM模式二 增删改

添加功能，就是做一个建立一个新的实例，然后这个实例绑定到各个控件上面，点击提交按钮的时候，提交按钮的命令command注册到一个添加的方法.

整个流程就是：

建一个新的实例,添加按钮绑定AddCommond， AddCommand在ViewModel里注册一个添加新实例的方法，

删除一个实例，和添加实例一样首先要绑定DeleteCommand绑定到删除按钮，然后

DeleteCommand在ViewModel里注册一个删除方法，与添加不一样的是：删除需要传递参数，删除实例通过

<Button Content="删除" Height="37" Margin="10,0,8,0" Command="{Binding RemoveCommand}" CommandParameter="{Binding SelectedItem, ElementName=dataGrid}"/>

ViewModel中代码如下：

 1 public class ServerViewModel:INotifyPropertyChanged
 2     {
 3         private ServerModel sm;
 4         private Server currentServer;
 5         public Server CurrentServer
 6         {
 7             get { return currentServer; }
 8             set
 9             {
10                 CurrentServer = value;
11                 this.OnPropertyChanged("CurrentServer");
12             }
13         }
14 
15         private ICommand _addCommond;
16         private ICommand _modifyCommond;
17 
18         public ServerViewModel()
19         { 
20             sm=new ServerModel();
21             currentServer = new Server();
22             serverList = sm.GetServerList();
23         }
24 
25         public ICommand AddCommand
26         {
27             get
28             {
29                 if (_addCommond == null)
30                 {
31                     _addCommond = new ActionCommand(Add);
32                 }
33 
34                 return _addCommond;
35             }
36         }
37 
38         private void Add()
39         {
40             if (serverList != null)
41             {
42                 serverList.Add(currentServer);
43                 currentServer = new Server();
44             }
45         }
46 
47         private ICommand _deleteCommond;
48         public ICommand RemoveCommand
49         {
50             get
51             {
52                 if (_deleteCommond == null) _deleteCommond = new ActionCommand(Delete);
53                 return _deleteCommond;
54             }
55         }
56 
57         private void Delete(object obj)
58         {
59             Server server = obj as Server;
60             if (serverList != null)
61             {
62                 serverList.Remove(server);
63             }
64         }
65 
66         private ObservableCollection<Server> serverList;
67         public ObservableCollection<Server> ServerList 
68         {
69             get { return serverList; }
70             set 
71             { 
72                 serverList = value;
73                 this.OnPropertyChanged("ServerList");
74             }
75         }
76 
77         public event PropertyChangedEventHandler PropertyChanged;
78 
79         private void OnPropertyChanged(string propertyName)
80         {
81             if (PropertyChanged != null)
82                 PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
83         }
84     }

修改就更简单了，由于绑定是双向的，任务更改都会更新，所以直接做双向绑定就可以了，不用单独做。

Demo 暂不能下载，压缩文件上传出错，哪天能上传了再上传。