c#-WPF使用类和子类绑定到DataContext

系统管理员 2024-04-07 13:33 58阅读 0赞

c\#-WPF使用类和子类绑定到DataContext  
2019-11-02 14:05:16 阅读：231 来源： 互联网  
标签：data-binding wpf xaml c

我在wpf中玩数据绑定,遇到问题.这是我的代码：

MainWindow.xaml

MainWindow.xaml.cs

public partial class MainWindow : Window  
\{  
public MainWindow()  
\{  
InitializeComponent();  
MyClass myClass = new MyClass();  
myClass.A = new MySubClass();  
myClass.B = new MySubClass();  
stackpanel.DataContext = myClass;  
\}  
\}  
MyClass.cs

class MyClass : INotifyPropertyChanged  
\{  
private MySubClass a;  
public MySubClass A  
\{  
get \{ return a; \}  
set  
\{  
a = value;  
OnPropertyChanged(“A”);  
OnPropertyChanged(“C”);  
\}  
\}

private MySubClass b;
    public MySubClass B 
    {
        get { return b; }
        set
        {
            b = value;
            OnPropertyChanged("B");
            OnPropertyChanged("C");
        }
    }
    
    public int C
    {
        get { return A.Number + B.Number; }
    }
    
    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged(string p)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(p));
        }
    }

\}  
MySubClass.cs

class MySubClass : INotifyPropertyChanged  
\{  
private int number;  
public int Number  
\{  
get \{ return number; \}  
set  
\{  
number = value;  
OnPropertyChanged(“Number”);  
\}  
\}

public MySubClass()
    {
        Number = 1;
    }
    
    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged(string p)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(p));
        }
    }

\}  
现在,问题是在我运行应用程序后,绑定工作正常.另外,当我在文本框中更改值A.Number和B.Number时,它们也可以更新.但是,只有在应用启动时才更新MyClass.C中的变量C,之后才更新.我需要更改什么,以便当我更改A.Number或B.Number时C更新.谢谢.

解决方法:

在更新数据模型时,是否直接在MySubClass实例上更改Number或将新的子类分配给MyClass实例？即：

myClass.A.Number = 5; // will trigger OnPropertyChanged on MySubClass, but not on MyClass  
不会触发A上的OnPropertyChanged(但当然会更新A.Number).  
为此,您必须执行以下操作：

MySubClass v = new MySubClass()  
v.Number = 5;  
myClass.A = v; // will trigger OnPropertyChanged on MyClass  
更新的答案.您可以执行此操作以捕获a和b中的任何属性更改.

public MyClass()  
\{  
a.PropertyChanged += new PropertyChangedEventHandler(UpdateC);  
b.PropertyChanged += new PropertyChangedEventHandler(UpdateC);  
\}

void UpdateC(object sender, PropertyChangedEventArgs e)  
\{  
OnPropertyChanged(“C”);  
\}

标签：data-binding,wpf,xaml,c  
来源： https://codeday.me/bug/20191102/1991948.html

![在这里插入图片描述][3f0d00a73c834e4b81fdaf0e22cb248b.png]  
![在这里插入图片描述][d9457e2f415a4bb08b65e861b1009764.png]  
![在这里插入图片描述][f1248582997c4ceab0219f7eaa7e238b.png]  
![在这里插入图片描述][0842cc8d23454d4596cf4c44d998e982.png]

[3f0d00a73c834e4b81fdaf0e22cb248b.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/01a746bb0fc44dcba0e6e8b8be9bada3.png
[d9457e2f415a4bb08b65e861b1009764.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/0b74b8e5b4684b59a119ccde58bb91c0.png
[f1248582997c4ceab0219f7eaa7e238b.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/49839425ce3142b69283e84f5ac44b12.png
[0842cc8d23454d4596cf4c44d998e982.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/3ed40c558c9d434a92608425de8d3349.png