更新字段时，属性更改 [英] Update field when property changes

问题描述

这可能是一个基本的问题，因为我是新来WPF ..

我有一个包含一个文本框和一个按钮（代码简化了用户控件这个问题）：

 <用户控件X：名称=这种> 
<文本框的文本={绑定的ElementName =此，路径= MyProperty.Value}/> 
<按钮X：NAME =用作MyButton点击=Button_Click/> 
< /用户控件> 
  

在后面的代码我已经注册myProperty的为DependencyProperty的：

 公共静态只读的DependencyProperty MyPropertyProperty = DependencyProperty.Register（myProperty的的typeof（myProperty的）的typeof（MyPropertyNumeric），新UIPropertyMetadata（NULL））; 
  

一个myProperty的是我定义的类，即实现INotifyPropertyChanged。 MyProperty.Value是对象类型。

在单击该按钮，我更改代码隐藏MyProperty.Value。我想有文本框自动显示新值。我希望的是，以上会的工作，因为我已经实现INotifyPropertyChanged的 - 但事实并非如此..任何人都知道如何做到这一点。

解决方案

你叫你的财产，当它被更新的名称OnPropertyChanged事件？

例如，

 公共类myProperty的：INotifyPropertyChanged的{
私人字符串_value; 
 
公共字符串值{{返回_value; }集合{_value =值; OnPropertyChanged（值）; }} 
 
公共事件PropertyChangedEventHandler的PropertyChanged; 
 
保护无效OnPropertyChanged（字符串名称）{
 PropertyChangedEventHandler处理器=的PropertyChanged; 
如果（处理！= NULL）{
处理器（这一点，新PropertyChangedEventArgs（名））; 
} 
} 
} 
  

，以确保它是非常重要的PropertyChanged事件被激发与您要更新的属性的名称。

This is probably a basic question, since I'm new to WPF..

I have a UserControl that contains a TextBox and a Button (code is simplified for this question) :

<UserControl x:Name="this">
    <TextBox Text="{Binding ElementName=this, Path=MyProperty.Value}"/>
    <Button x:Name="MyButton" Click="Button_Click"/>
</UserControl>

In the code behind I have registered "MyProperty" as DependencyProperty:

public static readonly DependencyProperty MyPropertyProperty = DependencyProperty.Register("MyProperty", typeof(MyProperty), typeof(MyPropertyNumeric), new UIPropertyMetadata(null));

A "MyProperty" is a class defined by me, that implements INotifyPropertyChanged. "MyProperty.Value" is of type object.

When the button is clicked, I change MyProperty.Value in the code-behind. I want to have the TextBox to automatically show the new value. I would expect that the above would work, since I've implemented INotifyPropertyChanged - but it doesn't.. Anyone knows how to do this?

解决方案

Are you calling the OnPropertyChanged event with the name of your property when it is updated?

Eg,

public class MyProperty : INotifyPropertyChanged {
  private string _value;

  public string Value { get { return _value; } set { _value = value; OnPropertyChanged("Value"); } }

  public event PropertyChangedEventHandler PropertyChanged;

  protected void OnPropertyChanged(string name) {
    PropertyChangedEventHandler handler = PropertyChanged;
    if(handler != null) {
      handler(this, new PropertyChangedEventArgs(name));
    }
  }
}

It is important to make sure the PropertyChanged event is fired with the name of the property you want to update.

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