在命令中设置属性时,绑定不会更新 [英] Binding doesn't update when property is set inside a command
问题描述
我有一个令人惊讶的困难,试图使一个简单的事情工作,即设置一个属性在一个方法调用一个命令绑定到一个按钮。
I am having a surprising difficulty trying to make a simple thing work, that is, setting a property in a method called by a Command bound to a Button.
当我在ViewModel构造函数中设置属性时,正确的值在View中正确显示,但是当我使用命令的方法设置此属性时,尽管我创建的任何断点(甚至在 RaisePropertyChanged
在我的 ViewModelBase
中)。我正在使用在线教程(来自乔希·史密斯,如果我没有误会)容易找到的香草 RelayCommand
。
When I set the property in the ViewModel constructor, the correct value is properly displayed in View, but when I set this property with the command's method, the View doesn't update, although any breakpoint I create is reached (even inside RaisePropertyChanged
in my ViewModelBase
). I am using vanilla RelayCommand
found easily in online tutorials (from Josh Smith if I am not mistaken).
我的项目可以下载 here (Dropbox);
My project can be downloaded here (Dropbox);
一些重要的代码块如下:
Some important code blocks are below:
ViewModel:
ViewModel:
public class IdiomaViewModel : ViewModelBase
{
public String Idioma {
get { return _idioma; }
set {
_idioma = value;
RaisePropertyChanged(() => Idioma);
}
}
String _idioma;
public IdiomaViewModel() {
Idioma = "nenhum";
}
public void Portugues () {
Idioma = "portu";
}
private bool PodePortugues()
{
if (true) // <-- incluir teste aqui!!!
return true;
return false;
}
RelayCommand _comando_portugues;
public ICommand ComandoPortugues {
get {
if (_comando_portugues == null) {
_comando_portugues = new RelayCommand(param => Portugues(),
param => PodePortugues());
}
return _comando_portugues;
}
}
public void Ingles () {
Idioma = "ingle";
}
private bool PodeIngles()
{
if (true) // <-- incluir teste aqui!!!
return true;
return false;
}
RelayCommand _comando_ingles;
public ICommand ComandoIngles {
get {
if (_comando_ingles == null) {
_comando_ingles = new RelayCommand(param => Ingles(),
param => PodeIngles());
}
return _comando_ingles;
}
}
}
没有额外的代码:
<Window x:Class="TemQueFuncionar.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:app="clr-namespace:TemQueFuncionar"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<app:IdiomaViewModel/>
</Window.DataContext>
<StackPanel>
<Button Content="Ingles" Command="{Binding ComandoIngles, Mode=OneWay}"/>
<Button Content="Portugues" Command="{Binding ComandoPortugues, Mode=OneWay}"/>
<Label Content="{Binding Idioma}"/>
</StackPanel>
</Window>
推荐答案
Youdid填写接口实现,你没有提到到基本视图模型。
你错过了这个:INotifyPropertyChanged
链接到基类的接口,这使得View刷新内容。
Youdid fill the Interface implementation put you did not mention it to the base view model.
You are missing this : INotifyPropertyChanged
linking Interface to the base class, this makes the the View refreshes the content.
这篇关于在命令中设置属性时,绑定不会更新的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!